Introduce print-memderefs to test isDereferenceablePointer

[artagnon]

Summary

Since testing the function indirectly is tricky, introduce a direct
print-memderefs pass, in the same spirit as print-memdeps, which prints
dereferenceability information matched by FileCheck.

[reames]

I'd suggest splitting this into two patches: adding the new analysis, adding the new optimization and testing it. If you really didn't want to for some reason, it's not that big a deal, but it would make it easier to review quickly.

include/llvm/IR/InstIterator.h

130 ↗

(On Diff #18464)

I might call this inst_range. I'm usually not a fan of extra verbosity, but I see potential confusion resulting from a such short relatively common name being added to the llvm namespace.

lib/Analysis/MemDepPrinter.cpp

147 ↗

(On Diff #18464)

Please separate this refactoring into a separate change.

lib/Analysis/MemDerefPrinter.cpp

1 ↗

(On Diff #18464)

Please split the introduction of the printer and one or two example tests into it's own change. I'll be happy to LGTM that one quickly.

22 ↗

(On Diff #18464)

Why do you need to capture F?

24 ↗

(On Diff #18464)

Why is this enum needed?

43 ↗

(On Diff #18464)

You should also clear your small vector. (I think)

lib/IR/Value.cpp

575 ↗

(On Diff #18464)

I'd suggest using isGCRelocate here.

[artagnon]

Split print-memderefs into its own change. Fix all-round sloppiness.

[reames]

LGTM.

For future reference, I read your comment "Split print-memderefs into its own change." as meaning that you'd split the MemDerefPrinter into a separate review thread. Since the original semantic change (which I thought was this thread) was blocked on that, I deleted the email without looking further.

lib/Analysis/MemDerefPrinter.cpp

48 ↗

(On Diff #18843)

It would be better to get the data layout if available and use it here. You'll get far more precise results.

(This can be separate change if desired.)

llvm/trunk/include/llvm/Analysis/Passes.h

namespace llvm {
   // createMemDepPrinter - This pass exhaustively collects all memdep
   // information and prints it with -analyze.
   //
   FunctionPass *createMemDepPrinter();
 
   // createJumpInstrTableInfoPass - This creates a pass that stores information
   // about the jump tables created by JumpInstrTables
   ImmutablePass *createJumpInstrTableInfoPass();
+
+  //===--------------------------------------------------------------------===//
+  //
+  // createMemDerefPrinter - This pass collects memory dereferenceability
+  // information and prints it with -analyze.
+  //
+  FunctionPass *createMemDerefPrinter();
+
 }
 
 #endif

llvm/trunk/include/llvm/IR/InstIterator.h

typedef InstIterator<iplist<BasicBlock>,
                      Instruction> inst_iterator;
 typedef InstIterator<const iplist<BasicBlock>,
                      Function::const_iterator,
                      BasicBlock::const_iterator,
                      const Instruction> const_inst_iterator;
 
 inline inst_iterator inst_begin(Function *F) { return inst_iterator(*F); }
 inline inst_iterator inst_end(Function *F)   { return inst_iterator(*F, true); }
+inline iterator_range<inst_iterator> inst_range(Function *F) {
+  return iterator_range<inst_iterator>(inst_begin(F), inst_end(F));
+}
 inline const_inst_iterator inst_begin(const Function *F) {
   return const_inst_iterator(*F);
 }
 inline const_inst_iterator inst_end(const Function *F) {
   return const_inst_iterator(*F, true);
 }
+inline iterator_range<const_inst_iterator> inst_range(const Function *F) {
+  return iterator_range<const_inst_iterator>(inst_begin(F), inst_end(F));
+}
 inline inst_iterator inst_begin(Function &F) { return inst_iterator(F); }
 inline inst_iterator inst_end(Function &F)   { return inst_iterator(F, true); }
+inline iterator_range<inst_iterator> inst_range(Function &F) {
+  return iterator_range<inst_iterator>(inst_begin(F), inst_end(F));
+}
 inline const_inst_iterator inst_begin(const Function &F) {
   return const_inst_iterator(F);
 }
 inline const_inst_iterator inst_end(const Function &F) {
   return const_inst_iterator(F, true);
 }
+inline iterator_range<const_inst_iterator> inst_range(const Function &F) {
+  return iterator_range<const_inst_iterator>(inst_begin(F), inst_end(F));
+}
 
