[IRBuilder] Virtualize IRBuilder

[nikic]

Summary

This patch moves the IRBuilder from templating over the constant folder and inserter towards making both of these virtual. There are a couple of motivations for this:

• Currently, it's hard/impossible to share code using IRBuilders with different folders/inserters. The original motivation was to make the SimplifyLibCalls utility (which further depends on the BuildLibCall utility) make use of the InstCombine IR builder (which uses a custom inserter). However, there isn't really any way to do that without bleeding the used inserter across the codebase.
• There are some creation methods on BaseBuilder. However, these do not make use of the inserter and perform manual insertion instead, making the inserter callback unreliable. This happened because the BaseBuilder just doesn't have access to the inserter...
• Nearly the entirety of IRBuilder is implemented as inline methods in the header. This is a hefty 3k loc file and very little of it looks like code that benefits from being inlined. However, because it depends on the template arguments, it cannot be moved into the source file.

This patch addresses the issue by making the following changes:

• IRBuilderDefaultInserter::InsertHelper becomes virtual. The IRBuilderBase accepts a reference to it.
• IRBuilderFolder is introduced as a virtual base class. It is implemented by ConstantFolder (default), NoFolder and TargetFolder. The IRBuilderBase has a reference to this as well.
• All the logic is moved from IRBuilder to IRBuilderBase. This means that methods can in the future replace their IRBuilder<> & uses (or other specific IRBuilder types) with IRBuilderBase & and thus be usable with different IRBuilders.
• The IRBuilder class is now a thin wrapper around IRBuilderBase. Essentially it only stores the folder and inserter and takes care of constructing the base builder.

What this patch doesn't do, but should be simple followups after this change:

• Fixing use of the inserter for creation methods originally defined on IRBuilderBase (this is a trivial change, keeping it out of here to keep things NFC).
• Replacing IRBuilder<> uses in arguments with IRBuilderBase, where useful.
• Moving code from the IRBuilder header to the source file.

From the user perspective, these changes are mostly transparent: The only thing that consumers may need to do is mark their InsertHelper as public instead of protected. (This patch currently only has the LLVM part, one or two adjustments like that will be needed in clang/polly).

What do you think?

[Meinersbur]

In my experience, LLVM tends more towards removing virtual inheritance and towards compile-time polymorphism (e.g. the pass manager, llvm::Instruction without vtable). This is a patch into the other direction. Personally, I prefer to use the language-provided mechanism.

There might be a performance impact (less inlining), it would help if you could measure it.

[nikic]

Rebase over committed changes and add vtable anchors.

[nikic]

In D73835#1857028, @Meinersbur wrote:

In my experience, LLVM tends more towards removing virtual inheritance and towards compile-time polymorphism (e.g. the pass manager, llvm::Instruction without vtable). This is a patch into the other direction. Personally, I prefer to use the language-provided mechanism.

There might be a performance impact (less inlining), it would help if you could measure it.

Unfortunately I don't have a setup suitable to perform compile-time benchmarks. I can barely get LLVM built, my previous attempts at compile-time measurements were hopelessly noisy. I can't really imagine IRBuilder taking up a large fraction of compile-time though (I don't believe I've ever seen it show up in profiles.)

I'm not particularly good with C++, so if there's some other way to go about this that avoids using "virtual", I'd be happy to try that. I think that disregarding all the other considerations, the one issue here that must be fixed one way or another is that the "inserter" is not used if methods defined on IRBuilderBase are called. In particular this means that any intrinsics inserted by InstCombine right now do not get added to the worklist. Other passes that use a custom inserter probably experience similar subtle issues.

It might make sense to break this patch up to address just add that issue first, and leave the more involved "constant folder" changes to another patch. That would still require making something virtual though... either by making the inserter virtual (what this patch does), or making IRBuilder::Insert virtual (https://gist.github.com/nikic/7d6223bc0df4798181fa781ca771e78c for a quick prototype). I actually like the latter a bit more (it is less intrusive), but this approach doesn't allow us to perform vtable anchoring (I don't know how much we care about that). Another possibility would be to just add an std::function callback on IRBuilderBase -- which is essentially the same as using "virtual", but leaves us in control of the implementation details.

[Meinersbur]

In D73835#1857727, @nikic wrote:

In D73835#1857028, @Meinersbur wrote:

In my experience, LLVM tends more towards removing virtual inheritance and towards compile-time polymorphism (e.g. the pass manager, llvm::Instruction without vtable). This is a patch into the other direction. Personally, I prefer to use the language-provided mechanism.

There might be a performance impact (less inlining), it would help if you could measure it.

Unfortunately I don't have a setup suitable to perform compile-time benchmarks. I can barely get LLVM built, my previous attempts at compile-time measurements were hopelessly noisy. I can't really imagine IRBuilder taking up a large fraction of compile-time though (I don't believe I've ever seen it show up in profiles.)

It doesn't need to be an entire run of clang. Even a result 'difference is not significant' behind the noise is some supporting result over guessing.

I'm not particularly good with C++, so if there's some other way to go about this that avoids using "virtual", I'd be happy to try that. I think that disregarding all the other considerations, the one issue here that must be fixed one way or another is that the "inserter" is not used if methods defined on IRBuilderBase are called. In particular this means that any intrinsics inserted by InstCombine right now do not get added to the worklist. Other passes that use a custom inserter probably experience similar subtle issues.

The obvious solution would be to move these methods from IRBuilderBase to IRBuilder.

This is a significant change for the framework, I'd recommend writing an RFC to the llvm-dev list to get more feedback.

[nhaehnle]

If people are concerned about virtual function calls, I do think it may be possible to have a generic builder class using virtual dispatch, but also a variant that doesn't use virtual dispatch. I've outlined a possible direction here: https://pastebin.com/i4mC6GAf

That said, I think it's plausible that just using virtual dispatch unconditionally is fine, some superficial compile-time benchmarks would be nice.

[Meinersbur]

In D73835#1861418, @nhaehnle wrote:

If people are concerned about virtual function calls,

To clarify: I am not, just pointing out that others might.

[nikic]

Add clang part (change protected -> public).

[nikic]

As a sanity check for compile-time I've compared build times for zend_execute.c (about 60k lines of C code before expansion). Raw perf stat results at https://gist.github.com/nikic/9a87083358d98f34e8e64851a84ff864, here retired instruction counts for three runs each (timing results are too noisy on my machine):

        | before         | after
-O2 -g  | 68.602.837.460 | 68.821.051.076
        | 68.566.922.163 | 68.538.048.917
        | 68.538.997.311 | 68.509.463.180
-O0 -g  | 25.162.639.627 | 25.135.102.049
        | 25.129.536.208 | 25.093.005.413
        | 25.146.124.560 | 25.119.503.250
-O0 -g0 | 16.232.387.222 | 16.215.831.899
        | 16.200.846.485 | 16.231.492.196
        | 16.216.916.110 | 16.192.568.580

It looks like the difference is in the noise, at least for this test case.

[fhahn]

In D73835#1865599, @nikic wrote:

As a sanity check for compile-time I've compared build times for zend_execute.c (about 60k lines of C code before expansion). Raw perf stat results at https://gist.github.com/nikic/9a87083358d98f34e8e64851a84ff864, here retired instruction counts for three runs each (timing results are too noisy on my machine):

        | before         | after
-O2 -g  | 68.602.837.460 | 68.821.051.076
        | 68.566.922.163 | 68.538.048.917
        | 68.538.997.311 | 68.509.463.180
-O0 -g  | 25.162.639.627 | 25.135.102.049
        | 25.129.536.208 | 25.093.005.413
        | 25.146.124.560 | 25.119.503.250
-O0 -g0 | 16.232.387.222 | 16.215.831.899
        | 16.200.846.485 | 16.231.492.196
        | 16.216.916.110 | 16.192.568.580

It looks like the difference is in the noise, at least for this test case.

It might be also interesting to gather numbers for the CTMark part of the test-suite.

[theraven]

Please can we have some perf comparisons for just -emit-llvm (not invoking any of the back-end infrastructure)? Given the numbers so far, I'd expect these to also be in the noise, but even at -O0 a quite significant proportion of the compile time is spent after the stages that use IRBuilder.

[Meinersbur]

You can completely isolate the code generation time using the "Code Generation Time" timer from clang -ftime-report.

[nikic]

Rebase.

[nikic]

For the same test case as before, instruction counts with -emit-llvm -Xclang -disable-llvm-passes:

# before
8.409.134.507
8.439.851.250
8.436.145.165
# after
8.415.563.795
8.426.474.507
8.434.608.865

So this still looks like noise to me. And looking at a perf trace, IRBuilder methods show up with fractions of 0,01-0,04%, even with all optimizations and codegen disabled, so it's not very surprising that there is no observable difference.

[nhaehnle]

Two minor questions, apart from that LGTM.

llvm/include/llvm/Analysis/TargetFolder.h

32

Could we make the TargetFolder final?

llvm/include/llvm/IR/ConstantFolder.h

28

Same question here: could we make the ConstantFolder final?

[nikic]

Make ConstantFolder/TargetFolder/NoFolder final.

[nikic]

llvm/include/llvm/Analysis/TargetFolder.h

32

Yeah, don't see a reason not to... can always drop it again if someone is extending these for some reason.

[thakis]

This causes this build warning:

../../llvm/include/llvm/IR/IRBuilder.h:77:16: warning: 'anchor' overrides a member function but is not marked 'override' [-Winconsistent-missing-override]
  virtual void anchor();
               ^
../../llvm/include/llvm/IR/IRBuilder.h:62:16: note: overridden virtual function is here
  virtual void anchor();
               ^

[nikic]

Reverted because of failures on http://lab.llvm.org:8011/builders/llvm-clang-x86_64-expensive-checks-win/builds/22164. Not sure why this is the only builder that's failing, but I believe the problematic code is https://github.com/llvm/llvm-project/blob/af480e8c63b27ad247b8430cf124da8bcdf752f8/llvm/lib/IR/DIBuilder.cpp#L898-L910. Without NRVO this may copy IRBuilder<>, which is now self-referential due to the Folder/Inserter references in IRBuilderBase.

I'm not sure what the right way to fix this is. Should I add an explicit copy constructor? I guess that would also involve explicit move ctor and copy/move assignment, which seems pretty ugly. Maybe it makes more sense to explicitly delete it and just avoid the copy constructor in that particular code?

[nikic]

Tried what happens if the copy constructor is deleted: https://gist.github.com/nikic/1e6ab5bbf42cfe48e7b848e60a2df180 It looks like the referenced occurrence in DIBuilder was the only place that was using the copy constructor "for good reason", most of the other uses either copy the whole IRBuilder where they just want to pass a reference or copy the whole IRBuilder where they really just want an InsertPointGuard.

