Constant propogation through freeze instruction

[mgudim]

Summary

The freeze instruction has not been handled by SCCPInstVisitor. This patch adds SCCPInstVisitor::visitFreezeInst(FreezeInst &I) method to handle freeze instructions.

[nikic]

You need to ensure the constant is not potentially undef or poison.

[mgudim]

@nikic Thanks for taking a look!

My understanding is that if the argument of freeze instruction is undef then V0State.isUnknownOrUndef() will return true and we exit. In the value lattice undef and constant are separate states (llvm-project/llvm/include/llvm/Analysis/ValueLattice.h : 45)
Also, the test checks that freeze instructions with undef argument remain untouched %fr = freeze i32 undef - the test passed with my change.

I have also tested with poison: the instruction %fr = freeze i32 poison remains untouched. (but we could return any i32 value, according to semantics of freeze) Does this look right? Or am I still misunderstanding?

[nikic]

The value lattice only distinguishes literal undef values. You can still have a constant that is potentially poison. Try something like freeze i64 add nuw (i64 ptrtoint (ptr @g to i64), i64 123).

[mgudim]

Added the check for potentially poison values.

[mgudim]

@nikic Thanks for explaining, I understand now. The check was necessary for the test case you suggested. I've updated the diff and included your test case.

[nikic]

LGTM

[fhahn]

LGTM, thanks!

llvm/lib/Transforms/Utils/SCCPSolver.cpp

1422

nit: fold into previous if?

[mgudim]

Merged nested ifs into one.

[mgudim]

@fhahn @nikic Can someone please merge this patch for me? I don't have commit rights yet.

[mgudim]

Build passed.

[nikic]

Can you please share which Name <email> to use for attribution on the commit?

[mgudim]

Can you please share which Name <email> to use for attribution on the commit?

Mikhail Gudim <[e-mail]>

[nikic]

Reverted due to buildbot failure:

