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| author | Chris Lattner <sabre@nondot.org> | 2008-05-08 17:20:30 +0000 |
|---|---|---|
| committer | Chris Lattner <sabre@nondot.org> | 2008-05-08 17:20:30 +0000 |
| commit | 0ef546e639d45207b4776c80408c84170ad1cac6 (patch) | |
| tree | 3abf3f2ff98b2ab223f4464caced8eba2c461d7c | |
| parent | d96288a2ff188bb1fb1b86fb89b1ac82f6310a5c (diff) | |
| download | external_llvm-0ef546e639d45207b4776c80408c84170ad1cac6.zip external_llvm-0ef546e639d45207b4776c80408c84170ad1cac6.tar.gz external_llvm-0ef546e639d45207b4776c80408c84170ad1cac6.tar.bz2 | |
Make instcombine's DSE respect loads as well as stores. It is not safe to
delete the first store in:
store x -> p
load p
store y -> p
This is for PR2297.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@50859 91177308-0d34-0410-b5e6-96231b3b80d8
| -rw-r--r-- | lib/Transforms/Scalar/InstructionCombining.cpp | 2 | ||||
| -rw-r--r-- | test/Transforms/InstCombine/2008-05-08-LiveStoreDelete.ll | 25 |
2 files changed, 26 insertions, 1 deletions
diff --git a/lib/Transforms/Scalar/InstructionCombining.cpp b/lib/Transforms/Scalar/InstructionCombining.cpp index a3340a0..b0ea9f5 100644 --- a/lib/Transforms/Scalar/InstructionCombining.cpp +++ b/lib/Transforms/Scalar/InstructionCombining.cpp @@ -10426,7 +10426,7 @@ Instruction *InstCombiner::visitStoreInst(StoreInst &SI) { } // Don't skip over loads or things that can modify memory. - if (BBI->mayWriteToMemory()) + if (BBI->mayWriteToMemory() || BBI->mayReadFromMemory()) break; } diff --git a/test/Transforms/InstCombine/2008-05-08-LiveStoreDelete.ll b/test/Transforms/InstCombine/2008-05-08-LiveStoreDelete.ll new file mode 100644 index 0000000..e9cc97d --- /dev/null +++ b/test/Transforms/InstCombine/2008-05-08-LiveStoreDelete.ll @@ -0,0 +1,25 @@ +; RUN: llvm-as < %s | opt -instcombine | llvm-dis | grep {store i8} | count 3 +; 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] + ret i32 %tmp7 +} + +declare i8* @malloc(i32) nounwind + +declare i32 @strlen(i8*) nounwind readonly + +declare i32 @b(...) |