[xbolva00]

@nikic: Can you please do compile-time benchmarks w/o this patch with e.g. php ?

[teemperor]

This broke the LLVM_ENABLE_MODULES build because it introduces a cyclic dependency between LLVM_IR and LLVM_intrinsic_gen:

FAILED: tools/lld/lib/ReaderWriter/MachO/CMakeFiles/lldMachO.dir/MachONormalizedFileBinaryReader.cpp.o 
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/c++  -DGTEST_HAS_RTTI=0 -D_DEBUG -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -Itools/lld/lib/ReaderWriter/MachO -I/Users/teemperor/1llvm/llvm-project/lld/lib/ReaderWriter/MachO -I/Users/teemperor/1llvm/llvm-project/lld/include -Itools/lld/include -I/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.15.sdk/usr/include/libxml2 -Iinclude -I/Users/teemperor/1llvm/llvm-project/llvm/include -I/Users/teemperor/1llvm/llvm-project/lld/lib/ReaderWriter/MachO/. -fPIC -fvisibility-inlines-hidden -Werror=date-time -Werror=unguarded-availability-new -fmodules -fmodules-cache-path=/Users/teemperor/1llvm/rel/module.cache -fcxx-modules -Wall -Wextra -Wno-unused-parameter -Wwrite-strings -Wcast-qual -Wmissing-field-initializers -pedantic -Wno-long-long -Wimplicit-fallthrough -Wcovered-switch-default -Wno-noexcept-type -Wnon-virtual-dtor -Wdelete-non-virtual-dtor -Wstring-conversion -fdiagnostics-color -O3  -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.15.sdk    -fno-exceptions -fno-rtti -UNDEBUG -std=c++14 -MD -MT tools/lld/lib/ReaderWriter/MachO/CMakeFiles/lldMachO.dir/MachONormalizedFileBinaryReader.cpp.o -MF tools/lld/lib/ReaderWriter/MachO/CMakeFiles/lldMachO.dir/MachONormalizedFileBinaryReader.cpp.o.d -o tools/lld/lib/ReaderWriter/MachO/CMakeFiles/lldMachO.dir/MachONormalizedFileBinaryReader.cpp.o -c /Users/teemperor/1llvm/llvm-project/lld/lib/ReaderWriter/MachO/MachONormalizedFileBinaryReader.cpp
While building module 'LLVM_Object' imported from /Users/teemperor/1llvm/llvm-project/lld/lib/ReaderWriter/MachO/MachONormalizedFileBinaryReader.cpp:36:
While building module 'LLVM_IR' imported from /Users/teemperor/1llvm/llvm-project/llvm/include/llvm/Object/IRSymtab.h:29:
While building module 'LLVM_intrinsic_gen' imported from /Users/teemperor/1llvm/llvm-project/llvm/include/llvm/IR/IRBuilderFolder.h:18:
In file included from <module-includes>:1:
/Users/teemperor/1llvm/llvm-project/llvm/include/llvm/IR/Argument.h:19:10: fatal error: cyclic dependency in module 'LLVM_IR': LLVM_IR -> LLVM_intrinsic_gen -> LLVM_IR
#include "llvm/IR/Value.h"
         ^
While building module 'LLVM_Object' imported from /Users/teemperor/1llvm/llvm-project/lld/lib/ReaderWriter/MachO/MachONormalizedFileBinaryReader.cpp:36:
While building module 'LLVM_IR' imported from /Users/teemperor/1llvm/llvm-project/llvm/include/llvm/Object/IRSymtab.h:29:
In file included from <module-includes>:13:
/Users/teemperor/1llvm/llvm-project/llvm/include/llvm/IR/IRBuilderFolder.h:18:10: fatal error: could not build module 'LLVM_intrinsic_gen'
#include "llvm/IR/InstrTypes.h"
 ~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~
While building module 'LLVM_Object' imported from /Users/teemperor/1llvm/llvm-project/lld/lib/ReaderWriter/MachO/MachONormalizedFileBinaryReader.cpp:36:
In file included from <module-includes>:4:
/Users/teemperor/1llvm/llvm-project/llvm/include/llvm/Object/IRSymtab.h:29:10: fatal error: could not build module 'LLVM_IR'
#include "llvm/IR/GlobalValue.h"
 ~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~
/Users/teemperor/1llvm/llvm-project/lld/lib/ReaderWriter/MachO/MachONormalizedFileBinaryReader.cpp:36:10: fatal error: could not build module 'LLVM_Object'
#include "llvm/Object/MachO.h"
 ~~~~~~~~^~~~~~~~~~~~~~~~~~~~~
4 errors generated.

[modocache]

llvm/include/llvm/IR/IRBuilder.h

136

I experienced a tiny regression after applying this patch, and I think this line might be the reason why. I tried addressing the issue in D74754, please give that a review when you get a chance.

clang/lib/CodeGen/CGBuilder.h

 namespace clang {
 namespace CodeGen {
 
 class CodeGenFunction;
 
 /// This is an IRBuilder insertion helper that forwards to
 /// CodeGenFunction::InsertHelper, which adds necessary metadata to
 /// instructions.
-class CGBuilderInserter : protected llvm::IRBuilderDefaultInserter {
+class CGBuilderInserter : public llvm::IRBuilderDefaultInserter {
 public:
   CGBuilderInserter() = default;
   explicit CGBuilderInserter(CodeGenFunction *CGF) : CGF(CGF) {}
 
-protected:
   /// This forwards to CodeGenFunction::InsertHelper.
   void InsertHelper(llvm::Instruction *I, const llvm::Twine &Name,
                     llvm::BasicBlock *BB,
-                    llvm::BasicBlock::iterator InsertPt) const;
+                    llvm::BasicBlock::iterator InsertPt) const override;
 private:
   CodeGenFunction *CGF = nullptr;
 };
 
 typedef CGBuilderInserter CGBuilderInserterTy;
 
 typedef llvm::IRBuilder<llvm::ConstantFolder, CGBuilderInserterTy>
     CGBuilderBaseTy;

llvm/include/llvm/Analysis/TargetFolder.h

 
 #ifndef LLVM_ANALYSIS_TARGETFOLDER_H
 #define LLVM_ANALYSIS_TARGETFOLDER_H
 
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/Analysis/ConstantFolding.h"
 #include "llvm/IR/Constants.h"
 #include "llvm/IR/InstrTypes.h"
+#include "llvm/IR/IRBuilderFolder.h"
 
 namespace llvm {
 
 class DataLayout;
 
 /// TargetFolder - Create constants with target dependent folding.
-class TargetFolder {
+class TargetFolder : public IRBuilderFolder {
   const DataLayout &DL;
 
   /// Fold - Fold the constant using target specific information.
   Constant *Fold(Constant *C) const {
     if (Constant *CF = ConstantFoldConstant(C, DL))
       return CF;
     return C;
   }
 
+  virtual void anchor();
+
 public:
   explicit TargetFolder(const DataLayout &DL) : DL(DL) {}
 
   //===--------------------------------------------------------------------===//
   // Binary Operators
   //===--------------------------------------------------------------------===//
 
   Constant *CreateAdd(Constant *LHS, Constant *RHS,
-                      bool HasNUW = false, bool HasNSW = false) const {
+                      bool HasNUW = false, bool HasNSW = false) const override {
     return Fold(ConstantExpr::getAdd(LHS, RHS, HasNUW, HasNSW));
   }
-  Constant *CreateFAdd(Constant *LHS, Constant *RHS) const {
+  Constant *CreateFAdd(Constant *LHS, Constant *RHS) const override {
     return Fold(ConstantExpr::getFAdd(LHS, RHS));
   }
   Constant *CreateSub(Constant *LHS, Constant *RHS,
-                      bool HasNUW = false, bool HasNSW = false) const {
+                      bool HasNUW = false, bool HasNSW = false) const override {
     return Fold(ConstantExpr::getSub(LHS, RHS, HasNUW, HasNSW));
   }
-  Constant *CreateFSub(Constant *LHS, Constant *RHS) const {
+  Constant *CreateFSub(Constant *LHS, Constant *RHS) const override {
     return Fold(ConstantExpr::getFSub(LHS, RHS));
   }
   Constant *CreateMul(Constant *LHS, Constant *RHS,
-                      bool HasNUW = false, bool HasNSW = false) const {
+                      bool HasNUW = false, bool HasNSW = false) const override {
     return Fold(ConstantExpr::getMul(LHS, RHS, HasNUW, HasNSW));
   }
-  Constant *CreateFMul(Constant *LHS, Constant *RHS) const {
+  Constant *CreateFMul(Constant *LHS, Constant *RHS) const override {
     return Fold(ConstantExpr::getFMul(LHS, RHS));
   }
-  Constant *CreateUDiv(Constant *LHS, Constant *RHS, bool isExact = false)const{
+  Constant *CreateUDiv(Constant *LHS, Constant *RHS,
+                       bool isExact = false) const override {
     return Fold(ConstantExpr::getUDiv(LHS, RHS, isExact));
   }
-  Constant *CreateSDiv(Constant *LHS, Constant *RHS, bool isExact = false)const{
+  Constant *CreateSDiv(Constant *LHS, Constant *RHS,
+                       bool isExact = false) const override {
     return Fold(ConstantExpr::getSDiv(LHS, RHS, isExact));
   }
-  Constant *CreateFDiv(Constant *LHS, Constant *RHS) const {
+  Constant *CreateFDiv(Constant *LHS, Constant *RHS) const override {
     return Fold(ConstantExpr::getFDiv(LHS, RHS));
   }
-  Constant *CreateURem(Constant *LHS, Constant *RHS) const {
+  Constant *CreateURem(Constant *LHS, Constant *RHS) const override {
     return Fold(ConstantExpr::getURem(LHS, RHS));
   }
-  Constant *CreateSRem(Constant *LHS, Constant *RHS) const {
+  Constant *CreateSRem(Constant *LHS, Constant *RHS) const override {
     return Fold(ConstantExpr::getSRem(LHS, RHS));
   }
-  Constant *CreateFRem(Constant *LHS, Constant *RHS) const {
+  Constant *CreateFRem(Constant *LHS, Constant *RHS) const override {
     return Fold(ConstantExpr::getFRem(LHS, RHS));
   }
   Constant *CreateShl(Constant *LHS, Constant *RHS,
-                      bool HasNUW = false, bool HasNSW = false) const {
+                      bool HasNUW = false, bool HasNSW = false) const override {
     return Fold(ConstantExpr::getShl(LHS, RHS, HasNUW, HasNSW));
   }
-  Constant *CreateLShr(Constant *LHS, Constant *RHS, bool isExact = false)const{
+  Constant *CreateLShr(Constant *LHS, Constant *RHS,
+                       bool isExact = false) const override {
     return Fold(ConstantExpr::getLShr(LHS, RHS, isExact));
   }
-  Constant *CreateAShr(Constant *LHS, Constant *RHS, bool isExact = false)const{
+  Constant *CreateAShr(Constant *LHS, Constant *RHS,
+                       bool isExact = false) const override {
     return Fold(ConstantExpr::getAShr(LHS, RHS, isExact));
   }
-  Constant *CreateAnd(Constant *LHS, Constant *RHS) const {
+  Constant *CreateAnd(Constant *LHS, Constant *RHS) const override {
     return Fold(ConstantExpr::getAnd(LHS, RHS));
   }
-  Constant *CreateOr(Constant *LHS, Constant *RHS) const {
+  Constant *CreateOr(Constant *LHS, Constant *RHS) const override {
     return Fold(ConstantExpr::getOr(LHS, RHS));
   }
-  Constant *CreateXor(Constant *LHS, Constant *RHS) const {
