From 1166f2ff9f30a84fea630888b297bf58c3dba7e9 Mon Sep 17 00:00:00 2001 From: Sanjay Patel Date: Thu, 30 Jul 2015 21:41:50 +0000 Subject: fix memcpy/memset/memmove lowering when optimizing for size Fixing MinSize attribute handling was discussed in D11363. This is a prerequisite patch to doing that. The handling of OptSize when lowering mem* functions was broken on Darwin because it wants to ignore -Os for these cases, but the existing logic also made it ignore -Oz (MinSize). The Linux change demonstrates a widespread problem. The backend doesn't usually recognize the MinSize attribute by itself; it assumes that if the MinSize attribute exists, then the OptSize attribute must also exist. Fixing this more generally will be a follow-on patch or two. Differential Revision: http://reviews.llvm.org/D11568 llvm-svn: 243693 --- llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp | 18 +++++++++++++++--- 1 file changed, 15 insertions(+), 3 deletions(-) (limited to 'llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp') diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp index d41d46b7b14..4122ce06b04 100644 --- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp +++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp @@ -4151,6 +4151,18 @@ static bool FindOptimalMemOpLowering(std::vector &MemOps, return true; } +static bool shouldLowerMemFuncForSize(const MachineFunction &MF) { + const Function *F = MF.getFunction(); + bool HasMinSize = F->hasFnAttribute(Attribute::MinSize); + bool HasOptSize = F->hasFnAttribute(Attribute::OptimizeForSize); + + // On Darwin, -Os means optimize for size without hurting performance, so + // only really optimize for size when -Oz (MinSize) is used. + if (MF.getTarget().getTargetTriple().isOSDarwin()) + return HasMinSize; + return HasOptSize || HasMinSize; +} + static SDValue getMemcpyLoadsAndStores(SelectionDAG &DAG, SDLoc dl, SDValue Chain, SDValue Dst, SDValue Src, uint64_t Size, @@ -4171,7 +4183,7 @@ static SDValue getMemcpyLoadsAndStores(SelectionDAG &DAG, SDLoc dl, bool DstAlignCanChange = false; MachineFunction &MF = DAG.getMachineFunction(); MachineFrameInfo *MFI = MF.getFrameInfo(); - bool OptSize = MF.getFunction()->hasFnAttribute(Attribute::OptimizeForSize); + bool OptSize = shouldLowerMemFuncForSize(MF); FrameIndexSDNode *FI = dyn_cast(Dst); if (FI && !MFI->isFixedObjectIndex(FI->getIndex())) DstAlignCanChange = true; @@ -4284,7 +4296,7 @@ static SDValue getMemmoveLoadsAndStores(SelectionDAG &DAG, SDLoc dl, bool DstAlignCanChange = false; MachineFunction &MF = DAG.getMachineFunction(); MachineFrameInfo *MFI = MF.getFrameInfo(); - bool OptSize = MF.getFunction()->hasFnAttribute(Attribute::OptimizeForSize); + bool OptSize = shouldLowerMemFuncForSize(MF); FrameIndexSDNode *FI = dyn_cast(Dst); if (FI && !MFI->isFixedObjectIndex(FI->getIndex())) DstAlignCanChange = true; @@ -4378,7 +4390,7 @@ static SDValue getMemsetStores(SelectionDAG &DAG, SDLoc dl, bool DstAlignCanChange = false; MachineFunction &MF = DAG.getMachineFunction(); MachineFrameInfo *MFI = MF.getFrameInfo(); - bool OptSize = MF.getFunction()->hasFnAttribute(Attribute::OptimizeForSize); + bool OptSize = shouldLowerMemFuncForSize(MF); FrameIndexSDNode *FI = dyn_cast(Dst); if (FI && !MFI->isFixedObjectIndex(FI->getIndex())) DstAlignCanChange = true; -- cgit v1.2.3