Careful with reg_sequence coalescing to not to overwrite sub-register indices.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@103971 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/TwoAddressInstructionPass.cpp b/lib/CodeGen/TwoAddressInstructionPass.cpp
index 80bb1a9..fb9bddc 100644
--- a/lib/CodeGen/TwoAddressInstructionPass.cpp
+++ b/lib/CodeGen/TwoAddressInstructionPass.cpp
@@ -128,6 +128,8 @@
void ProcessCopy(MachineInstr *MI, MachineBasicBlock *MBB,
SmallPtrSet<MachineInstr*, 8> &Processed);
+ void CoalesceExtSubRegs(SmallVector<unsigned,4> &Srcs, unsigned DstReg);
+
/// EliminateRegSequences - Eliminate REG_SEQUENCE instructions as part
/// of the de-ssa process. This replaces sources of REG_SEQUENCE as
/// sub-register references of the register defined by REG_SEQUENCE.
@@ -1132,7 +1134,7 @@
}
static void UpdateRegSequenceSrcs(unsigned SrcReg,
- unsigned DstReg, unsigned SrcIdx,
+ unsigned DstReg, unsigned SubIdx,
MachineRegisterInfo *MRI) {
for (MachineRegisterInfo::reg_iterator RI = MRI->reg_begin(SrcReg),
RE = MRI->reg_end(); RI != RE; ) {
@@ -1140,7 +1142,77 @@
++RI;
MO.setReg(DstReg);
assert(MO.getSubReg() == 0);
- MO.setSubReg(SrcIdx);
+ MO.setSubReg(SubIdx);
+ }
+}
+
+/// CoalesceExtSubRegs - If a number of sources of the REG_SEQUENCE are
+/// EXTRACT_SUBREG from the same register and to the same virtual register
+/// with different sub-register indices, attempt to combine the
+/// EXTRACT_SUBREGs and pre-coalesce them. e.g.
+/// %reg1026<def> = VLDMQ %reg1025<kill>, 260, pred:14, pred:%reg0
+/// %reg1029:6<def> = EXTRACT_SUBREG %reg1026, 6
+/// %reg1029:5<def> = EXTRACT_SUBREG %reg1026<kill>, 5
+/// Since D subregs 5, 6 can combine to a Q register, we can coalesce
+/// reg1026 to reg1029.
+void
+TwoAddressInstructionPass::CoalesceExtSubRegs(SmallVector<unsigned,4> &Srcs,
+ unsigned DstReg) {
+ SmallSet<unsigned, 4> Seen;
+ for (unsigned i = 0, e = Srcs.size(); i != e; ++i) {
+ unsigned SrcReg = Srcs[i];
+ if (!Seen.insert(SrcReg))
+ continue;
+
+ // If there are no other uses than extract_subreg which feed into
+ // the reg_sequence, then we might be able to coalesce them.
+ bool CanCoalesce = true;
+ SmallVector<unsigned, 4> SubIndices;
+ for (MachineRegisterInfo::use_nodbg_iterator
+ UI = MRI->use_nodbg_begin(SrcReg),
+ UE = MRI->use_nodbg_end(); UI != UE; ++UI) {
+ MachineInstr *UseMI = &*UI;
+ if (!UseMI->isExtractSubreg() ||
+ UseMI->getOperand(0).getReg() != DstReg) {
+ CanCoalesce = false;
+ break;
+ }
+ SubIndices.push_back(UseMI->getOperand(2).getImm());
+ }
+
+ if (!CanCoalesce || SubIndices.size() < 2)
+ continue;
+
+ std::sort(SubIndices.begin(), SubIndices.end());
+ unsigned NewSubIdx = 0;
+ if (TRI->canCombinedSubRegIndex(MRI->getRegClass(SrcReg), SubIndices,
+ NewSubIdx)) {
+ bool Proceed = true;
+ if (NewSubIdx)
+ for (MachineRegisterInfo::reg_iterator RI = MRI->reg_begin(SrcReg),
+ RE = MRI->reg_end(); RI != RE; ) {
+ MachineOperand &MO = RI.getOperand();
+ ++RI;
+ // FIXME: If the sub-registers do not combine to the whole
+ // super-register, i.e. NewSubIdx != 0, and any of the use has a
+ // sub-register index, then abort the coalescing attempt.
+ if (MO.getSubReg()) {
+ Proceed = false;
+ break;
+ }
+ MO.setReg(DstReg);
+ MO.setSubReg(NewSubIdx);
+ }
+ if (Proceed)
+ for (MachineRegisterInfo::reg_iterator RI = MRI->reg_begin(SrcReg),
+ RE = MRI->reg_end(); RI != RE; ) {
+ MachineOperand &MO = RI.getOperand();
+ ++RI;
+ MO.setReg(DstReg);
+ if (NewSubIdx)
+ MO.setSubReg(NewSubIdx);
+ }
+ }
}
}
@@ -1221,50 +1293,15 @@
for (unsigned i = 1, e = MI->getNumOperands(); i < e; i += 2) {
unsigned SrcReg = MI->getOperand(i).getReg();
- unsigned SrcIdx = MI->getOperand(i+1).getImm();
- UpdateRegSequenceSrcs(SrcReg, DstReg, SrcIdx, MRI);
+ unsigned SubIdx = MI->getOperand(i+1).getImm();
+ UpdateRegSequenceSrcs(SrcReg, DstReg, SubIdx, MRI);
}
DEBUG(dbgs() << "Eliminated: " << *MI);
MI->eraseFromParent();
// Try coalescing some EXTRACT_SUBREG instructions.
- Seen.clear();
- for (unsigned i = 0, e = RealSrcs.size(); i != e; ++i) {
- unsigned SrcReg = RealSrcs[i];
- if (!Seen.insert(SrcReg))
- continue;
-
- // If there are no other uses than extract_subreg which feed into
- // the reg_sequence, then we might be able to coalesce them.
- bool CanCoalesce = true;
- SmallVector<unsigned, 4> SubIndices;
- for (MachineRegisterInfo::use_nodbg_iterator
- UI = MRI->use_nodbg_begin(SrcReg),
- UE = MRI->use_nodbg_end(); UI != UE; ++UI) {
- MachineInstr *UseMI = &*UI;
- if (!UseMI->isExtractSubreg() ||
- UseMI->getOperand(0).getReg() != DstReg) {
- CanCoalesce = false;
- break;
- }
- SubIndices.push_back(UseMI->getOperand(2).getImm());
- }
-
- if (!CanCoalesce)
- continue;
-
- // %reg1026<def> = VLDMQ %reg1025<kill>, 260, pred:14, pred:%reg0
- // %reg1029:6<def> = EXTRACT_SUBREG %reg1026, 6
- // %reg1029:5<def> = EXTRACT_SUBREG %reg1026<kill>, 5
- // Since D subregs 5, 6 can combine to a Q register, we can coalesce
- // reg1026 to reg1029.
- std::sort(SubIndices.begin(), SubIndices.end());
- unsigned NewSubIdx = 0;
- if (TRI->canCombinedSubRegIndex(MRI->getRegClass(SrcReg), SubIndices,
- NewSubIdx))
- UpdateRegSequenceSrcs(SrcReg, DstReg, NewSubIdx, MRI);
- }
+ CoalesceExtSubRegs(RealSrcs, DstReg);
}
RegSequences.clear();