+  Constant *CreateXor(Constant *LHS, Constant *RHS) const override {
     return Fold(ConstantExpr::getXor(LHS, RHS));
   }
 
   Constant *CreateBinOp(Instruction::BinaryOps Opc,
-                        Constant *LHS, Constant *RHS) const {
+                        Constant *LHS, Constant *RHS) const override {
     return Fold(ConstantExpr::get(Opc, LHS, RHS));
   }
 
   //===--------------------------------------------------------------------===//
   // Unary Operators
   //===--------------------------------------------------------------------===//
 
   Constant *CreateNeg(Constant *C,
-                      bool HasNUW = false, bool HasNSW = false) const {
+                      bool HasNUW = false, bool HasNSW = false) const override {
     return Fold(ConstantExpr::getNeg(C, HasNUW, HasNSW));
   }
-  Constant *CreateFNeg(Constant *C) const {
+  Constant *CreateFNeg(Constant *C) const override {
     return Fold(ConstantExpr::getFNeg(C));
   }
-  Constant *CreateNot(Constant *C) const {
+  Constant *CreateNot(Constant *C) const override {
     return Fold(ConstantExpr::getNot(C));
   }
 
-  Constant *CreateUnOp(Instruction::UnaryOps Opc, Constant *C) const {
+  Constant *CreateUnOp(Instruction::UnaryOps Opc, Constant *C) const override {
     return Fold(ConstantExpr::get(Opc, C));
   }
 
   //===--------------------------------------------------------------------===//
   // Memory Instructions
   //===--------------------------------------------------------------------===//
 
   Constant *CreateGetElementPtr(Type *Ty, Constant *C,
-                                ArrayRef<Constant *> IdxList) const {
+                                ArrayRef<Constant *> IdxList) const override {
     return Fold(ConstantExpr::getGetElementPtr(Ty, C, IdxList));
   }
-  Constant *CreateGetElementPtr(Type *Ty, Constant *C, Constant *Idx) const {
+  Constant *CreateGetElementPtr(Type *Ty, Constant *C,
+                                Constant *Idx) const override {
     // This form of the function only exists to avoid ambiguous overload
     // warnings about whether to convert Idx to ArrayRef<Constant *> or
     // ArrayRef<Value *>.
     return Fold(ConstantExpr::getGetElementPtr(Ty, C, Idx));
   }
   Constant *CreateGetElementPtr(Type *Ty, Constant *C,
-                                ArrayRef<Value *> IdxList) const {
+                                ArrayRef<Value *> IdxList) const override {
     return Fold(ConstantExpr::getGetElementPtr(Ty, C, IdxList));
   }
 
-  Constant *CreateInBoundsGetElementPtr(Type *Ty, Constant *C,
-                                        ArrayRef<Constant *> IdxList) const {
+  Constant *CreateInBoundsGetElementPtr(
+      Type *Ty, Constant *C, ArrayRef<Constant *> IdxList) const override {
     return Fold(ConstantExpr::getInBoundsGetElementPtr(Ty, C, IdxList));
   }
   Constant *CreateInBoundsGetElementPtr(Type *Ty, Constant *C,
-                                        Constant *Idx) const {
+                                        Constant *Idx) const override {
     // This form of the function only exists to avoid ambiguous overload
     // warnings about whether to convert Idx to ArrayRef<Constant *> or
     // ArrayRef<Value *>.
     return Fold(ConstantExpr::getInBoundsGetElementPtr(Ty, C, Idx));
   }
-  Constant *CreateInBoundsGetElementPtr(Type *Ty, Constant *C,
-                                        ArrayRef<Value *> IdxList) const {
+  Constant *CreateInBoundsGetElementPtr(
+      Type *Ty, Constant *C, ArrayRef<Value *> IdxList) const override {
     return Fold(ConstantExpr::getInBoundsGetElementPtr(Ty, C, IdxList));
   }
 
   //===--------------------------------------------------------------------===//
   // Cast/Conversion Operators
   //===--------------------------------------------------------------------===//
 
   Constant *CreateCast(Instruction::CastOps Op, Constant *C,
-                       Type *DestTy) const {
+                       Type *DestTy) const override {
     if (C->getType() == DestTy)
       return C; // avoid calling Fold
     return Fold(ConstantExpr::getCast(Op, C, DestTy));
   }
   Constant *CreateIntCast(Constant *C, Type *DestTy,
-                          bool isSigned) const {
+                          bool isSigned) const override {
     if (C->getType() == DestTy)
       return C; // avoid calling Fold
     return Fold(ConstantExpr::getIntegerCast(C, DestTy, isSigned));
   }
-  Constant *CreatePointerCast(Constant *C, Type *DestTy) const {
+  Constant *CreatePointerCast(Constant *C, Type *DestTy) const override {
     if (C->getType() == DestTy)
       return C; // avoid calling Fold
     return Fold(ConstantExpr::getPointerCast(C, DestTy));
   }
-  Constant *CreateFPCast(Constant *C, Type *DestTy) const {
+  Constant *CreateFPCast(Constant *C, Type *DestTy) const override {
     if (C->getType() == DestTy)
       return C; // avoid calling Fold
     return Fold(ConstantExpr::getFPCast(C, DestTy));
   }
-  Constant *CreateBitCast(Constant *C, Type *DestTy) const {
+  Constant *CreateBitCast(Constant *C, Type *DestTy) const override {
     return CreateCast(Instruction::BitCast, C, DestTy);
   }
-  Constant *CreateIntToPtr(Constant *C, Type *DestTy) const {
+  Constant *CreateIntToPtr(Constant *C, Type *DestTy) const override {
     return CreateCast(Instruction::IntToPtr, C, DestTy);
   }
-  Constant *CreatePtrToInt(Constant *C, Type *DestTy) const {
+  Constant *CreatePtrToInt(Constant *C, Type *DestTy) const override {
     return CreateCast(Instruction::PtrToInt, C, DestTy);
   }
-  Constant *CreateZExtOrBitCast(Constant *C, Type *DestTy) const {
+  Constant *CreateZExtOrBitCast(Constant *C, Type *DestTy) const override {
     if (C->getType() == DestTy)
       return C; // avoid calling Fold
     return Fold(ConstantExpr::getZExtOrBitCast(C, DestTy));
   }
-  Constant *CreateSExtOrBitCast(Constant *C, Type *DestTy) const {
+  Constant *CreateSExtOrBitCast(Constant *C, Type *DestTy) const override {
     if (C->getType() == DestTy)
       return C; // avoid calling Fold
     return Fold(ConstantExpr::getSExtOrBitCast(C, DestTy));
   }
-  Constant *CreateTruncOrBitCast(Constant *C, Type *DestTy) const {
+  Constant *CreateTruncOrBitCast(Constant *C, Type *DestTy) const override {
     if (C->getType() == DestTy)
       return C; // avoid calling Fold
     return Fold(ConstantExpr::getTruncOrBitCast(C, DestTy));
   }
 
   Constant *CreatePointerBitCastOrAddrSpaceCast(Constant *C,
-                                                Type *DestTy) const {
+                                                Type *DestTy) const override {
     if (C->getType() == DestTy)
       return C; // avoid calling Fold
     return Fold(ConstantExpr::getPointerBitCastOrAddrSpaceCast(C, DestTy));
   }
 
   //===--------------------------------------------------------------------===//
   // Compare Instructions
   //===--------------------------------------------------------------------===//
 
   Constant *CreateICmp(CmpInst::Predicate P, Constant *LHS,
-                       Constant *RHS) const {
+                       Constant *RHS) const override {
     return Fold(ConstantExpr::getCompare(P, LHS, RHS));
   }
   Constant *CreateFCmp(CmpInst::Predicate P, Constant *LHS,
-                       Constant *RHS) const {
+                       Constant *RHS) const override {
     return Fold(ConstantExpr::getCompare(P, LHS, RHS));
   }
 
   //===--------------------------------------------------------------------===//
   // Other Instructions
   //===--------------------------------------------------------------------===//
 
-  Constant *CreateSelect(Constant *C, Constant *True, Constant *False) const {
+  Constant *CreateSelect(Constant *C, Constant *True,
+                         Constant *False) const override {
     return Fold(ConstantExpr::getSelect(C, True, False));
   }
 
-  Constant *CreateExtractElement(Constant *Vec, Constant *Idx) const {
+  Constant *CreateExtractElement(Constant *Vec, Constant *Idx) const override {
     return Fold(ConstantExpr::getExtractElement(Vec, Idx));
   }
 
   Constant *CreateInsertElement(Constant *Vec, Constant *NewElt,
-                                Constant *Idx) const {
+                                Constant *Idx) const override {
     return Fold(ConstantExpr::getInsertElement(Vec, NewElt, Idx));
   }
 
   Constant *CreateShuffleVector(Constant *V1, Constant *V2,
-                                Constant *Mask) const {
+                                Constant *Mask) const override {
     return Fold(ConstantExpr::getShuffleVector(V1, V2, Mask));
   }
 
   Constant *CreateExtractValue(Constant *Agg,
-                               ArrayRef<unsigned> IdxList) const {
+                               ArrayRef<unsigned> IdxList) const override {
     return Fold(ConstantExpr::getExtractValue(Agg, IdxList));
   }
 
   Constant *CreateInsertValue(Constant *Agg, Constant *Val,
-                              ArrayRef<unsigned> IdxList) const {
+                              ArrayRef<unsigned> IdxList) const override {
     return Fold(ConstantExpr::getInsertValue(Agg, Val, IdxList));
   }
 };
 
 }
 
 #endif

llvm/include/llvm/IR/ConstantFolder.h

 
 #ifndef LLVM_IR_CONSTANTFOLDER_H
 #define LLVM_IR_CONSTANTFOLDER_H
 
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/IR/Constants.h"
 #include "llvm/IR/InstrTypes.h"
 #include "llvm/IR/Instruction.h"
+#include "llvm/IR/IRBuilderFolder.h"
 
 namespace llvm {
 
 /// ConstantFolder - Create constants with minimum, target independent, folding.
-class ConstantFolder {
+class ConstantFolder : public IRBuilderFolder {
+  virtual void anchor();
+
 public:
   explicit ConstantFolder() = default;
 
   //===--------------------------------------------------------------------===//
   // Binary Operators
