From 49a594e6abe6e902cc6e5bc61322b56bf7c3a0ba Mon Sep 17 00:00:00 2001 From: Chris Lattner Date: Thu, 8 May 2008 17:37:37 +0000 Subject: [PATCH] More than just loads can read from memory: readonly calls like strlen also need to be checked for memory modifying instructions before we can sink them. THis fixes the second half of PR2297. llvm-svn: 50860 --- .../Scalar/InstructionCombining.cpp | 8 +++--- .../InstCombine/2008-05-08-StrLenSink.ll | 28 +++++++++++++++++++ 2 files changed, 32 insertions(+), 4 deletions(-) create mode 100644 llvm/test/Transforms/InstCombine/2008-05-08-StrLenSink.ll diff --git a/llvm/lib/Transforms/Scalar/InstructionCombining.cpp b/llvm/lib/Transforms/Scalar/InstructionCombining.cpp index b0ea9f5c43fd..772ef63121b0 100644 --- a/llvm/lib/Transforms/Scalar/InstructionCombining.cpp +++ b/llvm/lib/Transforms/Scalar/InstructionCombining.cpp @@ -11229,8 +11229,8 @@ static bool TryToSinkInstruction(Instruction *I, BasicBlock *DestBlock) { // We can only sink load instructions if there is nothing between the load and // the end of block that could change the value. - if (LoadInst *LI = dyn_cast(I)) { - for (BasicBlock::iterator Scan = LI, E = LI->getParent()->end(); + if (I->mayReadFromMemory()) { + for (BasicBlock::iterator Scan = I, E = I->getParent()->end(); Scan != E; ++Scan) if (Scan->mayWriteToMemory()) return false; @@ -11388,8 +11388,8 @@ bool InstCombiner::DoOneIteration(Function &F, unsigned Iteration) { } // See if we can trivially sink this instruction to a successor basic block. - // FIXME: Remove GetResultInst test when first class support for aggregates is - // implemented. + // FIXME: Remove GetResultInst test when first class support for aggregates + // is implemented. if (I->hasOneUse() && !isa(I)) { BasicBlock *BB = I->getParent(); BasicBlock *UserParent = cast(I->use_back())->getParent(); diff --git a/llvm/test/Transforms/InstCombine/2008-05-08-StrLenSink.ll b/llvm/test/Transforms/InstCombine/2008-05-08-StrLenSink.ll new file mode 100644 index 000000000000..e81e828d51f3 --- /dev/null +++ b/llvm/test/Transforms/InstCombine/2008-05-08-StrLenSink.ll @@ -0,0 +1,28 @@ +; RUN: llvm-as < %s | opt -instcombine | llvm-dis | %prcontext strlen 1 | not grep ret +; PR2297 +target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:128:128" +target triple = "i386-apple-darwin8" + +define i32 @a() nounwind { +entry: + %"alloca point" = bitcast i32 0 to i32 ; [#uses=0] + %tmp1 = call i8* @malloc( i32 10 ) nounwind ; [#uses=5] + %tmp3 = getelementptr i8* %tmp1, i32 1 ; [#uses=1] + store i8 0, i8* %tmp3, align 1 + %tmp5 = getelementptr i8* %tmp1, i32 0 ; [#uses=1] + store i8 1, i8* %tmp5, align 1 + %tmp7 = call i32 @strlen( i8* %tmp1 ) nounwind readonly ; [#uses=1] + %tmp9 = getelementptr i8* %tmp1, i32 0 ; [#uses=1] + store i8 0, i8* %tmp9, align 1 + %tmp11 = call i32 (...)* @b( i8* %tmp1 ) nounwind ; [#uses=0] + br label %return + +return: ; preds = %entry + ret i32 %tmp7 +} + +declare i8* @malloc(i32) nounwind + +declare i32 @strlen(i8*) nounwind readonly + +declare i32 @b(...)