FAILED: lib/TableGen/CMakeFiles/LLVMTableGen.dir/SetTheory.cpp.o
CCACHE_CPP2=yes CCACHE_HASHDIR=yes /usr/bin/ccache /b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm_build0/bin/clang++ -DGTEST_HAS_RTTI=0 -D_DEBUG -D_GLIBCXX_ASSERTIONS -D_GNU_SOURCE -D_LIBCPP_ENABLE_ASSERTIONS -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -I/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm_build_ubsan/lib/TableGen -I/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm-project/llvm/lib/TableGen -I/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm_build_ubsan/include -I/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm-project/llvm/include -nostdinc++ -isystem /b/sanitizer-aarch64-linux-bootstrap-ubsan/build/libcxx_build_ubsan/include -isystem /b/sanitizer-aarch64-linux-bootstrap-ubsan/build/libcxx_build_ubsan/include/c++/v1 -fsanitize=undefined -Wl,--rpath=/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/libcxx_build_ubsan/lib -L/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/libcxx_build_ubsan/lib -w -stdlib=libc++ -fPIC -fno
 -semantic-interposition -fvisibility-inlines-hidden -Werror=date-time -Werror=unguarded-availability-new -Wall -Wextra -Wno-unused-parameter -Wwrite-strings -Wcast-qual -Wmissing-field-initializers -pedantic -Wno-long-long -Wc++98-compat-extra-semi -Wimplicit-fallthrough -Wcovered-switch-default -Wno-class-memaccess -Wno-noexcept-type -Wnon-virtual-dtor -Wdelete-non-virtual-dtor -Wsuggest-override -Wstring-conversion -Wmisleading-indentation -Wctad-maybe-unsupported -fno-omit-frame-pointer -gline-tables-only -fsanitize=undefined -fno-sanitize=vptr,function -fno-sanitize-recover=all -fsanitize-blacklist=/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm-project/llvm/utils/sanitizers/ubsan_ignorelist.txt -fdiagnostics-color -ffunction-sections -fdata-sections -O3 -DNDEBUG  -fno-exceptions -funwind-tables -fno-rtti -UNDEBUG -std=c++17 -MD -MT lib/TableGen/CMakeFiles/LLVMTableGen.dir/SetTheory.cpp.o -MF lib/TableGen/CMakeFiles/LLVMTableGen.dir/SetTheory.cpp.o.d -o lib/TableGen/CMakeF
 iles/LLVMTableGen.dir/SetTheory.cpp.o -c /b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm-project/llvm/lib/TableGen/SetTheory.cpp
clang++: /b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm-project/llvm/lib/Transforms/Utils/SCCPSolver.cpp:442: llvm::ValueLatticeElement &llvm::SCCPInstVisitor::getValueState(llvm::Value *): Assertion `!V->getType()->isStructTy() && "Should use getStructValueState"' failed.
PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace, preprocessed source, and associated run script.
Stack dump:
0.      Program arguments: /b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm_build0/bin/clang++ -fsanitize=undefined -L/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/libcxx_build_ubsan/lib -w -fPIC -fno-semantic-interposition -fvisibility-inlines-hidden -Werror=date-time -Werror=unguarded-availability-new -Wall -Wextra -Wno-unused-parameter -Wwrite-strings -Wcast-qual -Wmissing-field-initializers -pedantic -Wno-long-long -Wc++98-compat-extra-semi -Wimplicit-fallthrough -Wcovered-switch-default -Wno-class-memaccess -Wno-noexcept-type -Wnon-virtual-dtor -Wdelete-non-virtual-dtor -Wsuggest-override -Wstring-conversion -Wmisleading-indentation -Wctad-maybe-unsupported -fno-omit-frame-pointer -gline-tables-only -fsanitize=undefined -fno-sanitize=vptr,function -fno-sanitize-recover=all -fsanitize-blacklist=/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm-project/llvm/utils/sanitizers/ubsan_ignorelist.txt -ffunction-sections -fdata-sections -O3 -fno-exceptions -funwind-tables -fno-rtt
 i -std=c++17 -fdiagnostics-color -Wl,--rpath=/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/libcxx_build_ubsan/lib -DGTEST_HAS_RTTI=0 -D_DEBUG -D_GLIBCXX_ASSERTIONS -D_GNU_SOURCE -D_LIBCPP_ENABLE_ASSERTIONS -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -I/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm_build_ubsan/lib/TableGen -I/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm-project/llvm/lib/TableGen -I/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm_build_ubsan/include -I/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm-project/llvm/include -nostdinc++ -isystem /b/sanitizer-aarch64-linux-bootstrap-ubsan/build/libcxx_build_ubsan/include -isystem /b/sanitizer-aarch64-linux-bootstrap-ubsan/build/libcxx_build_ubsan/include/c++/v1 -stdlib=libc++ -DNDEBUG -UNDEBUG -c -MD -MT lib/TableGen/CMakeFiles/LLVMTableGen.dir/SetTheory.cpp.o -MF lib/TableGen/CMakeFiles/LLVMTableGen.dir/SetTheory.cpp.o.d -fcolor-diagnostics -o lib/TableGen/CMakeFiles/LL
 VMTableGen.dir/SetTheory.cpp.o /b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm-project/llvm/lib/TableGen/SetTheory.cpp
1.      <eof> parser at end of file
2.      Optimizer
 #0 0x0000aaaad4f56648 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm_build0/bin/clang+++0x7606648)
 #1 0x0000aaaad4f547a8 llvm::sys::RunSignalHandlers() (/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm_build0/bin/clang+++0x76047a8)
 #2 0x0000aaaad4ec6ab4 CrashRecoverySignalHandler(int) CrashRecoveryContext.cpp:0:0