   //===--------------------------------------------------------------------===//
 
   Constant *CreateAdd(Constant *LHS, Constant *RHS,
-                      bool HasNUW = false, bool HasNSW = false) const {
+                      bool HasNUW = false, bool HasNSW = false) const override {
     return ConstantExpr::getAdd(LHS, RHS, HasNUW, HasNSW);
   }
 
-  Constant *CreateFAdd(Constant *LHS, Constant *RHS) const {
+  Constant *CreateFAdd(Constant *LHS, Constant *RHS) const override {
     return ConstantExpr::getFAdd(LHS, RHS);
   }
 
   Constant *CreateSub(Constant *LHS, Constant *RHS,
-                      bool HasNUW = false, bool HasNSW = false) const {
+                      bool HasNUW = false, bool HasNSW = false) const override {
     return ConstantExpr::getSub(LHS, RHS, HasNUW, HasNSW);
   }
 
-  Constant *CreateFSub(Constant *LHS, Constant *RHS) const {
+  Constant *CreateFSub(Constant *LHS, Constant *RHS) const override {
     return ConstantExpr::getFSub(LHS, RHS);
   }
 
   Constant *CreateMul(Constant *LHS, Constant *RHS,
-                      bool HasNUW = false, bool HasNSW = false) const {
+                      bool HasNUW = false, bool HasNSW = false) const override {
     return ConstantExpr::getMul(LHS, RHS, HasNUW, HasNSW);
   }
 
-  Constant *CreateFMul(Constant *LHS, Constant *RHS) const {
+  Constant *CreateFMul(Constant *LHS, Constant *RHS) const override {
     return ConstantExpr::getFMul(LHS, RHS);
   }
 
   Constant *CreateUDiv(Constant *LHS, Constant *RHS,
-                       bool isExact = false) const {
+                               bool isExact = false) const override {
     return ConstantExpr::getUDiv(LHS, RHS, isExact);
   }
 
   Constant *CreateSDiv(Constant *LHS, Constant *RHS,
-                       bool isExact = false) const {
+                               bool isExact = false) const override {
     return ConstantExpr::getSDiv(LHS, RHS, isExact);
   }
 
-  Constant *CreateFDiv(Constant *LHS, Constant *RHS) const {
+  Constant *CreateFDiv(Constant *LHS, Constant *RHS) const override {
     return ConstantExpr::getFDiv(LHS, RHS);
   }
 
-  Constant *CreateURem(Constant *LHS, Constant *RHS) const {
+  Constant *CreateURem(Constant *LHS, Constant *RHS) const override {
     return ConstantExpr::getURem(LHS, RHS);
   }
 
-  Constant *CreateSRem(Constant *LHS, Constant *RHS) const {
+  Constant *CreateSRem(Constant *LHS, Constant *RHS) const override {
     return ConstantExpr::getSRem(LHS, RHS);
   }
 
-  Constant *CreateFRem(Constant *LHS, Constant *RHS) const {
+  Constant *CreateFRem(Constant *LHS, Constant *RHS) const override {
     return ConstantExpr::getFRem(LHS, RHS);
   }
 
   Constant *CreateShl(Constant *LHS, Constant *RHS,
-                      bool HasNUW = false, bool HasNSW = false) const {
+                      bool HasNUW = false, bool HasNSW = false) const override {
     return ConstantExpr::getShl(LHS, RHS, HasNUW, HasNSW);
   }
 
   Constant *CreateLShr(Constant *LHS, Constant *RHS,
-                       bool isExact = false) const {
+                       bool isExact = false) const override {
     return ConstantExpr::getLShr(LHS, RHS, isExact);
   }
 
   Constant *CreateAShr(Constant *LHS, Constant *RHS,
-                       bool isExact = false) const {
+                       bool isExact = false) const override {
     return ConstantExpr::getAShr(LHS, RHS, isExact);
   }
 
-  Constant *CreateAnd(Constant *LHS, Constant *RHS) const {
+  Constant *CreateAnd(Constant *LHS, Constant *RHS) const override {
     return ConstantExpr::getAnd(LHS, RHS);
   }
 
-  Constant *CreateOr(Constant *LHS, Constant *RHS) const {
+  Constant *CreateOr(Constant *LHS, Constant *RHS) const override {
     return ConstantExpr::getOr(LHS, RHS);
   }
 
-  Constant *CreateXor(Constant *LHS, Constant *RHS) const {
+  Constant *CreateXor(Constant *LHS, Constant *RHS) const override {
     return ConstantExpr::getXor(LHS, RHS);
   }
 
   Constant *CreateBinOp(Instruction::BinaryOps Opc,
-                        Constant *LHS, Constant *RHS) const {
+                        Constant *LHS, Constant *RHS) const override {
     return ConstantExpr::get(Opc, LHS, RHS);
   }
 
   //===--------------------------------------------------------------------===//
   // Unary Operators
   //===--------------------------------------------------------------------===//
 
   Constant *CreateNeg(Constant *C,
-                      bool HasNUW = false, bool HasNSW = false) const {
+                      bool HasNUW = false, bool HasNSW = false) const override {
     return ConstantExpr::getNeg(C, HasNUW, HasNSW);
   }
 
-  Constant *CreateFNeg(Constant *C) const {
+  Constant *CreateFNeg(Constant *C) const override {
     return ConstantExpr::getFNeg(C);
   }
 
-  Constant *CreateNot(Constant *C) const {
+  Constant *CreateNot(Constant *C) const override {
     return ConstantExpr::getNot(C);
   }
 
-  Constant *CreateUnOp(Instruction::UnaryOps Opc, Constant *C) const {
+  Constant *CreateUnOp(Instruction::UnaryOps Opc, Constant *C) const override {
     return ConstantExpr::get(Opc, C);
   }
 
   //===--------------------------------------------------------------------===//
   // Memory Instructions
   //===--------------------------------------------------------------------===//
 
   Constant *CreateGetElementPtr(Type *Ty, Constant *C,
-                                ArrayRef<Constant *> IdxList) const {
+                                ArrayRef<Constant *> IdxList) const override {
     return ConstantExpr::getGetElementPtr(Ty, C, IdxList);
   }
 
-  Constant *CreateGetElementPtr(Type *Ty, Constant *C, Constant *Idx) const {
+  Constant *CreateGetElementPtr(Type *Ty, Constant *C,
+                                Constant *Idx) const override {
     // This form of the function only exists to avoid ambiguous overload
     // warnings about whether to convert Idx to ArrayRef<Constant *> or
     // ArrayRef<Value *>.
     return ConstantExpr::getGetElementPtr(Ty, C, Idx);
   }
 
   Constant *CreateGetElementPtr(Type *Ty, Constant *C,
-                                ArrayRef<Value *> IdxList) const {
+                                ArrayRef<Value *> IdxList) const override {
     return ConstantExpr::getGetElementPtr(Ty, C, IdxList);
   }
 
-  Constant *CreateInBoundsGetElementPtr(Type *Ty, Constant *C,
-                                        ArrayRef<Constant *> IdxList) const {
+  Constant *CreateInBoundsGetElementPtr(
+      Type *Ty, Constant *C, ArrayRef<Constant *> IdxList) const override {
     return ConstantExpr::getInBoundsGetElementPtr(Ty, C, IdxList);
   }
 
   Constant *CreateInBoundsGetElementPtr(Type *Ty, Constant *C,
-                                        Constant *Idx) const {
+                                        Constant *Idx) const override {
     // This form of the function only exists to avoid ambiguous overload
     // warnings about whether to convert Idx to ArrayRef<Constant *> or
     // ArrayRef<Value *>.
     return ConstantExpr::getInBoundsGetElementPtr(Ty, C, Idx);
   }
 
-  Constant *CreateInBoundsGetElementPtr(Type *Ty, Constant *C,
-                                        ArrayRef<Value *> IdxList) const {
+  Constant *CreateInBoundsGetElementPtr(
+      Type *Ty, Constant *C, ArrayRef<Value *> IdxList) const override {
     return ConstantExpr::getInBoundsGetElementPtr(Ty, C, IdxList);
   }
 
   //===--------------------------------------------------------------------===//
   // Cast/Conversion Operators
   //===--------------------------------------------------------------------===//
 
   Constant *CreateCast(Instruction::CastOps Op, Constant *C,
-                       Type *DestTy) const {
+                       Type *DestTy) const override {
     return ConstantExpr::getCast(Op, C, DestTy);
   }
 
-  Constant *CreatePointerCast(Constant *C, Type *DestTy) const {
+  Constant *CreatePointerCast(Constant *C, Type *DestTy) const override {
     return ConstantExpr::getPointerCast(C, DestTy);
   }
 
   Constant *CreatePointerBitCastOrAddrSpaceCast(Constant *C,
-                                                Type *DestTy) const {
+                                                Type *DestTy) const override {
     return ConstantExpr::getPointerBitCastOrAddrSpaceCast(C, DestTy);
   }
 
   Constant *CreateIntCast(Constant *C, Type *DestTy,
-                          bool isSigned) const {
+                          bool isSigned) const override {
     return ConstantExpr::getIntegerCast(C, DestTy, isSigned);
   }
 
-  Constant *CreateFPCast(Constant *C, Type *DestTy) const {
+  Constant *CreateFPCast(Constant *C, Type *DestTy) const override {
     return ConstantExpr::getFPCast(C, DestTy);
   }
 
-  Constant *CreateBitCast(Constant *C, Type *DestTy) const {
+  Constant *CreateBitCast(Constant *C, Type *DestTy) const override {
     return CreateCast(Instruction::BitCast, C, DestTy);
   }
 
-  Constant *CreateIntToPtr(Constant *C, Type *DestTy) const {
+  Constant *CreateIntToPtr(Constant *C, Type *DestTy) const override {
     return CreateCast(Instruction::IntToPtr, C, DestTy);
   }
 
-  Constant *CreatePtrToInt(Constant *C, Type *DestTy) const {
+  Constant *CreatePtrToInt(Constant *C, Type *DestTy) const override {
     return CreateCast(Instruction::PtrToInt, C, DestTy);
   }
 
-  Constant *CreateZExtOrBitCast(Constant *C, Type *DestTy) const {
+  Constant *CreateZExtOrBitCast(Constant *C, Type *DestTy) const override {
     return ConstantExpr::getZExtOrBitCast(C, DestTy);
   }
 
-  Constant *CreateSExtOrBitCast(Constant *C, Type *DestTy) const {
+  Constant *CreateSExtOrBitCast(Constant *C, Type *DestTy) const override {
     return ConstantExpr::getSExtOrBitCast(C, DestTy);
   }
 
-  Constant *CreateTruncOrBitCast(Constant *C, Type *DestTy) const {
