Changes in directory llvm/lib/Target/ARM:
ARMRegisterInfo.cpp updated: 1.77 -> 1.78
---
Log message:
Use a spilled free callee-saved register as scratch register.
---
Diffs of the changes: (+17 -3)
ARMRegisterInfo.cpp | 20 +++++++++++++++++---
1 files changed, 17 insertions(+), 3 deletions(-)
Index: llvm/lib/Target/ARM/ARMRegisterInfo.cpp
diff -u llvm/lib/Target/ARM/ARMRegisterInfo.cpp:1.77
llvm/lib/Target/ARM/ARMRegisterInfo.cpp:1.78
--- llvm/lib/Target/ARM/ARMRegisterInfo.cpp:1.77 Thu Mar 1 02:26:31 2007
+++ llvm/lib/Target/ARM/ARMRegisterInfo.cpp Thu Mar 1 02:57:52 2007
@@ -313,6 +313,7 @@
}
BitVector ARMRegisterInfo::getReservedRegs(const MachineFunction &MF) const {
+ // FIXME: avoid re-calculating this everytime.
BitVector Reserved(getNumRegs());
Reserved.set(ARM::SP);
Reserved.set(ARM::PC);
@@ -619,6 +620,20 @@
.addReg(DestReg, false, false, true);
}
+/// findScratchRegister - Find a 'free' ARM register. If register scavenger
+/// is not being used, R12 is available. Otherwise, try for a call-clobbered
+/// register first and then a spilled callee-saved register if that fails.
+static
+unsigned findScratchRegister(RegScavenger *RS, const TargetRegisterClass *RC,
+ ARMFunctionInfo *AFI) {
+ unsigned Reg = RS ? RS->FindUnusedReg(RC, true) : (unsigned) ARM::R12;
+ if (Reg == 0)
+ // Try a already spilled CS register.
+ Reg = RS->FindUnusedReg(RC, AFI->getSpilledCSRegisters());
+
+ return Reg;
+}
+
void ARMRegisterInfo::eliminateFrameIndex(MachineBasicBlock::iterator II,
RegScavenger *RS) const{
unsigned i = 0;
@@ -902,9 +917,8 @@
// If the offset we have is too large to fit into the instruction, we need
// to form it with a series of ADDri's. Do this by taking 8-bit chunks
// out of 'Offset'.
- unsigned ScratchReg = RS
- ? RS->FindUnusedReg(&ARM::GPRRegClass, true) : (unsigned)ARM::R12;
- assert(ScratchReg != 0 && "Unable to find a free call-clobbered
register!");
+ unsigned ScratchReg = findScratchRegister(RS, &ARM::GPRRegClass, AFI);
+ assert(ScratchReg && "Unable to find a free register!");
emitARMRegPlusImmediate(MBB, II, ScratchReg, FrameReg,
isSub ? -Offset : Offset, TII);
MI.getOperand(i).ChangeToRegister(ScratchReg, false, false, true);
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