Add SrcReg2 to analyzeCompare and optimizeCompareInstr to handle Compare
instructions with two register operands.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@159465 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/ARM/ARMBaseInstrInfo.cpp b/lib/Target/ARM/ARMBaseInstrInfo.cpp
index 3a180df..88fe6f9 100644
--- a/lib/Target/ARM/ARMBaseInstrInfo.cpp
+++ b/lib/Target/ARM/ARMBaseInstrInfo.cpp
@@ -1737,26 +1737,33 @@
return Offset == 0;
}
+/// analyzeCompare - For a comparison instruction, return the source registers
+/// in SrcReg and SrcReg2 if having two register operands, and the value it
+/// compares against in CmpValue. Return true if the comparison instruction
+/// can be analyzed.
bool ARMBaseInstrInfo::
-AnalyzeCompare(const MachineInstr *MI, unsigned &SrcReg, int &CmpMask,
- int &CmpValue) const {
+analyzeCompare(const MachineInstr *MI, unsigned &SrcReg, unsigned &SrcReg2,
+ int &CmpMask, int &CmpValue) const {
switch (MI->getOpcode()) {
default: break;
case ARM::CMPri:
case ARM::t2CMPri:
SrcReg = MI->getOperand(0).getReg();
+ SrcReg2 = 0;
CmpMask = ~0;
CmpValue = MI->getOperand(1).getImm();
return true;
case ARM::CMPrr:
case ARM::t2CMPrr:
SrcReg = MI->getOperand(0).getReg();
+ SrcReg2 = MI->getOperand(1).getReg();
CmpMask = ~0;
CmpValue = 0;
return true;
case ARM::TSTri:
case ARM::t2TSTri:
SrcReg = MI->getOperand(0).getReg();
+ SrcReg2 = 0;
CmpMask = MI->getOperand(1).getImm();
CmpValue = 0;
return true;
@@ -1794,14 +1801,17 @@
return false;
}
-/// OptimizeCompareInstr - Convert the instruction supplying the argument to the
-/// comparison into one that sets the zero bit in the flags register. Convert
-/// the SUBrr(r1,r2)|Subri(r1,CmpValue) instruction into one that sets the flags
-/// register and remove the CMPrr(r1,r2)|CMPrr(r2,r1)|CMPri(r1,CmpValue)
-/// instruction.
+/// optimizeCompareInstr - Convert the instruction supplying the argument to the
+/// comparison into one that sets the zero bit in the flags register;
+/// Remove a redundant Compare instruction if an earlier instruction can set the
+/// flags in the same way as Compare.
+/// E.g. SUBrr(r1,r2) and CMPrr(r1,r2). We also handle the case where two
+/// operands are swapped: SUBrr(r1,r2) and CMPrr(r2,r1), by updating the
+/// condition code of instructions which use the flags.
bool ARMBaseInstrInfo::
-OptimizeCompareInstr(MachineInstr *CmpInstr, unsigned SrcReg, int CmpMask,
- int CmpValue, const MachineRegisterInfo *MRI) const {
+optimizeCompareInstr(MachineInstr *CmpInstr, unsigned SrcReg, unsigned SrcReg2,
+ int CmpMask, int CmpValue,
+ const MachineRegisterInfo *MRI) const {
if (MRI->def_empty(SrcReg))
return false;
@@ -1841,13 +1851,10 @@
// For CMPrr(r1,r2), we are looking for SUB(r1,r2) or SUB(r2,r1).
// For CMPri(r1, CmpValue), we are looking for SUBri(r1, CmpValue).
MachineInstr *Sub = NULL;
- unsigned SrcReg2 = 0;
- if (CmpInstr->getOpcode() == ARM::CMPrr ||
- CmpInstr->getOpcode() == ARM::t2CMPrr) {
- SrcReg2 = CmpInstr->getOperand(1).getReg();
+ if (SrcReg2 != 0)
// MI is not a candidate for CMPrr.
MI = NULL;
- } else if (MI->getParent() != CmpInstr->getParent() || CmpValue != 0) {
+ else if (MI->getParent() != CmpInstr->getParent() || CmpValue != 0) {
// Conservatively refuse to convert an instruction which isn't in the same
// BB as the comparison.
// For CMPri, we need to check Sub, thus we can't return here.