+  Constant *CreateTruncOrBitCast(Constant *C, Type *DestTy) const override {
     return ConstantExpr::getTruncOrBitCast(C, DestTy);
   }
 
   //===--------------------------------------------------------------------===//
   // Compare Instructions
   //===--------------------------------------------------------------------===//
 
   Constant *CreateICmp(CmpInst::Predicate P, Constant *LHS,
-                       Constant *RHS) const {
+                       Constant *RHS) const override {
     return ConstantExpr::getCompare(P, LHS, RHS);
   }
 
   Constant *CreateFCmp(CmpInst::Predicate P, Constant *LHS,
-                       Constant *RHS) const {
+                       Constant *RHS) const override {
     return ConstantExpr::getCompare(P, LHS, RHS);
   }
 
   //===--------------------------------------------------------------------===//
   // Other Instructions
   //===--------------------------------------------------------------------===//
 
-  Constant *CreateSelect(Constant *C, Constant *True, Constant *False) const {
+  Constant *CreateSelect(Constant *C, Constant *True,
+                         Constant *False) const override {
     return ConstantExpr::getSelect(C, True, False);
   }
 
-  Constant *CreateExtractElement(Constant *Vec, Constant *Idx) const {
+  Constant *CreateExtractElement(Constant *Vec, Constant *Idx) const override {
     return ConstantExpr::getExtractElement(Vec, Idx);
   }
 
   Constant *CreateInsertElement(Constant *Vec, Constant *NewElt,
-                                Constant *Idx) const {
+                                Constant *Idx) const override {
     return ConstantExpr::getInsertElement(Vec, NewElt, Idx);
   }
 
   Constant *CreateShuffleVector(Constant *V1, Constant *V2,
-                                Constant *Mask) const {
+                                Constant *Mask) const override {
     return ConstantExpr::getShuffleVector(V1, V2, Mask);
   }
 
   Constant *CreateExtractValue(Constant *Agg,
-                               ArrayRef<unsigned> IdxList) const {
+                               ArrayRef<unsigned> IdxList) const override {
     return ConstantExpr::getExtractValue(Agg, IdxList);
   }
 
   Constant *CreateInsertValue(Constant *Agg, Constant *Val,
-                              ArrayRef<unsigned> IdxList) const {
+                              ArrayRef<unsigned> IdxList) const override {
     return ConstantExpr::getInsertValue(Agg, Val, IdxList);
   }
 };
 
 } // end namespace llvm
 
 #endif // LLVM_IR_CONSTANTFOLDER_H

llvm/include/llvm/IR/IRBuilder.h

 class Use;
 
 /// This provides the default implementation of the IRBuilder
 /// 'InsertHelper' method that is called whenever an instruction is created by
 /// IRBuilder and needs to be inserted.
 ///
 /// By default, this inserts the instruction at the insertion point.
 class IRBuilderDefaultInserter {
-protected:
-  void InsertHelper(Instruction *I, const Twine &Name,
-                    BasicBlock *BB, BasicBlock::iterator InsertPt) const {
+  virtual void anchor();
+
+public:
+  virtual void InsertHelper(Instruction *I, const Twine &Name,
+                            BasicBlock *BB,
+                            BasicBlock::iterator InsertPt) const {
     if (BB) BB->getInstList().insert(InsertPt, I);
     I->setName(Name);
   }
 };
 
 /// Provides an 'InsertHelper' that calls a user-provided callback after
 /// performing the default insertion.
-class IRBuilderCallbackInserter : IRBuilderDefaultInserter {
+class IRBuilderCallbackInserter : public IRBuilderDefaultInserter {
   std::function<void(Instruction *)> Callback;
+  virtual void anchor();
 
 public:
   IRBuilderCallbackInserter(std::function<void(Instruction *)> Callback)
       : Callback(std::move(Callback)) {}
 
-protected:
   void InsertHelper(Instruction *I, const Twine &Name,
-                    BasicBlock *BB, BasicBlock::iterator InsertPt) const {
+                    BasicBlock *BB,
+                    BasicBlock::iterator InsertPt) const override {
     IRBuilderDefaultInserter::InsertHelper(I, Name, BB, InsertPt);
     Callback(I);
   }
 };
 
 /// Common base class shared among various IRBuilders.
 class IRBuilderBase {
   DebugLoc CurDbgLocation;
 
 protected:
   BasicBlock *BB;
   BasicBlock::iterator InsertPt;
   LLVMContext &Context;
+  const IRBuilderFolder &Folder;
+  const IRBuilderDefaultInserter &Inserter;
 
   MDNode *DefaultFPMathTag;
   FastMathFlags FMF;
 
   bool IsFPConstrained;
   fp::ExceptionBehavior DefaultConstrainedExcept;
   fp::RoundingMode DefaultConstrainedRounding;
 
   ArrayRef<OperandBundleDef> DefaultOperandBundles;
 
 public:
-  IRBuilderBase(LLVMContext &context, MDNode *FPMathTag = nullptr,
-                ArrayRef<OperandBundleDef> OpBundles = None)
-      : Context(context), DefaultFPMathTag(FPMathTag), IsFPConstrained(false),
+  IRBuilderBase(LLVMContext &context, const IRBuilderFolder &Folder,
+                const IRBuilderDefaultInserter &Inserter,
+                MDNode *FPMathTag, ArrayRef<OperandBundleDef> OpBundles)
+      : Context(context), Folder(Folder), Inserter(Inserter),
+        DefaultFPMathTag(FPMathTag), IsFPConstrained(false),
         DefaultConstrainedExcept(fp::ebStrict),
         DefaultConstrainedRounding(fp::rmDynamic),
         DefaultOperandBundles(OpBundles) {
     ClearInsertionPoint();
   }
 
+  /// Insert and return the specified instruction.
+  template<typename InstTy>
+  InstTy *Insert(InstTy *I, const Twine &Name = "") const {
+    Inserter.InsertHelper(I, Name, BB, InsertPt);
+    SetInstDebugLocation(I);
+    return I;
+  }
+
+  /// No-op overload to handle constants.
+  Constant *Insert(Constant *C, const Twine& = "") const {
+    return C;
+  }
+
+  Value *Insert(Value *V, const Twine& = "") const {
+    if (Instruction *I = dyn_cast<Instruction>(V))
+      return Insert(I);
+    assert(isa<Constant>(V));
+    return V;
+  }
+
   //===--------------------------------------------------------------------===//
   // Builder configuration methods
   //===--------------------------------------------------------------------===//
 
   /// Clear the insertion point: created instructions will not be
   /// inserted into a block.
   void ClearInsertionPoint() {
     BB = nullptr;

 
 private:
   /// Create a call to a masked intrinsic with given Id.
   CallInst *CreateMaskedIntrinsic(Intrinsic::ID Id, ArrayRef<Value *> Ops,
                                   ArrayRef<Type *> OverloadedTypes,
                                   const Twine &Name = "");
 
   Value *getCastedInt8PtrValue(Value *Ptr);
-};
-
-/// This provides a uniform API for creating instructions and inserting
-/// them into a basic block: either at the end of a BasicBlock, or at a specific
-/// iterator location in a block.
-///
-/// Note that the builder does not expose the full generality of LLVM
-/// instructions.  For access to extra instruction properties, use the mutators
-/// (e.g. setVolatile) on the instructions after they have been
-/// created. Convenience state exists to specify fast-math flags and fp-math
-/// tags.
-///
-/// The first template argument specifies a class to use for creating constants.
-/// This defaults to creating minimally folded constants.  The second template
-/// argument allows clients to specify custom insertion hooks that are called on
-/// every newly created insertion.
-template <typename T = ConstantFolder,
-          typename Inserter = IRBuilderDefaultInserter>
-class IRBuilder : public IRBuilderBase, public Inserter {
-  T Folder;
-
-public:
-  IRBuilder(LLVMContext &C, const T &F, Inserter I = Inserter(),
-            MDNode *FPMathTag = nullptr,
-            ArrayRef<OperandBundleDef> OpBundles = None)
-      : IRBuilderBase(C, FPMathTag, OpBundles), Inserter(std::move(I)),
-        Folder(F) {}
-
-  explicit IRBuilder(LLVMContext &C, MDNode *FPMathTag = nullptr,
-                     ArrayRef<OperandBundleDef> OpBundles = None)
-      : IRBuilderBase(C, FPMathTag, OpBundles) {}
-
-  explicit IRBuilder(BasicBlock *TheBB, const T &F, MDNode *FPMathTag = nullptr,
-                     ArrayRef<OperandBundleDef> OpBundles = None)
-      : IRBuilderBase(TheBB->getContext(), FPMathTag, OpBundles), Folder(F) {
-    SetInsertPoint(TheBB);
-  }
-
-  explicit IRBuilder(BasicBlock *TheBB, MDNode *FPMathTag = nullptr,
-                     ArrayRef<OperandBundleDef> OpBundles = None)
-      : IRBuilderBase(TheBB->getContext(), FPMathTag, OpBundles) {
-    SetInsertPoint(TheBB);
-  }
-
-  explicit IRBuilder(Instruction *IP, MDNode *FPMathTag = nullptr,
-                     ArrayRef<OperandBundleDef> OpBundles = None)
-      : IRBuilderBase(IP->getContext(), FPMathTag, OpBundles) {
-    SetInsertPoint(IP);
-  }
-
-  IRBuilder(BasicBlock *TheBB, BasicBlock::iterator IP, const T &F,
-            MDNode *FPMathTag = nullptr,
-            ArrayRef<OperandBundleDef> OpBundles = None)
-      : IRBuilderBase(TheBB->getContext(), FPMathTag, OpBundles), Folder(F) {
-    SetInsertPoint(TheBB, IP);
-  }
-
-  IRBuilder(BasicBlock *TheBB, BasicBlock::iterator IP,
-            MDNode *FPMathTag = nullptr,
-            ArrayRef<OperandBundleDef> OpBundles = None)
-      : IRBuilderBase(TheBB->getContext(), FPMathTag, OpBundles) {
-    SetInsertPoint(TheBB, IP);
-  }
 
-  /// Get the constant folder being used.
-  const T &getFolder() { return Folder; }
-
-  /// Insert and return the specified instruction.
-  template<typename InstTy>
-  InstTy *Insert(InstTy *I, const Twine &Name = "") const {
-    this->InsertHelper(I, Name, BB, InsertPt);
-    this->SetInstDebugLocation(I);
-    return I;
-  }
-
-  /// No-op overload to handle constants.
-  Constant *Insert(Constant *C, const Twine& = "") const {
-    return C;
-  }
 
   //===--------------------------------------------------------------------===//
