From 745291a6ce841f30a8a9e536071bd1b4cf540c55 Mon Sep 17 00:00:00 2001 From: Chris Lattner Date: Sun, 7 Dec 2008 00:28:02 +0000 Subject: [PATCH] a memdep query on a volatile load/store will always return clobber with the current implementation. Instead of returning a "precise clobber" just return a fuzzy one. This doesn't matter to any clients anyway and should speed up analysis time very very slightly. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@60641 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Analysis/MemoryDependenceAnalysis.cpp | 21 ++++++++++----------- 1 file changed, 10 insertions(+), 11 deletions(-) diff --git a/lib/Analysis/MemoryDependenceAnalysis.cpp b/lib/Analysis/MemoryDependenceAnalysis.cpp index 24e45520c25..cf748dfd89c 100644 --- a/lib/Analysis/MemoryDependenceAnalysis.cpp +++ b/lib/Analysis/MemoryDependenceAnalysis.cpp @@ -116,16 +116,23 @@ getDependencyFrom(Instruction *QueryInst, BasicBlock::iterator ScanIt, // Get the pointer value for which dependence will be determined Value *MemPtr = 0; uint64_t MemSize = 0; - bool MemVolatile = false; if (StoreInst* S = dyn_cast(QueryInst)) { + // If this is a volatile store, don't mess around with it. Just return the + // previous instruction as a clobber. + if (S->isVolatile()) + return MemDepResult::getClobber(--ScanIt); + MemPtr = S->getPointerOperand(); MemSize = TD->getTypeStoreSize(S->getOperand(0)->getType()); - MemVolatile = S->isVolatile(); } else if (LoadInst* LI = dyn_cast(QueryInst)) { + // If this is a volatile load, don't mess around with it. Just return the + // previous instruction as a clobber. + if (S->isVolatile()) + return MemDepResult::getClobber(--ScanIt); + MemPtr = LI->getPointerOperand(); MemSize = TD->getTypeStoreSize(LI->getType()); - MemVolatile = LI->isVolatile(); } else if (FreeInst* F = dyn_cast(QueryInst)) { MemPtr = F->getPointerOperand(); // FreeInsts erase the entire structure, not just a field. @@ -145,10 +152,6 @@ getDependencyFrom(Instruction *QueryInst, BasicBlock::iterator ScanIt, // Values depend on loads if the pointers are must aliased. This means that // a load depends on another must aliased load from the same value. if (LoadInst *LI = dyn_cast(Inst)) { - // If the access is volatile and this is volatile, return a dependence. - if (MemVolatile && LI->isVolatile()) - return MemDepResult::getClobber(LI); - Value *Pointer = LI->getPointerOperand(); uint64_t PointerSize = TD->getTypeStoreSize(LI->getType()); @@ -165,10 +168,6 @@ getDependencyFrom(Instruction *QueryInst, BasicBlock::iterator ScanIt, } if (StoreInst *SI = dyn_cast(Inst)) { - // If the access is volatile and this is volatile, return a dependence. - if (MemVolatile && SI->isVolatile()) - return MemDepResult::getClobber(SI); - Value *Pointer = SI->getPointerOperand(); uint64_t PointerSize = TD->getTypeStoreSize(SI->getOperand(0)->getType()); -- 2.11.0