 #3 0x0000ffffb1d768bc (linux-vdso.so.1+0x8bc)
 #4 0x0000ffffb18610c0 (/lib/aarch64-linux-gnu/libc.so.6+0x810c0)
 #5 0x0000ffffb181ab2c raise (/lib/aarch64-linux-gnu/libc.so.6+0x3ab2c)
 #6 0x0000ffffb18074bc abort (/lib/aarch64-linux-gnu/libc.so.6+0x274bc)
 #7 0x0000ffffb1814434 (/lib/aarch64-linux-gnu/libc.so.6+0x34434)
 #8 0x0000ffffb181449c (/lib/aarch64-linux-gnu/libc.so.6+0x3449c)
 #9 0x0000aaaad62c2634 llvm::SCCPInstVisitor::getValueState(llvm::Value*) SCCPSolver.cpp:0:0
#10 0x0000aaaad62c5664 llvm::SCCPInstVisitor::visitFreezeInst(llvm::FreezeInst&) (/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm_build0/bin/clang+++0x8975664)
#11 0x0000aaaad62c9a8c llvm::SCCPInstVisitor::solve() (/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm_build0/bin/clang+++0x8979a8c)
#12 0x0000aaaad63b56ec llvm::SCCPPass::run(llvm::Function&, llvm::AnalysisManager<llvm::Function>&) (/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm_build0/bin/clang+++0x8a656ec)
#13 0x0000aaaad49cf3ac llvm::PassManager<llvm::Function, llvm::AnalysisManager<llvm::Function>>::run(llvm::Function&, llvm::AnalysisManager<llvm::Function>&) (/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm_build0/bin/clang+++0x707f3ac)
#14 0x0000aaaad40c5bd0 llvm::CGSCCToFunctionPassAdaptor::run(llvm::LazyCallGraph::SCC&, llvm::AnalysisManager<llvm::LazyCallGraph::SCC, llvm::LazyCallGraph&>&, llvm::LazyCallGraph&, llvm::CGSCCUpdateResult&) (/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm_build0/bin/clang+++0x6775bd0)
#15 0x0000aaaad40c0b80 llvm::PassManager<llvm::LazyCallGraph::SCC, llvm::AnalysisManager<llvm::LazyCallGraph::SCC, llvm::LazyCallGraph&>, llvm::LazyCallGraph&, llvm::CGSCCUpdateResult&>::run(llvm::LazyCallGraph::SCC&, llvm::AnalysisManager<llvm::LazyCallGraph::SCC, llvm::LazyCallGraph&>&, llvm::LazyCallGraph&, llvm::CGSCCUpdateResult&) (/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm_build0/bin/clang+++0x6770b80)
#16 0x0000aaaad40c41a8 llvm::DevirtSCCRepeatedPass::run(llvm::LazyCallGraph::SCC&, llvm::AnalysisManager<llvm::LazyCallGraph::SCC, llvm::LazyCallGraph&>&, llvm::LazyCallGraph&, llvm::CGSCCUpdateResult&) (/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm_build0/bin/clang+++0x67741a8)
#17 0x0000aaaad40c2960 llvm::ModuleToPostOrderCGSCCPassAdaptor::run(llvm::Module&, llvm::AnalysisManager<llvm::Module>&) (/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm_build0/bin/clang+++0x6772960)
#18 0x0000aaaad49ce6ac llvm::PassManager<llvm::Module, llvm::AnalysisManager<llvm::Module>>::run(llvm::Module&, llvm::AnalysisManager<llvm::Module>&) (/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm_build0/bin/clang+++0x707e6ac)
#19 0x0000aaaad61e3a88 llvm::ModuleInlinerWrapperPass::run(llvm::Module&, llvm::AnalysisManager<llvm::Module>&) (/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm_build0/bin/clang+++0x8893a88)
#20 0x0000aaaad49ce6ac llvm::PassManager<llvm::Module, llvm::AnalysisManager<llvm::Module>>::run(llvm::Module&, llvm::AnalysisManager<llvm::Module>&) (/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm_build0/bin/clang+++0x707e6ac)
#21 0x0000aaaad564a520 (anonymous namespace)::EmitAssemblyHelper::RunOptimizationPipeline(clang::BackendAction, std::unique_ptr<llvm::raw_pwrite_stream, std::default_delete<llvm::raw_pwrite_stream>>&, std::unique_ptr<llvm::ToolOutputFile, std::default_delete<llvm::ToolOutputFile>>&) BackendUtil.cpp:0:0
#22 0x0000aaaad56430f4 clang::EmitBackendOutput(clang::DiagnosticsEngine&, clang::HeaderSearchOptions const&, clang::CodeGenOptions const&, clang::TargetOptions const&, clang::LangOptions const&, llvm::StringRef, llvm::Module*, clang::BackendAction, llvm::IntrusiveRefCntPtr<llvm::vfs::FileSystem>, std::unique_ptr<llvm::raw_pwrite_stream, std::default_delete<llvm::raw_pwrite_stream>>) (/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm_build0/bin/clang+++0x7cf30f4)
#23 0x0000aaaad5a45474 clang::BackendConsumer::HandleTranslationUnit(clang::ASTContext&) CodeGenAction.cpp:0:0
#24 0x0000aaaad7039f5c clang::ParseAST(clang::Sema&, bool, bool) (/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm_build0/bin/clang+++0x96e9f5c)
#25 0x0000aaaad5963f8c clang::FrontendAction::Execute() (/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm_build0/bin/clang+++0x8013f8c)
#26 0x0000aaaad58e8894 clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) (/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm_build0/bin/clang+++0x7f98894)
#27 0x0000aaaad5a3f09c clang::ExecuteCompilerInvocation(clang::CompilerInstance*) (/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm_build0/bin/clang+++0x80ef09c)
#28 0x0000aaaad2d3f560 cc1_main(llvm::ArrayRef<char const*>, char const*, void*) (/b/sanitizer-aarch64-linux-bootstrap-ubsan/build/llvm_build0/bin/clang+++0x53ef560)
#29 0x0000aaaad2d3b530 ExecuteCC1Tool(llvm::SmallVectorImpl<char const*>&, llvm::ToolContext const&) driver.cpp:0:0
#30 0x0000aaaad57b7b18 void llvm::function_ref<void ()>::callback_fn<clang::driver::CC1Command::Execute(llvm::ArrayRef<std::optional<llvm::StringRef>>, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char>>*, bool*) const::$_1>(long) Job.cpp:0:0

