From 8da0b7358d30b8a91648bd30046137376bf85464 Mon Sep 17 00:00:00 2001 From: Benjamin Kramer Date: Mon, 10 Mar 2014 21:05:13 +0000 Subject: [PATCH] MemCpyOpt: When merging memsets also merge the trivial case of two memsets with the same destination. The testcase is from PR19092, but I think the bug described there is actually a clang issue. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@203489 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Transforms/Scalar/MemCpyOptimizer.cpp | 7 +++++++ test/Transforms/MemCpyOpt/form-memset.ll | 12 ++++++++++++ 2 files changed, 19 insertions(+) diff --git a/lib/Transforms/Scalar/MemCpyOptimizer.cpp b/lib/Transforms/Scalar/MemCpyOptimizer.cpp index 348e12f35b8..143ba38ec98 100644 --- a/lib/Transforms/Scalar/MemCpyOptimizer.cpp +++ b/lib/Transforms/Scalar/MemCpyOptimizer.cpp @@ -75,6 +75,13 @@ static bool IsPointerOffset(Value *Ptr1, Value *Ptr2, int64_t &Offset, const DataLayout &TD) { Ptr1 = Ptr1->stripPointerCasts(); Ptr2 = Ptr2->stripPointerCasts(); + + // Handle the trivial case first. + if (Ptr1 == Ptr2) { + Offset = 0; + return true; + } + GEPOperator *GEP1 = dyn_cast(Ptr1); GEPOperator *GEP2 = dyn_cast(Ptr2); diff --git a/test/Transforms/MemCpyOpt/form-memset.ll b/test/Transforms/MemCpyOpt/form-memset.ll index 7c7b4fc0880..d980b7fdbd6 100644 --- a/test/Transforms/MemCpyOpt/form-memset.ll +++ b/test/Transforms/MemCpyOpt/form-memset.ll @@ -272,3 +272,15 @@ define void @test9() nounwind { ; CHECK-LABEL: @test9( ; CHECK: call void @llvm.memset.p0i8.i64(i8* bitcast ([16 x i64]* @test9buf to i8*), i8 -1, i64 16, i32 16, i1 false) } + +; PR19092 +define void @test10(i8* nocapture %P) nounwind { + tail call void @llvm.memset.p0i8.i64(i8* %P, i8 0, i64 42, i32 1, i1 false) + tail call void @llvm.memset.p0i8.i64(i8* %P, i8 0, i64 23, i32 1, i1 false) + ret void +; CHECK-LABEL: @test10( +; CHECK-NOT: memset +; CHECK: call void @llvm.memset.p0i8.i64(i8* %P, i8 0, i64 42, i32 1, i1 false) +; CHECK-NOT: memset +; CHECK: ret void +}