[llvm] [PPC]Optimize zeroing accumulator and spilling instructions into simple instructions (PR #96094)
Chen Zheng via llvm-commits
llvm-commits at lists.llvm.org
Mon Jun 24 20:26:53 PDT 2024
================
@@ -109,6 +109,93 @@ static bool hasPCRelativeForm(MachineInstr &Use) {
MachineFunctionProperties::Property::NoVRegs);
}
+ // The funtion will simply the zeroing accumulator and spilling instrcutions
+ // into simple xxlxor and spilling instrcuctions.
+ // From:
+ // setaccz acci
+ // xxmfacc acci
+ // stxv vsr(i*4+0), D(1)
+ // stxv vsr(i*4+1), D-16(1)
+ // stxv vsr(i*4+2), D-32(1)
+ // stxv vsr(i*4+3), D-48(1)
+
+ // To:
+ // xxlxor vsr(i*4), 0, 0
+ // stxv vsr(i*4), D(1)
+ // stxv vsr(i*4), D-16(1)
+ // stxv vsr(i*4), D-32(1)
+ // stxv vsr(i*4), D-48(1)
+ bool
+ OptimizeZeroingAccumulatorSpilling(MachineBasicBlock &MBB,
+ const TargetRegisterInfo *TRI) const {
+ bool changed = false;
+ for (auto BBI = MBB.instr_begin(); BBI != MBB.instr_end(); ++BBI) {
+ if (BBI->getOpcode() != PPC::XXSETACCZ)
+ continue;
+
+ Register ACCZReg = BBI->getOperand(0).getReg();
+
+ DenseSet<MachineInstr *> InstrsToErase;
+ InstrsToErase.insert(&*BBI++);
+
+ if (BBI->getOpcode() != PPC::XXMFACC) {
+ --BBI;
+ continue;
+ }
+
+ Register ACCWReg = BBI->getOperand(0).getReg();
+
+ if (ACCWReg != ACCZReg)
+ continue;
+
+ auto XXMFACCInstr = BBI;
+ InstrsToErase.insert(&*BBI++);
+
+ Register VSLRegBase = (ACCWReg - PPC::ACC0) * 4 + PPC::VSL0;
+ bool isVSLRegBaseKilled = false;
+ for (unsigned InstrCount = 0; InstrCount < 4; ++InstrCount, ++BBI) {
+ if (BBI->getOpcode() == PPC::STXV) {
+ Register Reg0 = BBI->getOperand(0).getReg();
+ // If the VSLRegBase Register is killed, we put the kill in the
+ // last STXV instruction.
----------------
chenzheng1030 wrote:
Add a FIXME here that we may need to update killed flag for other vsr as well.
https://github.com/llvm/llvm-project/pull/96094
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