diff --git a/lib/Transforms/Scalar/ScalarReplAggregates.cpp b/lib/Transforms/Scalar/ScalarReplAggregates.cpp index 6f4f17e20fb..fe40bcc22d5 100644 --- a/lib/Transforms/Scalar/ScalarReplAggregates.cpp +++ b/lib/Transforms/Scalar/ScalarReplAggregates.cpp @@ -34,6 +34,7 @@ #include "llvm/Target/TargetData.h" #include "llvm/Transforms/Utils/PromoteMemToReg.h" #include "llvm/Transforms/Utils/Local.h" +#include "llvm/Support/CallSite.h" #include "llvm/Support/Debug.h" #include "llvm/Support/ErrorHandling.h" #include "llvm/Support/GetElementPtrTypeIterator.h" @@ -1810,6 +1811,12 @@ static bool isOnlyCopiedFromConstantGlobal(Value *V, MemTransferInst *&TheCopy, continue; } + // If this is a readonly/readnone call site, then we know it is just a load + // and we can ignore it. + if (CallSite CS = U) + if (CS.onlyReadsMemory()) + continue; + // If this is isn't our memcpy/memmove, reject it as something we can't // handle. MemTransferInst *MI = dyn_cast(U); diff --git a/test/Transforms/ScalarRepl/memcpy-from-global.ll b/test/Transforms/ScalarRepl/memcpy-from-global.ll index e807177357b..68fc2a2c581 100644 --- a/test/Transforms/ScalarRepl/memcpy-from-global.ll +++ b/test/Transforms/ScalarRepl/memcpy-from-global.ll @@ -68,3 +68,16 @@ define void @test2() { } declare void @bar(i8*) + + +;; Should be able to eliminate the alloca. +define void @test3() { + %A = alloca %T + %a = bitcast %T* %A to i8* + call void @llvm.memcpy.p0i8.p0i8.i64(i8* %a, i8* bitcast (%T* @G to i8*), i64 124, i32 4, i1 false) + call void @bar(i8* %a) readonly +; CHECK: @test3 +; CHECK-NEXT: %a = bitcast %T* @G to i8* +; CHECK-NEXT: call void @bar(i8* %a) + ret void +}