 } // End llvm namespace
 
 #endif

llvm/trunk/include/llvm/InitializePasses.h

 void initializeMachineModuleInfoPass(PassRegistry&);
 void initializeMachineRegionInfoPassPass(PassRegistry&);
 void initializeMachineSchedulerPass(PassRegistry&);
 void initializeMachineSinkingPass(PassRegistry&);
 void initializeMachineTraceMetricsPass(PassRegistry&);
 void initializeMachineVerifierPassPass(PassRegistry&);
 void initializeMemCpyOptPass(PassRegistry&);
 void initializeMemDepPrinterPass(PassRegistry&);
+void initializeMemDerefPrinterPass(PassRegistry&);
 void initializeMemoryDependenceAnalysisPass(PassRegistry&);
 void initializeMergedLoadStoreMotionPass(PassRegistry &);
 void initializeMetaRenamerPass(PassRegistry&);
 void initializeMergeFunctionsPass(PassRegistry&);
 void initializeModuleDebugInfoPrinterPass(PassRegistry&);
 void initializeNoAAPass(PassRegistry&);
 void initializeObjCARCAliasAnalysisPass(PassRegistry&);
 void initializeObjCARCAPElimPass(PassRegistry&);

llvm/trunk/include/llvm/LinkAllPasses.h

ForcePassLinking() {
       (void) llvm::createLoopVectorizePass();
       (void) llvm::createSLPVectorizerPass();
       (void) llvm::createBBVectorizePass();
       (void) llvm::createPartiallyInlineLibCallsPass();
       (void) llvm::createScalarizerPass();
       (void) llvm::createSeparateConstOffsetFromGEPPass();
       (void) llvm::createRewriteSymbolsPass();
       (void) llvm::createStraightLineStrengthReducePass();
+      (void) llvm::createMemDerefPrinter();
 
       (void)new llvm::IntervalPartition();
       (void)new llvm::ScalarEvolution();
       ((llvm::Function*)nullptr)->viewCFGOnly();
       llvm::RGPassManager RGM;
       ((llvm::RegionPass*)nullptr)->runOnRegion((llvm::Region*)nullptr, RGM);
       llvm::AliasSetTracker X(*(llvm::AliasAnalysis*)nullptr);
       X.add(nullptr, 0, llvm::AAMDNodes()); // for -print-alias-sets
     }
   } ForcePassLinking; // Force link by creating a global definition.
 }
 
 #endif

llvm/trunk/lib/Analysis/Analysis.cpp

void llvm::initializeAnalysis(PassRegistry &Registry) {
   initializeInstCountPass(Registry);
   initializeIntervalPartitionPass(Registry);
   initializeJumpInstrTableInfoPass(Registry);
   initializeLazyValueInfoPass(Registry);
   initializeLibCallAliasAnalysisPass(Registry);
   initializeLintPass(Registry);
   initializeLoopInfoWrapperPassPass(Registry);
   initializeMemDepPrinterPass(Registry);
+  initializeMemDerefPrinterPass(Registry);
   initializeMemoryDependenceAnalysisPass(Registry);
   initializeModuleDebugInfoPrinterPass(Registry);
   initializePostDominatorTreePass(Registry);
   initializeRegionInfoPassPass(Registry);
   initializeRegionViewerPass(Registry);
   initializeRegionPrinterPass(Registry);
   initializeRegionOnlyViewerPass(Registry);
   initializeRegionOnlyPrinterPass(Registry);

llvm/trunk/lib/Analysis/CMakeLists.txt

add_llvm_library(LLVMAnalysis
   LibCallAliasAnalysis.cpp
   LibCallSemantics.cpp
   Lint.cpp
   Loads.cpp
   LoopAccessAnalysis.cpp
   LoopInfo.cpp
   LoopPass.cpp
   MemDepPrinter.cpp
+  MemDerefPrinter.cpp
   MemoryBuiltins.cpp
   MemoryDependenceAnalysis.cpp
   ModuleDebugInfoPrinter.cpp
   NoAliasAnalysis.cpp
   PHITransAddr.cpp
   PostDominators.cpp
   PtrUseVisitor.cpp
   RegionInfo.cpp

