From 37508bb842d9beedd75139a589c6f538f90efbaa Mon Sep 17 00:00:00 2001 From: Chandler Carruth Date: Sun, 11 Aug 2013 01:56:15 +0000 Subject: Finish fixing the SSAUpdater-based AllocaPromoter strategy in SROA to cope with the more general set of patterns that are now handled by mem2reg and that we can detect quickly while doing SROA's initial analysis. Notably, this allows it to promote through no-op bitcast and GEP sequences. A core part of the SSAUpdater approach is the ability to test whether a particular instruction is part of the set being promoted. Testing this becomes significantly more complex in the world where the operand to every load and store isn't the alloca itself. I ended up using the approach of walking up the def-chain until we find the alloca. I benchmarked this against keeping a set of pointer operands and keeping a set of the loads and stores we care about, and this one seemed faster although the difference was very small. No test case yet because currently the rewriting always "fixes" the inputs to not require this. The next patch which re-enables early promotion of easy cases in SROA will include a test case that specifically exercises this aspect of the alloca promoter. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@188145 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Transforms/Scalar/SROA.cpp | 25 +++++++++++++++++++++++-- 1 file changed, 23 insertions(+), 2 deletions(-) (limited to 'lib/Transforms/Scalar/SROA.cpp') diff --git a/lib/Transforms/Scalar/SROA.cpp b/lib/Transforms/Scalar/SROA.cpp index 2793825137..d35c3b5e83 100644 --- a/lib/Transforms/Scalar/SROA.cpp +++ b/lib/Transforms/Scalar/SROA.cpp @@ -762,9 +762,30 @@ public: virtual bool isInstInList(Instruction *I, const SmallVectorImpl &Insts) const { + Value *Ptr; if (LoadInst *LI = dyn_cast(I)) - return LI->getOperand(0) == &AI; - return cast(I)->getPointerOperand() == &AI; + Ptr = LI->getOperand(0); + else + Ptr = cast(I)->getPointerOperand(); + + // Only used to detect cycles, which will be rare and quickly found as + // we're walking up a chain of defs rather than down through uses. + SmallPtrSet Visited; + + do { + if (Ptr == &AI) + return true; + + if (BitCastInst *BCI = dyn_cast(Ptr)) + Ptr = BCI->getOperand(0); + else if (GetElementPtrInst *GEPI = dyn_cast(Ptr)) + Ptr = GEPI->getPointerOperand(); + else + return false; + + } while (Visited.insert(Ptr)); + + return false; } virtual void updateDebugInfo(Instruction *Inst) const { -- cgit v1.2.3