diff --git a/llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp b/llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp --- a/llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp +++ b/llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp @@ -56,6 +56,7 @@ #include "llvm/IR/DataLayout.h" #include "llvm/IR/Dominators.h" #include "llvm/IR/Function.h" +#include "llvm/IR/IRBuilder.h" #include "llvm/IR/InstIterator.h" #include "llvm/IR/InstrTypes.h" #include "llvm/IR/Instruction.h" @@ -78,6 +79,7 @@ #include "llvm/Support/raw_ostream.h" #include "llvm/Transforms/Scalar.h" #include "llvm/Transforms/Utils/AssumeBundleBuilder.h" +#include "llvm/Transforms/Utils/BuildLibCalls.h" #include "llvm/Transforms/Utils/Local.h" #include #include @@ -505,7 +507,12 @@ BasicBlock::iterator SecondBBI(SecondI); BasicBlock *FirstBB = FirstI->getParent(); BasicBlock *SecondBB = SecondI->getParent(); - MemoryLocation MemLoc = MemoryLocation::get(SecondI); + MemoryLocation MemLoc; + if (auto *MemSet = dyn_cast(SecondI)) + MemLoc = MemoryLocation::getForDest(MemSet); + else + MemLoc = MemoryLocation::get(SecondI); + auto *MemLocPtr = const_cast(MemLoc.Ptr); // Start checking the SecondBB. @@ -819,14 +826,17 @@ } // Check if we can ignore \p D for DSE. -bool canSkipDef(MemoryDef *D, bool DefVisibleToCaller) { +bool canSkipDef(MemoryDef *D, bool DefVisibleToCaller, + const TargetLibraryInfo &TLI) { Instruction *DI = D->getMemoryInst(); // Calls that only access inaccessible memory cannot read or write any memory // locations we consider for elimination. if (auto *CB = dyn_cast(DI)) - if (CB->onlyAccessesInaccessibleMemory()) + if (CB->onlyAccessesInaccessibleMemory()) { + if (isAllocLikeFn(DI, &TLI)) + return false; return true; - + } // We can eliminate stores to locations not visible to the caller across // throwing instructions. if (DI->mayThrow() && !DefVisibleToCaller) @@ -841,7 +851,7 @@ return true; // Skip intrinsics that do not really read or modify memory. - if (isNoopIntrinsic(D->getMemoryInst())) + if (isNoopIntrinsic(DI)) return true; return false; @@ -1389,7 +1399,7 @@ MemoryDef *CurrentDef = cast(Current); Instruction *CurrentI = CurrentDef->getMemoryInst(); - if (canSkipDef(CurrentDef, !isInvisibleToCallerBeforeRet(DefUO))) + if (canSkipDef(CurrentDef, !isInvisibleToCallerBeforeRet(DefUO), TLI)) continue; // Before we try to remove anything, check for any extra throwing @@ -1816,13 +1826,55 @@ if (StoredConstant && StoredConstant->isNullValue()) { auto *DefUOInst = dyn_cast(DefUO); - if (DefUOInst && isCallocLikeFn(DefUOInst, &TLI)) { - auto *UnderlyingDef = cast(MSSA.getMemoryAccess(DefUOInst)); - // If UnderlyingDef is the clobbering access of Def, no instructions - // between them can modify the memory location. - auto *ClobberDef = - MSSA.getSkipSelfWalker()->getClobberingMemoryAccess(Def); - return UnderlyingDef == ClobberDef; + if (DefUOInst) { + if (isCallocLikeFn(DefUOInst, &TLI)) { + auto *UnderlyingDef = + cast(MSSA.getMemoryAccess(DefUOInst)); + // If UnderlyingDef is the clobbering access of Def, no instructions + // between them can modify the memory location. + auto *ClobberDef = + MSSA.getSkipSelfWalker()->getClobberingMemoryAccess(Def); + return UnderlyingDef == ClobberDef; + } + + if (MemSet) { + if (F.hasFnAttribute(Attribute::SanitizeMemory)) + return