From 30c93e1cd3e43e174994834900325fcff3322288 Mon Sep 17 00:00:00 2001 From: Jim Grosbach Date: Wed, 8 Sep 2010 17:22:12 +0000 Subject: [PATCH] Be more careful about when to do dynamic stack realignment. Since we have an option to disable base pointer usage, pay attention to it when deciding if we can realign (if no base pointer and VLAs, we can't). git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@113366 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Target/ARM/ARMBaseRegisterInfo.cpp | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/lib/Target/ARM/ARMBaseRegisterInfo.cpp b/lib/Target/ARM/ARMBaseRegisterInfo.cpp index b153b68eb9b..7b4086875cc 100644 --- a/lib/Target/ARM/ARMBaseRegisterInfo.cpp +++ b/lib/Target/ARM/ARMBaseRegisterInfo.cpp @@ -667,8 +667,14 @@ bool ARMBaseRegisterInfo::hasBasePointer(const MachineFunction &MF) const { } bool ARMBaseRegisterInfo::canRealignStack(const MachineFunction &MF) const { + const MachineFrameInfo *MFI = MF.getFrameInfo(); const ARMFunctionInfo *AFI = MF.getInfo(); - return (RealignStack && !AFI->isThumb1OnlyFunction()); + // We can't realign the stack if: + // 1. Dynamic stack realignment is explicitly disabled, + // 2. This is a Thumb1 function (it's not useful, so we don't bother), or + // 3. There are VLAs in the function and the base pointer is disabled. + return (RealignStack && !AFI->isThumb1OnlyFunction() && + (!MFI->hasVarSizedObjects() || EnableBasePointer)); } bool ARMBaseRegisterInfo:: @@ -1890,7 +1896,8 @@ emitPrologue(MachineFunction &MF) const { AFI->setGPRCalleeSavedArea2Size(GPRCS2Size); AFI->setDPRCalleeSavedAreaSize(DPRCSSize); - // If we need dynamic stack realignment, do it here. + // If we need dynamic stack realignment, do it here. Be paranoid and make + // sure if we also have VLAs, we have a base pointer for frame access. if (needsStackRealignment(MF)) { unsigned MaxAlign = MFI->getMaxAlignment(); assert (!AFI->isThumb1OnlyFunction());