PR7458: Try commuting Thumb2 instruction operands to put them into 2-address
form so they can be narrowed to 16-bit instructions.
llvm-svn: 106762
diff --git a/llvm/lib/Target/ARM/Thumb2SizeReduction.cpp b/llvm/lib/Target/ARM/Thumb2SizeReduction.cpp
index 4ad21c4..ba392f3 100644
--- a/llvm/lib/Target/ARM/Thumb2SizeReduction.cpp
+++ b/llvm/lib/Target/ARM/Thumb2SizeReduction.cpp
@@ -451,11 +451,18 @@
if (ReduceLimit2Addr != -1 && ((int)Num2Addrs >= ReduceLimit2Addr))
return false;
- const TargetInstrDesc &TID = MI->getDesc();
unsigned Reg0 = MI->getOperand(0).getReg();
unsigned Reg1 = MI->getOperand(1).getReg();
- if (Reg0 != Reg1)
- return false;
+ if (Reg0 != Reg1) {
+ // Try to commute the operands to make it a 2-address instruction.
+ unsigned CommOpIdx1, CommOpIdx2;
+ if (!TII->findCommutedOpIndices(MI, CommOpIdx1, CommOpIdx2) ||
+ CommOpIdx1 != 1 || MI->getOperand(CommOpIdx2).getReg() != Reg0)
+ return false;
+ MachineInstr *CommutedMI = TII->commuteInstruction(MI);
+ if (!CommutedMI)
+ return false;
+ }
if (Entry.LowRegs2 && !isARMLowRegister(Reg0))
return false;
if (Entry.Imm2Limit) {
@@ -484,6 +491,7 @@
bool HasCC = false;
bool CCDead = false;
+ const TargetInstrDesc &TID = MI->getDesc();
if (TID.hasOptionalDef()) {
unsigned NumOps = TID.getNumOperands();
HasCC = (MI->getOperand(NumOps-1).getReg() == ARM::CPSR);