[mgudim]

Added a check if type is struct (followed visitSelect as an example)
added test freeze_struct

[mgudim]

there is this failure on windows:

$ ":" "RUN: at line 1"
$ "c:\users\tcwg\llvm-worker\clang-arm64-windows-msvc-2stage\stage1\bin\flang-new.exe" "-S" "-emit-llvm" "-o" "-" "C:\Users\tcwg\llvm-worker\clang-arm64-windows-msvc-2stage\llvm\flang\test\Driver\compiler_options.f90"
$ "c:\users\tcwg\llvm-worker\clang-arm64-windows-msvc-2stage\stage1\bin\filecheck.exe" "C:\Users\tcwg\llvm-worker\clang-arm64-windows-msvc-2stage\llvm\flang\test\Driver\compiler_options.f90"
# command stderr:
C:\Users\tcwg\llvm-worker\clang-arm64-windows-msvc-2stage\llvm\flang\test\Driver\compiler_options.f90:3:10: error: CHECK: expected string not found in input
! CHECK: [[OPTSVAR:@_QQcl\.[0-9a-f]+]] = linkonce constant [[[OPTSLEN:[0-9]+]] x i8] c"{{.*}}flang-new{{(\.exe)?}} -S -emit-llvm -o - {{.*}}compiler_options.f90"
         ^
<stdin>:1:1: note: scanning from here
; ModuleID = 'FIRModule'
^

Input file: <stdin>
Check file: C:\Users\tcwg\llvm-worker\clang-arm64-windows-msvc-2stage\llvm\flang\test\Driver\compiler_options.f90

-dump-input=help explains the following input dump.