llvm/trunk/lib/Analysis/MemDerefPrinter.cpp

+//===- MemDerefPrinter.cpp - Printer for isDereferenceablePointer ---------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Analysis/Passes.h"
+#include "llvm/ADT/SetVector.h"
+#include "llvm/Analysis/MemoryDependenceAnalysis.h"
+#include "llvm/IR/CallSite.h"
+#include "llvm/IR/InstIterator.h"
+#include "llvm/IR/LLVMContext.h"
+#include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/raw_ostream.h"
+using namespace llvm;
+
+namespace {
+  struct MemDerefPrinter : public FunctionPass {
+    SmallVector<Value *, 4> Vec;
+
+    static char ID; // Pass identifcation, replacement for typeid
+    MemDerefPrinter() : FunctionPass(ID) {
+      initializeMemDerefPrinterPass(*PassRegistry::getPassRegistry());
+    }
+    bool runOnFunction(Function &F) override;
+    void print(raw_ostream &OS, const Module * = nullptr) const override;
+    void releaseMemory() override {
+      Vec.clear();
+    }
+  };
+}
+
+char MemDerefPrinter::ID = 0;
+INITIALIZE_PASS(MemDerefPrinter, "print-memderefs",
+                "Memory Dereferenciblity of pointers in function", false, true)
+
+FunctionPass *llvm::createMemDerefPrinter() {
+  return new MemDerefPrinter();
+}
+
+bool MemDerefPrinter::runOnFunction(Function &F) {
+  for (auto &I: inst_range(F)) {
+    if (LoadInst *LI = dyn_cast<LoadInst>(&I)) {
+      Value *PO = LI->getPointerOperand();
+      if (PO->isDereferenceablePointer(nullptr))
+        Vec.push_back(PO);
+    }
+  }
+  return false;
+}
+
+void MemDerefPrinter::print(raw_ostream &OS, const Module *M) const {
+  OS << "The following are dereferenceable:\n";
+  for (auto &V: Vec) {
+    V->print(OS);
+    OS << "\n\n";
+  }
+}

llvm/trunk/test/Analysis/ValueTracking/memory-dereferenceable.ll

+; RUN: opt -print-memderefs -analyze -S <%s | FileCheck %s
+
+; Uses the print-deref (+ analyze to print) pass to run
+; isDereferenceablePointer() on many load instruction operands
+
+declare zeroext i1 @return_i1()
+
+@globalstr = global [6 x i8] c"hello\00"
+
+define void @test(i32 addrspace(1)* byval %dparam) {
+; CHECK: The following are dereferenceable:
+; CHECK: %globalptr
+; CHECK: %alloca
+; CHECK: %dparam
+; We haven't yet taught it to look through relocations
+; CHECK-NOT: %relocate
+; CHECK-NOT: %nparam
+entry:
+    %globalptr = getelementptr inbounds [6 x i8]* @globalstr, i32 0, i32 0
+    %load1 = load i8* %globalptr
+    %alloca = alloca i1
+    %load2 = load i1* %alloca
+    %load3 = load i32 addrspace(1)* %dparam
+    %tok = tail call i32 (i1 ()*, i32, i32, ...)* @llvm.experimental.gc.statepoint.p0f_i1f(i1 ()* @return_i1, i32 0, i32 0, i32 0, i32 addrspace(1)* %dparam)
+    %relocate = call i32 addrspace(1)* @llvm.experimental.gc.relocate.p1i32(i32 %tok, i32 4, i32 4)
+    %load4 = load i32 addrspace(1)* %relocate
+    %nparam = getelementptr i32 addrspace(1)* %dparam, i32 5
+    %load5 = load i32 addrspace(1)* %nparam
+    ret void
+}
+
+declare i32 @llvm.experimental.gc.statepoint.p0f_i1f(i1 ()*, i32, i32, ...)
+declare i32 addrspace(1)* @llvm.experimental.gc.relocate.p1i32(i32, i32, i32)