   // Instruction creation methods: Terminators
   //===--------------------------------------------------------------------===//
 
 private:
   /// Helper to add branch weight and unpredictable metadata onto an
   /// instruction.
CallInst *CreateAlignmentAssumption(const DataLayout &DL, Value *PtrValue,
 
     Value *Mask = CreateSub(Alignment, ConstantInt::get(IntPtrTy, 1), "mask");
 
     return CreateAlignmentAssumptionHelper(DL, PtrValue, Mask, IntPtrTy,
                                            OffsetValue, TheCheck);
   }
 };
 
+/// This provides a uniform API for creating instructions and inserting
+/// them into a basic block: either at the end of a BasicBlock, or at a specific
+/// iterator location in a block.
+///
+/// Note that the builder does not expose the full generality of LLVM
+/// instructions.  For access to extra instruction properties, use the mutators
+/// (e.g. setVolatile) on the instructions after they have been
+/// created. Convenience state exists to specify fast-math flags and fp-math
+/// tags.
+///
+/// The first template argument specifies a class to use for creating constants.
+/// This defaults to creating minimally folded constants.  The second template
+/// argument allows clients to specify custom insertion hooks that are called on
+/// every newly created insertion.
+template <typename FolderTy = ConstantFolder,
+          typename InserterTy = IRBuilderDefaultInserter>
+class IRBuilder : public IRBuilderBase {
+private:
+  FolderTy Folder;
+  InserterTy Inserter;
+
+public:
+  IRBuilder(LLVMContext &C, FolderTy Folder, InserterTy Inserter = InserterTy(),
+            MDNode *FPMathTag = nullptr,
+            ArrayRef<OperandBundleDef> OpBundles = None)
+      : IRBuilderBase(C, this->Folder, this->Inserter, FPMathTag, OpBundles),
+        Folder(Folder), Inserter(Inserter) {}
+
+  explicit IRBuilder(LLVMContext &C, MDNode *FPMathTag = nullptr,
+                     ArrayRef<OperandBundleDef> OpBundles = None)
+      : IRBuilderBase(C, this->Folder, this->Inserter, FPMathTag, OpBundles) {}
+
+  explicit IRBuilder(BasicBlock *TheBB, FolderTy Folder,
+                     MDNode *FPMathTag = nullptr,
+                     ArrayRef<OperandBundleDef> OpBundles = None)
+      : IRBuilderBase(TheBB->getContext(), this->Folder, this->Inserter,
+                      FPMathTag, OpBundles), Folder(Folder) {
+    SetInsertPoint(TheBB);
+  }
+
+  explicit IRBuilder(BasicBlock *TheBB, MDNode *FPMathTag = nullptr,
+                     ArrayRef<OperandBundleDef> OpBundles = None)
+      : IRBuilderBase(TheBB->getContext(), this->Folder, this->Inserter,
+                      FPMathTag, OpBundles) {
+    SetInsertPoint(TheBB);
+  }
+
+  explicit IRBuilder(Instruction *IP, MDNode *FPMathTag = nullptr,
+                     ArrayRef<OperandBundleDef> OpBundles = None)
+      : IRBuilderBase(IP->getContext(), this->Folder, this->Inserter,
+                      FPMathTag, OpBundles) {
+    SetInsertPoint(IP);
+  }
+
+  IRBuilder(BasicBlock *TheBB, BasicBlock::iterator IP, FolderTy Folder,
+            MDNode *FPMathTag = nullptr,
+            ArrayRef<OperandBundleDef> OpBundles = None)
+      : IRBuilderBase(TheBB->getContext(), this->Folder, this->Inserter,
+                      FPMathTag, OpBundles), Folder(Folder) {
+    SetInsertPoint(TheBB, IP);
+  }
+
+  IRBuilder(BasicBlock *TheBB, BasicBlock::iterator IP,
+            MDNode *FPMathTag = nullptr,
+            ArrayRef<OperandBundleDef> OpBundles = None)
+      : IRBuilderBase(TheBB->getContext(), this->Folder, this->Inserter,
+                      FPMathTag, OpBundles) {
+    SetInsertPoint(TheBB, IP);
+  }
+
+  InserterTy &getInserter() { return Inserter; }
+};
+
 // Create wrappers for C Binding types (see CBindingWrapping.h).
 DEFINE_SIMPLE_CONVERSION_FUNCTIONS(IRBuilder<>, LLVMBuilderRef)
 
 } // end namespace llvm
 
 #endif // LLVM_IR_IRBUILDER_H

llvm/include/llvm/IR/IRBuilderFolder.h

+//===- IRBuilderFolder.h - Const folder interface for IRBuilder -*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines for constant folding interface used by IRBuilder.
+// It is implemented by ConstantFolder (default), TargetFolder and NoFoler.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_IR_IRBUILDERFOLDER_H
+#define LLVM_IR_IRBUILDERFOLDER_H
+
+#include "llvm/ADT/ArrayRef.h"
+#include "llvm/IR/InstrTypes.h"
+#include "llvm/IR/Instruction.h"
+
+namespace llvm {
+
+/// IRBuilderFolder - Interface for constant folding in IRBuilder.
+class IRBuilderFolder {
+public:
+  //===--------------------------------------------------------------------===//
+  // Binary Operators
+  //===--------------------------------------------------------------------===//
+
+  virtual Value *CreateAdd(Constant *LHS, Constant *RHS,
+                           bool HasNUW = false, bool HasNSW = false) const = 0;
+  virtual Value *CreateFAdd(Constant *LHS, Constant *RHS) const = 0;
+  virtual Value *CreateSub(Constant *LHS, Constant *RHS,
+                           bool HasNUW = false, bool HasNSW = false) const = 0;
+  virtual Value *CreateFSub(Constant *LHS, Constant *RHS) const = 0;
+  virtual Value *CreateMul(Constant *LHS, Constant *RHS,
+                           bool HasNUW = false, bool HasNSW = false) const = 0;
+  virtual Value *CreateFMul(Constant *LHS, Constant *RHS) const = 0;
+  virtual Value *CreateUDiv(Constant *LHS, Constant *RHS,
+                            bool isExact = false) const = 0;
+  virtual Value *CreateSDiv(Constant *LHS, Constant *RHS,
+                            bool isExact = false) const = 0;
+  virtual Value *CreateFDiv(Constant *LHS, Constant *RHS) const = 0;
+  virtual Value *CreateURem(Constant *LHS, Constant *RHS) const = 0;
+  virtual Value *CreateSRem(Constant *LHS, Constant *RHS) const = 0;
+  virtual Value *CreateFRem(Constant *LHS, Constant *RHS) const = 0;
+  virtual Value *CreateShl(Constant *LHS, Constant *RHS,
+                           bool HasNUW = false, bool HasNSW = false) const = 0;
+  virtual Value *CreateLShr(Constant *LHS, Constant *RHS,
+                            bool isExact = false) const = 0;
+  virtual Value *CreateAShr(Constant *LHS, Constant *RHS,
+                            bool isExact = false) const = 0;
+  virtual Value *CreateAnd(Constant *LHS, Constant *RHS) const = 0;
+  virtual Value *CreateOr(Constant *LHS, Constant *RHS) const = 0;
+  virtual Value *CreateXor(Constant *LHS, Constant *RHS) const = 0;
+  virtual Value *CreateBinOp(Instruction::BinaryOps Opc,
+                             Constant *LHS, Constant *RHS) const = 0;
+
+  //===--------------------------------------------------------------------===//
+  // Unary Operators
+  //===--------------------------------------------------------------------===//
+
+  virtual Value *CreateNeg(Constant *C,
+                           bool HasNUW = false, bool HasNSW = false) const = 0;
+  virtual Value *CreateFNeg(Constant *C) const = 0;
+  virtual Value *CreateNot(Constant *C) const = 0;
+  virtual Value *CreateUnOp(Instruction::UnaryOps Opc, Constant *C) const = 0;
+
+  //===--------------------------------------------------------------------===//
+  // Memory Instructions
+  //===--------------------------------------------------------------------===//
+
+  virtual Value *CreateGetElementPtr(Type *Ty, Constant *C,
+                                     ArrayRef<Constant *> IdxList) const = 0;
+  // This form of the function only exists to avoid ambiguous overload
+  // warnings about whether to convert Idx to ArrayRef<Constant *> or
+  // ArrayRef<Value *>.
+  virtual Value *CreateGetElementPtr(Type *Ty, Constant *C,
+                                     Constant *Idx) const = 0;
+  virtual Value *CreateGetElementPtr(Type *Ty, Constant *C,
+                                     ArrayRef<Value *> IdxList) const = 0;
+  virtual Value *CreateInBoundsGetElementPtr(
+      Type *Ty, Constant *C, ArrayRef<Constant *> IdxList) const = 0;
+  // This form of the function only exists to avoid ambiguous overload
+  // warnings about whether to convert Idx to ArrayRef<Constant *> or
+  // ArrayRef<Value *>.
+  virtual Value *CreateInBoundsGetElementPtr(Type *Ty, Constant *C,
+                                             Constant *Idx) const = 0;
+  virtual Value *CreateInBoundsGetElementPtr(
+      Type *Ty, Constant *C, ArrayRef<Value *> IdxList) const = 0;
+
+  //===--------------------------------------------------------------------===//
+  // Cast/Conversion Operators
+  //===--------------------------------------------------------------------===//
+
+  virtual Value *CreateCast(Instruction::CastOps Op, Constant *C,
+                            Type *DestTy) const = 0;
+  virtual Value *CreatePointerCast(Constant *C, Type *DestTy) const = 0;
+  virtual Value *CreatePointerBitCastOrAddrSpaceCast(Constant *C,
+                                                     Type *DestTy) const = 0;
+  virtual Value *CreateIntCast(Constant *C, Type *DestTy,
+                               bool isSigned) const = 0;
+  virtual Value *CreateFPCast(Constant *C, Type *DestTy) const = 0;
+  virtual Value *CreateBitCast(Constant *C, Type *DestTy) const = 0;
+  virtual Value *CreateIntToPtr(Constant *C, Type *DestTy) const = 0;
+  virtual Value *CreatePtrToInt(Constant *C, Type *DestTy) const = 0;
+  virtual Value *CreateZExtOrBitCast(Constant *C, Type *DestTy) const = 0;
+  virtual Value *CreateSExtOrBitCast(Constant *C, Type *DestTy) const = 0;
+  virtual Value *CreateTruncOrBitCast(Constant *C, Type *DestTy) const = 0;
+
+  //===--------------------------------------------------------------------===//
+  // Compare Instructions
+  //===--------------------------------------------------------------------===//
+
+  virtual Value *CreateICmp(CmpInst::Predicate P, Constant *LHS,
