From b4db97ffa7a153f2301074652aeb5faf28849eaf Mon Sep 17 00:00:00 2001 From: Chris Lattner Date: Fri, 26 May 2006 19:19:20 +0000 Subject: [PATCH] Implement Transforms/InstCombine/store.ll:test2. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@28503 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Transforms/Scalar/InstructionCombining.cpp | 16 +++++++++++++++- 1 file changed, 15 insertions(+), 1 deletion(-) diff --git a/lib/Transforms/Scalar/InstructionCombining.cpp b/lib/Transforms/Scalar/InstructionCombining.cpp index 1264e55497d..30a1de23aa4 100644 --- a/lib/Transforms/Scalar/InstructionCombining.cpp +++ b/lib/Transforms/Scalar/InstructionCombining.cpp @@ -6833,8 +6833,22 @@ Instruction *InstCombiner::visitStoreInst(StoreInst &SI) { break; } + // If this is a load, we have to stop. However, if the loaded value is from + // the pointer we're loading and is producing the pointer we're storing, + // then *this* store is dead (X = load P; store X -> P). + if (LoadInst *LI = dyn_cast(BBI)) { + if (LI == Val && LI->getOperand(0) == Ptr) { + EraseInstFromFunction(SI); + ++NumCombined; + return 0; + } + // Otherwise, this is a load from some other location. Stores before it + // may not be dead. + break; + } + // Don't skip over loads or things that can modify memory. - if (BBI->mayWriteToMemory() || isa(BBI)) + if (BBI->mayWriteToMemory()) break; }