Input was:
<<<<<<
         1: ; ModuleID = 'FIRModule'
check:3     X~~~~~~~~~~~~~~~~~~~~~~~~ error: no match found
         2: source_filename = "FIRModule"
check:3     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
         3: target datalayout = "e-m:w-p:64:64-i32:32-i64:64-i128:128-n32:64-S128"
check:3     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
         4: target triple = "aarch64-pc-windows-msvc19.34.31937"
check:3     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
         5: 
check:3     ~
         6: @_QQcl.46849559950f708ee332311df8227b62 = internal constant [203 x i8] c"c:\\users\\tcwg\\llvm-worker\\clang-arm64-windows-msvc-2stage\\stage1\\bin\\flang-new.exe -S -emit-llvm -o - C:\\Users\\tcwg\\llvm-worker\\clang-arm64-windows-msvc-2stage\\llvm\\flang\\test\\Driver\\compiler_options.f90"
check:3     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
         .
         .
         .
>>>>>>

error: command failed with exit status: 1

Any ideas what this may be? Seems like test is expecting "linkonce" but instead it finds "internal". How can this be related to my change? Was it a known failure? Is there a way to check?

[mgudim]

Is there a way to trigger all the tests before merging?

llvm/lib/Transforms/Utils/SCCPSolver.cpp

 //
 //===----------------------------------------------------------------------===//
 
 #include "llvm/Transforms/Utils/SCCPSolver.h"
 #include "llvm/Analysis/ConstantFolding.h"
 #include "llvm/Analysis/InstructionSimplify.h"
 #include "llvm/Analysis/ValueLattice.h"
 #include "llvm/Analysis/ValueLatticeUtils.h"
+#include "llvm/Analysis/ValueTracking.h"
 #include "llvm/IR/InstVisitor.h"
 #include "llvm/Support/Casting.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/raw_ostream.h"
 #include "llvm/Transforms/Utils/Local.h"
 #include <cassert>
 #include <utility>
private:
   // Terminators
 
   void visitReturnInst(ReturnInst &I);
   void visitTerminator(Instruction &TI);
 
   void visitCastInst(CastInst &I);
   void visitSelectInst(SelectInst &I);
   void visitUnaryOperator(Instruction &I);
+  void visitFreezeInst(FreezeInst &I);
   void visitBinaryOperator(Instruction &I);
   void visitCmpInst(CmpInst &I);
   void visitExtractValueInst(ExtractValueInst &EVI);
   void visitInsertValueInst(InsertValueInst &IVI);
 
   void visitCatchSwitchInst(CatchSwitchInst &CPI) {
     markOverdefined(&CPI);
     visitTerminator(CPI);
void SCCPInstVisitor::visitUnaryOperator(Instruction &I) {
   if (SCCPSolver::isConstant(V0State))
     if (Constant *C = ConstantFoldUnaryOpOperand(I.getOpcode(),
                                                  getConstant(V0State), DL))
       return (void)markConstant(IV, &I, C);
 
   markOverdefined(&I);
 }
 
+void SCCPInstVisitor::visitFreezeInst(FreezeInst &I) {
+  // If this freeze returns a struct, just mark the result overdefined.
+  // TODO: We could do a lot better than this.
+  if (I.getType()->isStructTy())
+    return (void)markOverdefined(&I);
+
+  ValueLatticeElement V0State = getValueState(I.getOperand(0));
+  ValueLatticeElement &IV = ValueState[&I];
+  // resolvedUndefsIn might mark I as overdefined. Bail out, even if we would
+  // discover a concrete value later.
+  if (SCCPSolver::isOverdefined(IV))
+    return (void)markOverdefined(&I);
+
+  // If something is unknown/undef, wait for it to resolve.
+  if (V0State.isUnknownOrUndef())
+    return;
+
+  if (SCCPSolver::isConstant(V0State) &&
+      isGuaranteedNotToBeUndefOrPoison(getConstant(V0State)))
+    return (void)markConstant(IV, &I, getConstant(V0State));
+
+  markOverdefined(&I);
+}
+
 // Handle Binary Operators.
 void SCCPInstVisitor::visitBinaryOperator(Instruction &I) {
   ValueLatticeElement V1State = getValueState(I.getOperand(0));
   ValueLatticeElement V2State = getValueState(I.getOperand(1));
 
