aboutsummaryrefslogtreecommitdiffstats
path: root/lib/CodeGen
diff options
context:
space:
mode:
Diffstat (limited to 'lib/CodeGen')
-rw-r--r--lib/CodeGen/TwoAddressInstructionPass.cpp43
1 files changed, 31 insertions, 12 deletions
diff --git a/lib/CodeGen/TwoAddressInstructionPass.cpp b/lib/CodeGen/TwoAddressInstructionPass.cpp
index ec2b577..c87ab64 100644
--- a/lib/CodeGen/TwoAddressInstructionPass.cpp
+++ b/lib/CodeGen/TwoAddressInstructionPass.cpp
@@ -1456,6 +1456,19 @@ bool TwoAddressInstructionPass::runOnMachineFunction(MachineFunction &MF) {
"two address instruction invalid");
unsigned regB = mi->getOperand(SrcIdx).getReg();
+
+ // Deal with <undef> uses immediately - simply rewrite the src operand.
+ if (mi->getOperand(SrcIdx).isUndef()) {
+ unsigned DstReg = mi->getOperand(DstIdx).getReg();
+ // Constrain the DstReg register class if required.
+ if (TargetRegisterInfo::isVirtualRegister(DstReg))
+ if (const TargetRegisterClass *RC = TII->getRegClass(MCID, SrcIdx,
+ TRI, MF))
+ MRI->constrainRegClass(DstReg, RC);
+ mi->getOperand(SrcIdx).setReg(DstReg);
+ DEBUG(dbgs() << "\t\trewrite undef:\t" << *mi);
+ continue;
+ }
TiedOperands[regB].push_back(std::make_pair(SrcIdx, DstIdx));
}
@@ -1609,19 +1622,20 @@ bool TwoAddressInstructionPass::runOnMachineFunction(MachineFunction &MF) {
MadeChange = true;
DEBUG(dbgs() << "\t\trewrite to:\t" << *mi);
+ }
- // Rewrite INSERT_SUBREG as COPY now that we no longer need SSA form.
- if (mi->isInsertSubreg()) {
- // From %reg = INSERT_SUBREG %reg, %subreg, subidx
- // To %reg:subidx = COPY %subreg
- unsigned SubIdx = mi->getOperand(3).getImm();
- mi->RemoveOperand(3);
- assert(mi->getOperand(0).getSubReg() == 0 && "Unexpected subreg idx");
- mi->getOperand(0).setSubReg(SubIdx);
- mi->RemoveOperand(1);
- mi->setDesc(TII->get(TargetOpcode::COPY));
- DEBUG(dbgs() << "\t\tconvert to:\t" << *mi);
- }
+ // Rewrite INSERT_SUBREG as COPY now that we no longer need SSA form.
+ if (mi->isInsertSubreg()) {
+ // From %reg = INSERT_SUBREG %reg, %subreg, subidx
+ // To %reg:subidx = COPY %subreg
+ unsigned SubIdx = mi->getOperand(3).getImm();
+ mi->RemoveOperand(3);
+ assert(mi->getOperand(0).getSubReg() == 0 && "Unexpected subreg idx");
+ mi->getOperand(0).setSubReg(SubIdx);
+ mi->getOperand(0).setIsUndef(mi->getOperand(1).isUndef());
+ mi->RemoveOperand(1);
+ mi->setDesc(TII->get(TargetOpcode::COPY));
+ DEBUG(dbgs() << "\t\tconvert to:\t" << *mi);
}
// Clear TiedOperands here instead of at the top of the loop
@@ -1846,6 +1860,11 @@ bool TwoAddressInstructionPass::EliminateRegSequences() {
SmallVector<unsigned, 4> RealSrcs;
SmallSet<unsigned, 4> Seen;
for (unsigned i = 1, e = MI->getNumOperands(); i < e; i += 2) {
+ // Nothing needs to be inserted for <undef> operands.
+ if (MI->getOperand(i).isUndef()) {
+ MI->getOperand(i).setReg(0);
+ continue;
+ }
unsigned SrcReg = MI->getOperand(i).getReg();
unsigned SrcSubIdx = MI->getOperand(i).getSubReg();
unsigned SubIdx = MI->getOperand(i+1).getImm();