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Another load-peephole optimization: do gcse when two loads are next to

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each other.  This implements InstCombine/load.ll:test9


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@23322 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner
2005-09-12 22:21:03 +00:00
parent 128a0032a2
commit 9c1f0fd8de
1 changed files with 5 additions and 2 deletions
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7
lib/Transforms/Scalar/InstructionCombining.cpp
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@@ -4926,13 +4926,16 @@ Instruction *InstCombiner::visitLoadInst(LoadInst &LI) {
// None of the following transforms are legal for volatile loads. // None of the following transforms are legal for volatile loads.
if (LI.isVolatile()) return 0; if (LI.isVolatile()) return 0;
// If the instruction immediately before this is a store to the same address,
// do a simple form of store->load forwarding.
if (&LI.getParent()->front() != &LI) { if (&LI.getParent()->front() != &LI) {
BasicBlock::iterator BBI = &LI; --BBI; BasicBlock::iterator BBI = &LI; --BBI;
// If the instruction immediately before this is a store to the same
// address, do a simple form of store->load forwarding.
if (StoreInst *SI = dyn_cast<StoreInst>(BBI)) if (StoreInst *SI = dyn_cast<StoreInst>(BBI))
if (SI->getOperand(1) == LI.getOperand(0)) if (SI->getOperand(1) == LI.getOperand(0))
return ReplaceInstUsesWith(LI, SI->getOperand(0)); return ReplaceInstUsesWith(LI, SI->getOperand(0));
if (LoadInst *LIB = dyn_cast<LoadInst>(BBI))
if (LIB->getOperand(0) == LI.getOperand(0))
return ReplaceInstUsesWith(LI, LIB);
} }
if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(Op)) if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(Op))