Add support for dynamic stack realignment when in thumb1 mode.
rdar://10288916
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@142337 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/ARM/ARMBaseRegisterInfo.cpp b/lib/Target/ARM/ARMBaseRegisterInfo.cpp
index 7c42342..48e3c52 100644
--- a/lib/Target/ARM/ARMBaseRegisterInfo.cpp
+++ b/lib/Target/ARM/ARMBaseRegisterInfo.cpp
@@ -626,13 +626,10 @@
bool ARMBaseRegisterInfo::canRealignStack(const MachineFunction &MF) const {
const MachineFrameInfo *MFI = MF.getFrameInfo();
- const ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>();
// 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));
+ // 2. There are VLAs in the function and the base pointer is disabled.
+ return (RealignStack && (!MFI->hasVarSizedObjects() || EnableBasePointer));
}
bool ARMBaseRegisterInfo::
diff --git a/lib/Target/ARM/ARMFrameLowering.cpp b/lib/Target/ARM/ARMFrameLowering.cpp
index 2d1de6f..4bac6c5 100644
--- a/lib/Target/ARM/ARMFrameLowering.cpp
+++ b/lib/Target/ARM/ARMFrameLowering.cpp
@@ -881,10 +881,12 @@
// for sure what the stack size will be, but for this, an estimate is good
// enough. If there anything changes it, it'll be a spill, which implies
// we've used all the registers and so R4 is already used, so not marking
- // it here will be OK.
+ // it here will be OK. Also spill R4 if Thumb1 function requires stack
+ // realignment.
// FIXME: It will be better just to find spare register here.
unsigned StackSize = estimateStackSize(MF);
- if (MFI->hasVarSizedObjects() || StackSize > 508)
+ if (MFI->hasVarSizedObjects() || RegInfo->needsStackRealignment(MF) ||
+ StackSize > 508)
MF.getRegInfo().setPhysRegUsed(ARM::R4);
}
diff --git a/lib/Target/ARM/Thumb1FrameLowering.cpp b/lib/Target/ARM/Thumb1FrameLowering.cpp
index d848177..ad1edc8 100644
--- a/lib/Target/ARM/Thumb1FrameLowering.cpp
+++ b/lib/Target/ARM/Thumb1FrameLowering.cpp
@@ -155,10 +155,32 @@
AFI->setGPRCalleeSavedArea2Size(GPRCS2Size);
AFI->setDPRCalleeSavedAreaSize(DPRCSSize);
- // Thumb1 does not currently support dynamic stack realignment. Report a
- // fatal error rather then silently generate bad code.
- if (RegInfo->needsStackRealignment(MF))
- report_fatal_error("Dynamic stack realignment not supported for thumb1.");
+ // 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 (RegInfo->needsStackRealignment(MF)) {
+ // We cannot use sp as source/dest register here, thus we're emitting the
+ // following sequence:
+ // mov r4, sp
+ // lsrs r4, r4, Log2MaxAlign
+ // lsls r4, r4, Log2MaxAlign
+ // mov sp, r4
+ unsigned MaxAlign = MFI->getMaxAlignment();
+ unsigned Log2MaxAlign = Log2_32(MaxAlign);
+ AddDefaultPred(BuildMI(MBB, MBBI, dl, TII.get(ARM::tMOVr), ARM::R4)
+ .addReg(ARM::SP, RegState::Kill));
+ AddDefaultPred(AddDefaultT1CC(BuildMI(MBB, MBBI, dl, TII.get(ARM::tLSRri),
+ ARM::R4))
+ .addReg(ARM::R4, RegState::Kill)
+ .addImm(Log2MaxAlign));
+ AddDefaultPred(AddDefaultT1CC(BuildMI(MBB, MBBI, dl, TII.get(ARM::tLSLri),
+ ARM::R4))
+ .addReg(ARM::R4, RegState::Kill)
+ .addImm(Log2MaxAlign));
+ AddDefaultPred(BuildMI(MBB, MBBI, dl, TII.get(ARM::tMOVr), ARM::SP)
+ .addReg(ARM::R4, RegState::Kill));
+
+ AFI->setShouldRestoreSPFromFP(true);
+ }
// If we need a base pointer, set it up here. It's whatever the value
// of the stack pointer is at this point. Any variable size objects