false; + auto *Malloc = const_cast(dyn_cast(DefUOInst)); + if (!Malloc) + return false; + auto *InnerCallee = Malloc->getCalledFunction(); + if (!InnerCallee) + return false; + LibFunc Func; + if (!TLI.getLibFunc(*InnerCallee, Func) || !TLI.has(Func) || + Func != LibFunc_malloc) + return false; + if (Malloc->getOperand(0) == MemSet->getLength()) { + if (DT.dominates(Malloc, MemSet) && + memoryIsNotModifiedBetween(Malloc, MemSet, BatchAA, DL, &DT)) { + IRBuilder<> IRB(Malloc); + const auto &DL = Malloc->getModule()->getDataLayout(); + AttributeList EmptyList; + if (auto *Calloc = emitCalloc( + ConstantInt::get(IRB.getIntPtrTy(DL), 1), + Malloc->getArgOperand(0), EmptyList, IRB, TLI)) { + MemorySSAUpdater Updater(&MSSA); + auto *LastDef = cast( + Updater.getMemorySSA()->getMemoryAccess(Malloc)); + auto *NewAccess = Updater.createMemoryAccessAfter( + cast(Calloc), LastDef, LastDef); + auto *NewAccessMD = cast(NewAccess); + Updater.insertDef(NewAccessMD, /*RenameUses=*/true); + Updater.removeMemoryAccess(Malloc); + Malloc->replaceAllUsesWith(Calloc); + Malloc->eraseFromParent(); + return true; + } + return false; + } + } + } } } diff --git a/llvm/test/Transforms/DeadStoreElimination/noop-stores.ll b/llvm/test/Transforms/DeadStoreElimination/noop-stores.ll --- a/llvm/test/Transforms/DeadStoreElimination/noop-stores.ll +++ b/llvm/test/Transforms/DeadStoreElimination/noop-stores.ll @@ -1,6 +1,6 @@ ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py ; RUN: opt < %s -basic-aa -dse -S | FileCheck %s -; RUN: opt < %s -aa-pipeline=basic-aa -passes=dse -S | FileCheck %s +; RUN: opt < %s -aa-pipeline=basic-aa -passes='dse,verify' -S | FileCheck %s target datalayout = "E-p:64:64:64-a0:0:8-f32:32:32-f64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-v64:64:64-v128:128:128" declare i8* @calloc(i64, i64) @@ -309,6 +309,128 @@ ret void } +declare noalias i8* @malloc(i64) +declare noalias i8* @_Znwm(i64) +declare void @clobber_memory(float*) + +; based on pr25892_lite +define i8* @zero_memset_after_malloc(i64 %size) { +; CHECK-LABEL: @zero_memset_after_malloc( +; CHECK-NEXT: [[CALL:%.*]] = call i8* @calloc(i64 1, i64 [[SIZE:%.*]]) +; CHECK-NEXT: ret i8* [[CALL]] +; + %call = call i8* @malloc(i64 %size) inaccessiblememonly + call void @llvm.memset.p0i8.i64(i8* %call, i8 0, i64 %size, i1 false) + ret i8* %call +} + +; based on pr25892_lite +define i8* @zero_memset_after_malloc_with_intermediate_clobbering(i64 %size) { +; CHECK-LABEL: @zero_memset_after_malloc_with_intermediate_clobbering( +; CHECK-NEXT: [[CALL:%.*]] = call i8* @malloc(i64 [[SIZE:%.*]]) +; CHECK-NEXT: [[BC:%.*]] = bitcast i8* [[CALL]] to float* +; CHECK-NEXT: call void @clobber_memory(float* [[BC]]) +; CHECK-NEXT: call void @llvm.memset.p0i8.i64(i8* [[CALL]], i8 0, i64 [[SIZE]], i1 false) +; CHECK-NEXT: ret i8* [[CALL]] +; + %call = call i8* @malloc(i64 %size) inaccessiblememonly + %bc = bitcast i8* %call to float* + call void @clobber_memory(float* %bc) + call void @llvm.memset.p0i8.i64(i8* %call, i8 0, i64 %size, i1 false) + ret i8* %call +} + +; based on pr25892_lite +define i8* @zero_memset_after_malloc_with_different_sizes(i64 %size) { +; CHECK-LABEL: @zero_memset_after_malloc_with_different_sizes( +; CHECK-NEXT: [[CALL:%.*]] = call i8* @malloc(i64 [[SIZE:%.*]]) +; CHECK-NEXT: [[SIZE2:%.