+                            Constant *RHS) const = 0;
+  virtual Value *CreateFCmp(CmpInst::Predicate P, Constant *LHS,
+                            Constant *RHS) const = 0;
+
+  //===--------------------------------------------------------------------===//
+  // Other Instructions
+  //===--------------------------------------------------------------------===//
+
+  virtual Value *CreateSelect(Constant *C, Constant *True,
+                              Constant *False) const = 0;
+  virtual Value *CreateExtractElement(Constant *Vec, Constant *Idx) const = 0;
+  virtual Value *CreateInsertElement(Constant *Vec, Constant *NewElt,
+                                     Constant *Idx) const = 0;
+  virtual Value *CreateShuffleVector(Constant *V1, Constant *V2,
+                                     Constant *Mask) const = 0;
+  virtual Value *CreateExtractValue(Constant *Agg,
+                                    ArrayRef<unsigned> IdxList) const = 0;
+  virtual Value *CreateInsertValue(Constant *Agg, Constant *Val,
+                                   ArrayRef<unsigned> IdxList) const = 0;
+};
+
+} // end namespace llvm
+
+#endif // LLVM_IR_IRBUILDERFOLDER_H

llvm/include/llvm/IR/NoFolder.h

 #ifndef LLVM_IR_NOFOLDER_H
 #define LLVM_IR_NOFOLDER_H
 
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/IR/Constants.h"
 #include "llvm/IR/InstrTypes.h"
 #include "llvm/IR/Instruction.h"
 #include "llvm/IR/Instructions.h"
+#include "llvm/IR/IRBuilderFolder.h"
 
 namespace llvm {
 
 /// NoFolder - Create "constants" (actually, instructions) with no folding.
-class NoFolder {
+class NoFolder : public IRBuilderFolder {
+  virtual void anchor();
+
 public:
   explicit NoFolder() = default;
 
   //===--------------------------------------------------------------------===//
   // Binary Operators
   //===--------------------------------------------------------------------===//
 
   Instruction *CreateAdd(Constant *LHS, Constant *RHS,
-                         bool HasNUW = false, bool HasNSW = false) const {
+                         bool HasNUW = false,
+                         bool HasNSW = false) const override {
     BinaryOperator *BO = BinaryOperator::CreateAdd(LHS, RHS);
     if (HasNUW) BO->setHasNoUnsignedWrap();
     if (HasNSW) BO->setHasNoSignedWrap();
     return BO;
   }
 
-  Instruction *CreateFAdd(Constant *LHS, Constant *RHS) const {
+  Instruction *CreateFAdd(Constant *LHS, Constant *RHS) const override {
     return BinaryOperator::CreateFAdd(LHS, RHS);
   }
 
   Instruction *CreateSub(Constant *LHS, Constant *RHS,
-                         bool HasNUW = false, bool HasNSW = false) const {
+                         bool HasNUW = false,
+                         bool HasNSW = false) const override {
     BinaryOperator *BO = BinaryOperator::CreateSub(LHS, RHS);
     if (HasNUW) BO->setHasNoUnsignedWrap();
     if (HasNSW) BO->setHasNoSignedWrap();
     return BO;
   }
 
-  Instruction *CreateFSub(Constant *LHS, Constant *RHS) const {
+  Instruction *CreateFSub(Constant *LHS, Constant *RHS) const override {
     return BinaryOperator::CreateFSub(LHS, RHS);
   }
 
   Instruction *CreateMul(Constant *LHS, Constant *RHS,
-                         bool HasNUW = false, bool HasNSW = false) const {
+                         bool HasNUW = false,
+                         bool HasNSW = false) const override {
     BinaryOperator *BO = BinaryOperator::CreateMul(LHS, RHS);
     if (HasNUW) BO->setHasNoUnsignedWrap();
     if (HasNSW) BO->setHasNoSignedWrap();
     return BO;
   }
 
-  Instruction *CreateFMul(Constant *LHS, Constant *RHS) const {
+  Instruction *CreateFMul(Constant *LHS, Constant *RHS) const override {
     return BinaryOperator::CreateFMul(LHS, RHS);
   }
 
   Instruction *CreateUDiv(Constant *LHS, Constant *RHS,
-                          bool isExact = false) const {
+                          bool isExact = false) const override {
     if (!isExact)
       return BinaryOperator::CreateUDiv(LHS, RHS);
     return BinaryOperator::CreateExactUDiv(LHS, RHS);
   }
 
   Instruction *CreateSDiv(Constant *LHS, Constant *RHS,
-                          bool isExact = false) const {
+                          bool isExact = false) const override {
     if (!isExact)
       return BinaryOperator::CreateSDiv(LHS, RHS);
     return BinaryOperator::CreateExactSDiv(LHS, RHS);
   }
 
-  Instruction *CreateFDiv(Constant *LHS, Constant *RHS) const {
+  Instruction *CreateFDiv(Constant *LHS, Constant *RHS) const override {
     return BinaryOperator::CreateFDiv(LHS, RHS);
   }
 
-  Instruction *CreateURem(Constant *LHS, Constant *RHS) const {
+  Instruction *CreateURem(Constant *LHS, Constant *RHS) const override {
     return BinaryOperator::CreateURem(LHS, RHS);
   }
 
-  Instruction *CreateSRem(Constant *LHS, Constant *RHS) const {
+  Instruction *CreateSRem(Constant *LHS, Constant *RHS) const override {
     return BinaryOperator::CreateSRem(LHS, RHS);
   }
 
-  Instruction *CreateFRem(Constant *LHS, Constant *RHS) const {
+  Instruction *CreateFRem(Constant *LHS, Constant *RHS) const override {
     return BinaryOperator::CreateFRem(LHS, RHS);
   }
 
   Instruction *CreateShl(Constant *LHS, Constant *RHS, bool HasNUW = false,
-                         bool HasNSW = false) const {
+                         bool HasNSW = false) const override {
     BinaryOperator *BO = BinaryOperator::CreateShl(LHS, RHS);
     if (HasNUW) BO->setHasNoUnsignedWrap();
     if (HasNSW) BO->setHasNoSignedWrap();
     return BO;
   }
 
   Instruction *CreateLShr(Constant *LHS, Constant *RHS,
-                          bool isExact = false) const {
+                          bool isExact = false) const override {
     if (!isExact)
       return BinaryOperator::CreateLShr(LHS, RHS);
     return BinaryOperator::CreateExactLShr(LHS, RHS);
   }
 
   Instruction *CreateAShr(Constant *LHS, Constant *RHS,
-                          bool isExact = false) const {
+                          bool isExact = false) const override {
     if (!isExact)
       return BinaryOperator::CreateAShr(LHS, RHS);
     return BinaryOperator::CreateExactAShr(LHS, RHS);
   }
 
-  Instruction *CreateAnd(Constant *LHS, Constant *RHS) const {
+  Instruction *CreateAnd(Constant *LHS, Constant *RHS) const override {
     return BinaryOperator::CreateAnd(LHS, RHS);
   }
 
-  Instruction *CreateOr(Constant *LHS, Constant *RHS) const {
+  Instruction *CreateOr(Constant *LHS, Constant *RHS) const override {
     return BinaryOperator::CreateOr(LHS, RHS);
   }
 
-  Instruction *CreateXor(Constant *LHS, Constant *RHS) const {
+  Instruction *CreateXor(Constant *LHS, Constant *RHS) const override {
     return BinaryOperator::CreateXor(LHS, RHS);
   }
 
   Instruction *CreateBinOp(Instruction::BinaryOps Opc,
-                           Constant *LHS, Constant *RHS) const {
+                           Constant *LHS, Constant *RHS) const override {
     return BinaryOperator::Create(Opc, LHS, RHS);
   }
 
   //===--------------------------------------------------------------------===//
   // Unary Operators
   //===--------------------------------------------------------------------===//
 
   Instruction *CreateNeg(Constant *C,
-                         bool HasNUW = false, bool HasNSW = false) const {
+                         bool HasNUW = false,
+                         bool HasNSW = false) const override {
     BinaryOperator *BO = BinaryOperator::CreateNeg(C);
     if (HasNUW) BO->setHasNoUnsignedWrap();
     if (HasNSW) BO->setHasNoSignedWrap();
     return BO;
   }
 
-  Instruction *CreateFNeg(Constant *C) const {
+  Instruction *CreateFNeg(Constant *C) const override {
     return UnaryOperator::CreateFNeg(C);
   }
 
-  Instruction *CreateNot(Constant *C) const {
+  Instruction *CreateNot(Constant *C) const override {
     return BinaryOperator::CreateNot(C);
   }
 
-  Instruction *CreateUnOp(Instruction::UnaryOps Opc, Constant *C) const {
+  Instruction *CreateUnOp(Instruction::UnaryOps Opc,
+                          Constant *C) const override {
     return UnaryOperator::Create(Opc, C);
   }
 
   //===--------------------------------------------------------------------===//
   // Memory Instructions
   //===--------------------------------------------------------------------===//
 
   Constant *CreateGetElementPtr(Type *Ty, Constant *C,
-                                ArrayRef<Constant *> IdxList) const {
+                                ArrayRef<Constant *> IdxList) const override {
     return ConstantExpr::getGetElementPtr(Ty, C, IdxList);
   }
 
-  Constant *CreateGetElementPtr(Type *Ty, Constant *C, Constant *Idx) const {
+  Constant *CreateGetElementPtr(Type *Ty, Constant *C,
+                                Constant *Idx) const override {
     // This form of the function only exists to avoid ambiguous overload
     // warnings about whether to convert Idx to ArrayRef<Constant *> or
     // ArrayRef<Value *>.
     return ConstantExpr::getGetElementPtr(Ty, C, Idx);
   }
 
   Instruction *CreateGetElementPtr(Type *Ty, Constant *C,
-                                   ArrayRef<Value *> IdxList) const {
+                                   ArrayRef<Value *> IdxList) const override {
     return GetElementPtrInst::Create(Ty, C, IdxList);
   }
 
-  Constant *CreateInBoundsGetElementPtr(Type *Ty, Constant *C,
-                                        ArrayRef<Constant *> IdxList) const {
+  Constant *CreateInBoundsGetElementPtr(
+      Type *Ty, Constant *C, ArrayRef<Constant *> IdxList) const override {
     return ConstantExpr::getInBoundsGetElementPtr(Ty, C, IdxList);
   }
 
   Constant *CreateInBoundsGetElementPtr(Type *Ty, Constant *C,
-                                        Constant *Idx) const {
+                                        Constant *Idx) const override {
     // This form of the function only exists to avoid ambiguous overload
