From 2539e3389361115f5e75e4134bdd123171688ddc Mon Sep 17 00:00:00 2001
From: Chris Lattner <sabre@nondot.org>
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.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@50860 91177308-0d34-0410-b5e6-96231b3b80d8
---
.../Scalar/InstructionCombining.cpp | 8 +++---
.../InstCombine/2008-05-08-StrLenSink.ll | 28 +++++++++++++++++++
2 files changed, 32 insertions(+), 4 deletions(-)
create mode 100644 test/Transforms/InstCombine/2008-05-08-StrLenSink.ll
diff --git a/lib/Transforms/Scalar/InstructionCombining.cpp b/lib/Transforms/Scalar/InstructionCombining.cpp
index b0ea9f5c43f..772ef63121b 100644
--- a/lib/Transforms/Scalar/InstructionCombining.cpp
+++ b/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<LoadInst>(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<GetResultInst>(I)) {
BasicBlock *BB = I->getParent();
BasicBlock *UserParent = cast<Instruction>(I->use_back())->getParent();
diff --git a/test/Transforms/InstCombine/2008-05-08-StrLenSink.ll b/test/Transforms/InstCombine/2008-05-08-StrLenSink.ll
new file mode 100644
index 00000000000..e81e828d51f
--- /dev/null
+++ b/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 ; <i32> [#uses=0]
+ %tmp1 = call i8* @malloc( i32 10 ) nounwind ; <i8*> [#uses=5]
+ %tmp3 = getelementptr i8* %tmp1, i32 1 ; <i8*> [#uses=1]
+ store i8 0, i8* %tmp3, align 1
+ %tmp5 = getelementptr i8* %tmp1, i32 0 ; <i8*> [#uses=1]
+ store i8 1, i8* %tmp5, align 1
+ %tmp7 = call i32 @strlen( i8* %tmp1 ) nounwind readonly ; <i32> [#uses=1]
+ %tmp9 = getelementptr i8* %tmp1, i32 0 ; <i8*> [#uses=1]
+ store i8 0, i8* %tmp9, align 1
+ %tmp11 = call i32 (...)* @b( i8* %tmp1 ) nounwind ; <i32> [#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(...)