   ValueLatticeElement &IV = ValueState[&I];
   if (IV.isOverdefined())
     return;

llvm/test/Transforms/SCCP/freeze.ll

 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
 ; RUN: opt -passes=ipsccp -S %s | FileCheck %s
 
+@g = global i64 0
 declare void @use(i1)
 
 define i1 @freeze_undef_i1() {
 ; CHECK-LABEL: @freeze_undef_i1(
 ; CHECK-NEXT:    [[FR:%.*]] = freeze i1 undef
 ; CHECK-NEXT:    ret i1 [[FR]]
 ;
   %fr = freeze i1 undef

 ; CHECK-LABEL: @freeze_undef_vector(
 ; CHECK-NEXT:    [[FR:%.*]] = freeze <2 x i32> undef
 ; CHECK-NEXT:    ret <2 x i32> [[FR]]
 ;
   %fr = freeze <2 x i32> undef
   ret <2 x i32> %fr
 }
 
+define i1 @freeze_const_i1() {
+; CHECK-LABEL: @freeze_const_i1(
+; CHECK-NEXT:    ret i1 true
+;
+  %fr = freeze i1 1
+  ret i1 %fr
+}
+
+define ptr @freeze_const_ptr() {
+; CHECK-LABEL: @freeze_const_ptr(
+; CHECK-NEXT:    ret ptr inttoptr (i32 256 to ptr)
+;
+  %fr = freeze ptr inttoptr (i32 256 to ptr)
+  ret ptr %fr
+}
+
+define float @freeze_const_float() {
+; CHECK-LABEL: @freeze_const_float(
+; CHECK-NEXT:    ret float 2.500000e-01
+;
+  %fr = freeze float 2.500000e-01
+  ret float %fr
+}
+
+define <2 x i32> @freeze_const_vector() {
+; CHECK-LABEL: @freeze_const_vector(
+; CHECK-NEXT:    ret <2 x i32> <i32 1, i32 2>
+;
+  %fr = freeze <2 x i32> <i32 1, i32 2>
+  ret <2 x i32> %fr
+}
+
+; make sure we don't constant-propagate values that could potentially be poison
+define i64 @maybe_poison() {
+; CHECK-LABEL: @maybe_poison(
+; CHECK-NEXT:    [[FR:%.*]] = freeze i64 add nuw (i64 ptrtoint (ptr @g to i64), i64 123)
+; CHECK-NEXT:    ret i64 [[FR]]
+;
+  %fr = freeze i64 add nuw (i64 ptrtoint (ptr @g to i64), i64 123)
+  ret i64 %fr
+}
+
+define {i64, i64} @freeze_struct({i64, i64} %s) {
+; CHECK-LABEL: @freeze_struct(
+; CHECK-NEXT:    [[FR:%.*]] = freeze { i64, i64 } [[S:%.*]]
+; CHECK-NEXT:    ret { i64, i64 } [[FR]]
+;
+  %fr = freeze {i64, i64} %s
+  ret {i64, i64} %fr
+}
+
 define i1 @propagate_range_from_and_through_freeze(i32 %x, i32 %y) {
 ; CHECK-LABEL: @propagate_range_from_and_through_freeze(
 ; CHECK-NEXT:    [[AND:%.*]] = and i32 [[X:%.*]], 3
 ; CHECK-NEXT:    [[AND_FR:%.*]] = freeze i32 [[AND]]
 ; CHECK-NEXT:    [[F_1:%.*]] = icmp eq i32 [[AND_FR]], 100
 ; CHECK-NEXT:    call void @use(i1 [[F_1]])
 ; CHECK-NEXT:    [[T_1:%.*]] = icmp ule i32 [[AND_FR]], 3
 ; CHECK-NEXT:    call void @use(i1 [[T_1]])