*]] = add nsw i64 [[SIZE]], -1 +; CHECK-NEXT: call void @llvm.memset.p0i8.i64(i8* [[CALL]], i8 0, i64 [[SIZE2]], i1 false) +; CHECK-NEXT: ret i8* [[CALL]] +; + %call = call i8* @malloc(i64 %size) inaccessiblememonly + %size2 = add nsw i64 %size, -1 + call void @llvm.memset.p0i8.i64(i8* %call, i8 0, i64 %size2, i1 false) + ret i8* %call +} + +; based on pr25892_lite +define i8* @zero_memset_after_new(i64 %size) { +; CHECK-LABEL: @zero_memset_after_new( +; CHECK-NEXT: [[CALL:%.*]] = call i8* @_Znwm(i64 [[SIZE:%.*]]) +; CHECK-NEXT: call void @llvm.memset.p0i8.i64(i8* [[CALL]], i8 0, i64 [[SIZE]], i1 false) +; CHECK-NEXT: ret i8* [[CALL]] +; + %call = call i8* @_Znwm(i64 %size) + call void @llvm.memset.p0i8.i64(i8* %call, i8 0, i64 %size, i1 false) + ret i8* %call +} + +; This should not create a calloc and should not crash the compiler. +define i8* @notmalloc_memset(i64 %size, i8*(i64)* %notmalloc) { +; CHECK-LABEL: @notmalloc_memset( +; CHECK-NEXT: [[CALL1:%.*]] = call i8* [[NOTMALLOC:%.*]](i64 [[SIZE:%.*]]) +; CHECK-NEXT: call void @llvm.memset.p0i8.i64(i8* [[CALL1]], i8 0, i64 [[SIZE]], i1 false) +; CHECK-NEXT: ret i8* [[CALL1]] +; + %call1 = call i8* %notmalloc(i64 %size) + call void @llvm.memset.p0i8.i64(i8* %call1, i8 0, i64 %size, i1 false) + ret i8* %call1 +} + +define float* @pr25892(i64 %size) { +; CHECK-LABEL: @pr25892( +; CHECK: entry: +; CHECK-NEXT: [[CALL:%.*]] = call i8* @calloc(i64 1, i64 [[SIZE:%.*]]) +; CHECK-NEXT: [[CMP:%.*]] = icmp eq i8* [[CALL]], null +; CHECK-NEXT: br i1 [[CMP]], label [[CLEANUP:%.*]], label [[IF_END:%.*]] +; CHECK: if.end: +; CHECK-NEXT: [[BC:%.*]] = bitcast i8* [[CALL]] to float* +; CHECK-NEXT: br label [[CLEANUP]] +; CHECK: cleanup: +; CHECK-NEXT: [[RETVAL_0:%.*]] = phi float* [ [[BC]], [[IF_END]] ], [ null, [[ENTRY:%.*]] ] +; CHECK-NEXT: ret float* [[RETVAL_0]] +; +entry: + %call = call i8* @malloc(i64 %size) inaccessiblememonly + %cmp = icmp eq i8* %call, null + br i1 %cmp, label %cleanup, label %if.end +if.end: + %bc = bitcast i8* %call to float* + call void @llvm.memset.p0i8.i64(i8* %call, i8 0, i64 %size, i1 false) + br label %cleanup +cleanup: + %retval.0 = phi float* [ %bc, %if.end ], [ null, %entry ] + ret float* %retval.0 +} + +; CHECK-LABEL: @pr25892_with_extra_store( +; CHECK: entry: +; CHECK-NEXT: [[CALL:%.*]] = call i8* @calloc(i64 1, i64 [[SIZE:%.*]]) +; CHECK-NEXT: [[CMP:%.*]] = icmp eq i8* [[CALL]], null +; CHECK-NEXT: br i1 [[CMP]], label [[CLEANUP:%.*]], label [[IF_END:%.*]] +; CHECK: if.end: +; CHECK-NEXT: [[BC:%.*]] = bitcast i8* [[CALL]] to float* +; CHECK-NEXT: br label [[CLEANUP]] +; CHECK: cleanup: +; CHECK-NEXT: [[RETVAL_0:%.*]] = phi float* [ [[BC]], [[IF_END]] ], [ null, [[ENTRY:%.*]] ] +; CHECK-NEXT: ret float* [[RETVAL_0]] +; +define float* @pr25892_with_extra_store(i64 %size) { +entry: + %call = call i8* @malloc(i64 %size) inaccessiblememonly + %cmp = icmp eq i8* %call, null + br i1 %cmp, label %cleanup, label %if.end +if.end: + %bc = bitcast i8* %call to float* + call void @llvm.memset.p0i8.i64(i8* %call, i8 0, i64 %size, i1 false) + store i8 0, i8* %call, align 1 + br label %cleanup +cleanup: + %retval.0 = phi float* [ %bc, %if.end ], [ null, %entry ] + ret float* %retval.0 +} + ; PR50143 define i8* @store_zero_after_calloc_inaccessiblememonly() { ; CHECK-LABEL: @store_zero_after_calloc_inaccessiblememonly(