     // warnings about whether to convert Idx to ArrayRef<Constant *> or
     // ArrayRef<Value *>.
     return ConstantExpr::getInBoundsGetElementPtr(Ty, C, Idx);
   }
 
-  Instruction *CreateInBoundsGetElementPtr(Type *Ty, Constant *C,
-                                           ArrayRef<Value *> IdxList) const {
+  Instruction *CreateInBoundsGetElementPtr(
+      Type *Ty, Constant *C, ArrayRef<Value *> IdxList) const override {
     return GetElementPtrInst::CreateInBounds(Ty, C, IdxList);
   }
 
   //===--------------------------------------------------------------------===//
   // Cast/Conversion Operators
   //===--------------------------------------------------------------------===//
 
   Instruction *CreateCast(Instruction::CastOps Op, Constant *C,
-                    Type *DestTy) const {
+                          Type *DestTy) const override {
     return CastInst::Create(Op, C, DestTy);
   }
 
-  Instruction *CreatePointerCast(Constant *C, Type *DestTy) const {
+  Instruction *CreatePointerCast(Constant *C, Type *DestTy) const override {
     return CastInst::CreatePointerCast(C, DestTy);
   }
 
   Instruction *CreatePointerBitCastOrAddrSpaceCast(
-      Constant *C, Type *DestTy) const {
+      Constant *C, Type *DestTy) const override {
     return CastInst::CreatePointerBitCastOrAddrSpaceCast(C, DestTy);
   }
 
   Instruction *CreateIntCast(Constant *C, Type *DestTy,
-                       bool isSigned) const {
+                             bool isSigned) const override {
     return CastInst::CreateIntegerCast(C, DestTy, isSigned);
   }
 
-  Instruction *CreateFPCast(Constant *C, Type *DestTy) const {
+  Instruction *CreateFPCast(Constant *C, Type *DestTy) const override {
     return CastInst::CreateFPCast(C, DestTy);
   }
 
-  Instruction *CreateBitCast(Constant *C, Type *DestTy) const {
+  Instruction *CreateBitCast(Constant *C, Type *DestTy) const override {
     return CreateCast(Instruction::BitCast, C, DestTy);
   }
 
-  Instruction *CreateIntToPtr(Constant *C, Type *DestTy) const {
+  Instruction *CreateIntToPtr(Constant *C, Type *DestTy) const override {
     return CreateCast(Instruction::IntToPtr, C, DestTy);
   }
 
-  Instruction *CreatePtrToInt(Constant *C, Type *DestTy) const {
+  Instruction *CreatePtrToInt(Constant *C, Type *DestTy) const override {
     return CreateCast(Instruction::PtrToInt, C, DestTy);
   }
 
-  Instruction *CreateZExtOrBitCast(Constant *C, Type *DestTy) const {
+  Instruction *CreateZExtOrBitCast(Constant *C, Type *DestTy) const override {
     return CastInst::CreateZExtOrBitCast(C, DestTy);
   }
 
-  Instruction *CreateSExtOrBitCast(Constant *C, Type *DestTy) const {
+  Instruction *CreateSExtOrBitCast(Constant *C, Type *DestTy) const override {
     return CastInst::CreateSExtOrBitCast(C, DestTy);
   }
 
-  Instruction *CreateTruncOrBitCast(Constant *C, Type *DestTy) const {
+  Instruction *CreateTruncOrBitCast(Constant *C, Type *DestTy) const override {
     return CastInst::CreateTruncOrBitCast(C, DestTy);
   }
 
   //===--------------------------------------------------------------------===//
   // Compare Instructions
   //===--------------------------------------------------------------------===//
 
   Instruction *CreateICmp(CmpInst::Predicate P,
-                          Constant *LHS, Constant *RHS) const {
+                          Constant *LHS, Constant *RHS) const override {
     return new ICmpInst(P, LHS, RHS);
   }
 
   Instruction *CreateFCmp(CmpInst::Predicate P,
-                          Constant *LHS, Constant *RHS) const {
+                          Constant *LHS, Constant *RHS) const override {
     return new FCmpInst(P, LHS, RHS);
   }
 
   //===--------------------------------------------------------------------===//
   // Other Instructions
   //===--------------------------------------------------------------------===//
 
   Instruction *CreateSelect(Constant *C,
-                            Constant *True, Constant *False) const {
+                            Constant *True, Constant *False) const override {
     return SelectInst::Create(C, True, False);
   }
 
-  Instruction *CreateExtractElement(Constant *Vec, Constant *Idx) const {
+  Instruction *CreateExtractElement(Constant *Vec,
+                                    Constant *Idx) const override {
     return ExtractElementInst::Create(Vec, Idx);
   }
 
   Instruction *CreateInsertElement(Constant *Vec, Constant *NewElt,
-                                   Constant *Idx) const {
+                                   Constant *Idx) const override {
     return InsertElementInst::Create(Vec, NewElt, Idx);
   }
 
   Instruction *CreateShuffleVector(Constant *V1, Constant *V2,
-                                   Constant *Mask) const {
+                                   Constant *Mask) const override {
     return new ShuffleVectorInst(V1, V2, Mask);
   }
 
   Instruction *CreateExtractValue(Constant *Agg,
-                                  ArrayRef<unsigned> IdxList) const {
+                                  ArrayRef<unsigned> IdxList) const override {
     return ExtractValueInst::Create(Agg, IdxList);
   }
 
   Instruction *CreateInsertValue(Constant *Agg, Constant *Val,
-                                 ArrayRef<unsigned> IdxList) const {
+                                 ArrayRef<unsigned> IdxList) const override {
     return InsertValueInst::Create(Agg, Val, IdxList);
   }
 };
 
 } // end namespace llvm
 
 #endif // LLVM_IR_NOFOLDER_H

llvm/lib/Analysis/ConstantFolding.cpp

 #include "llvm/Analysis/ConstantFolding.h"
 #include "llvm/ADT/APFloat.h"
 #include "llvm/ADT/APInt.h"
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/StringRef.h"
+#include "llvm/Analysis/TargetFolder.h"
 #include "llvm/Analysis/TargetLibraryInfo.h"
 #include "llvm/Analysis/ValueTracking.h"
 #include "llvm/Analysis/VectorUtils.h"
 #include "llvm/Config/config.h"
 #include "llvm/IR/Constant.h"
 #include "llvm/IR/Constants.h"
 #include "llvm/IR/DataLayout.h"
 #include "llvm/IR/DerivedTypes.h"
if (Op0C && Op1C) {
       default:
         break;
       }
     }
   }
 
   return false;
 }
+
+void TargetFolder::anchor() {}

llvm/lib/IR/IRBuilder.cpp

 #include "llvm/IR/DerivedTypes.h"
 #include "llvm/IR/Function.h"
 #include "llvm/IR/GlobalValue.h"
 #include "llvm/IR/GlobalVariable.h"
 #include "llvm/IR/IntrinsicInst.h"
 #include "llvm/IR/Intrinsics.h"
 #include "llvm/IR/LLVMContext.h"
 #include "llvm/IR/Operator.h"
+#include "llvm/IR/NoFolder.h"
 #include "llvm/IR/Statepoint.h"
 #include "llvm/IR/Type.h"
 #include "llvm/IR/Value.h"
 #include "llvm/Support/Casting.h"
 #include "llvm/Support/MathExtras.h"
 #include <cassert>
 #include <cstdint>
 #include <vector>
CallInst *IRBuilderBase::CreateIntrinsic(Intrinsic::ID ID,
                                          ArrayRef<Type *> Types,
                                          ArrayRef<Value *> Args,
                                          Instruction *FMFSource,
                                          const Twine &Name) {
   Module *M = BB->getModule();
   Function *Fn = Intrinsic::getDeclaration(M, ID, Types);
   return createCallHelper(Fn, Args, this, Name, FMFSource);
 }
+
+void IRBuilderDefaultInserter::anchor() {}
+void IRBuilderCallbackInserter::anchor() {}
+void ConstantFolder::anchor() {}
+void NoFolder::anchor() {}

llvm/lib/Transforms/Scalar/SROA.cpp

class IRBuilderPrefixedInserter : public IRBuilderDefaultInserter {
 
   const Twine getNameWithPrefix(const Twine &Name) const {
     return Name.isTriviallyEmpty() ? Name : Prefix + Name;
   }
 
 public:
   void SetNamePrefix(const Twine &P) { Prefix = P.str(); }
 
-protected:
   void InsertHelper(Instruction *I, const Twine &Name, BasicBlock *BB,
-                    BasicBlock::iterator InsertPt) const {
+                    BasicBlock::iterator InsertPt) const override {
     IRBuilderDefaultInserter::InsertHelper(I, getNameWithPrefix(Name), BB,
                                            InsertPt);
   }
 };
 
 /// Provide a type for IRBuilder that drops names in release builds.
 using IRBuilderTy = IRBuilder<ConstantFolder, IRBuilderPrefixedInserter>;
 
bool visit(AllocaSlices::const_iterator I) {
     SliceSize = NewEndOffset - NewBeginOffset;
 
     OldUse = I->getUse();
     OldPtr = cast<Instruction>(OldUse->get());
 
     Instruction *OldUserI = cast<Instruction>(OldUse->getUser());
     IRB.SetInsertPoint(OldUserI);
     IRB.SetCurrentDebugLocation(OldUserI->getDebugLoc());
-    IRB.SetNamePrefix(Twine(NewAI.getName()) + "." + Twine(BeginOffset) + ".");
+    IRB.getInserter().SetNamePrefix(
+        Twine(NewAI.getName()) + "." + Twine(BeginOffset) + ".");
 
     CanSROA &= visit(cast<Instruction>(OldUse->getUser()));
     if (VecTy || IntTy)
       assert(CanSROA);
     return CanSROA;
   }
 
 private:

polly/include/polly/CodeGen/IRBuilder.h

private:
   llvm::DenseMap<llvm::AssertingVH<llvm::Value>, llvm::AssertingVH<llvm::Value>>
       AlternativeAliasBases;
 };
 
 /// Add Polly specifics when running IRBuilder.
 ///
 /// This is used to add additional items such as e.g. the llvm.loop.parallel
 /// metadata.
-class IRInserter : protected llvm::IRBuilderDefaultInserter {
+class IRInserter : public llvm::IRBuilderDefaultInserter {
 public:
   IRInserter() = default;
   IRInserter(class ScopAnnotator &A) : Annotator(&A) {}
 
-protected:
   void InsertHelper(llvm::Instruction *I, const llvm::Twine &Name,
                     llvm::BasicBlock *BB,
-                    llvm::BasicBlock::iterator InsertPt) const {
+                    llvm::BasicBlock::iterator InsertPt) const override {
     llvm::IRBuilderDefaultInserter::InsertHelper(I, Name, BB, InsertPt);
     if (Annotator)
       Annotator->annotate(I);
   }
 
 private:
   class ScopAnnotator *Annotator = nullptr;
 };