[llvm-branch-commits] [llvm] AMDGPU/GlobalISel: Improve readanylane combines in regbanklegalize (PR #145911)

[Nicolai Hähnle via llvm-branch-commits]

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@@ -115,126 +117,233 @@ class AMDGPURegBankLegalizeCombiner {
         VgprRB(&RBI.getRegBank(AMDGPU::VGPRRegBankID)),
         VccRB(&RBI.getRegBank(AMDGPU::VCCRegBankID)) {};
 
-  bool isLaneMask(Register Reg) {
-    const RegisterBank *RB = MRI.getRegBankOrNull(Reg);
-    if (RB && RB->getID() == AMDGPU::VCCRegBankID)
-      return true;
+  bool isLaneMask(Register Reg);
+  std::pair<MachineInstr *, Register> tryMatch(Register Src, unsigned Opcode);
+  std::pair<GUnmerge *, int> tryMatchRALFromUnmerge(Register Src);
+  Register getReadAnyLaneSrc(Register Src);
+  void replaceRegWithOrBuildCopy(Register Dst, Register Src);
 
-    const TargetRegisterClass *RC = MRI.getRegClassOrNull(Reg);
-    return RC && TRI.isSGPRClass(RC) && MRI.getType(Reg) == LLT::scalar(1);
-  }
+  bool tryEliminateReadAnyLane(MachineInstr &Copy);
+  void tryCombineCopy(MachineInstr &MI);
+  void tryCombineS1AnyExt(MachineInstr &MI);
+};
 
-  void cleanUpAfterCombine(MachineInstr &MI, MachineInstr *Optional0) {
-    MI.eraseFromParent();
-    if (Optional0 && isTriviallyDead(*Optional0, MRI))
-      Optional0->eraseFromParent();
-  }
+bool AMDGPURegBankLegalizeCombiner::isLaneMask(Register Reg) {
+  const RegisterBank *RB = MRI.getRegBankOrNull(Reg);
+  if (RB && RB->getID() == AMDGPU::VCCRegBankID)
+    return true;
 
-  std::pair<MachineInstr *, Register> tryMatch(Register Src, unsigned Opcode) {
-    MachineInstr *MatchMI = MRI.getVRegDef(Src);
-    if (MatchMI->getOpcode() != Opcode)
-      return {nullptr, Register()};
-    return {MatchMI, MatchMI->getOperand(1).getReg()};
-  }
+  const TargetRegisterClass *RC = MRI.getRegClassOrNull(Reg);
+  return RC && TRI.isSGPRClass(RC) && MRI.getType(Reg) == LLT::scalar(1);
+}
 
-  void tryCombineCopy(MachineInstr &MI) {
-    Register Dst = MI.getOperand(0).getReg();
-    Register Src = MI.getOperand(1).getReg();
-    // Skip copies of physical registers.
-    if (!Dst.isVirtual() || !Src.isVirtual())
-      return;
-
-    // This is a cross bank copy, sgpr S1 to lane mask.
-    //
-    // %Src:sgpr(s1) = G_TRUNC %TruncS32Src:sgpr(s32)
-    // %Dst:lane-mask(s1) = COPY %Src:sgpr(s1)
-    // ->
-    // %Dst:lane-mask(s1) = G_AMDGPU_COPY_VCC_SCC %TruncS32Src:sgpr(s32)
-    if (isLaneMask(Dst) && MRI.getRegBankOrNull(Src) == SgprRB) {
-      auto [Trunc, TruncS32Src] = tryMatch(Src, AMDGPU::G_TRUNC);
-      assert(Trunc && MRI.getType(TruncS32Src) == S32 &&
-             "sgpr S1 must be result of G_TRUNC of sgpr S32");
-
-      B.setInstr(MI);
-      // Ensure that truncated bits in BoolSrc are 0.
-      auto One = B.buildConstant({SgprRB, S32}, 1);
-      auto BoolSrc = B.buildAnd({SgprRB, S32}, TruncS32Src, One);
-      B.buildInstr(AMDGPU::G_AMDGPU_COPY_VCC_SCC, {Dst}, {BoolSrc});
-      cleanUpAfterCombine(MI, Trunc);
-      return;
-    }
+std::pair<MachineInstr *, Register>
+AMDGPURegBankLegalizeCombiner::tryMatch(Register Src, unsigned Opcode) {
+  MachineInstr *MatchMI = MRI.getVRegDef(Src);
+  if (MatchMI->getOpcode() != Opcode)
+    return {nullptr, Register()};
+  return {MatchMI, MatchMI->getOperand(1).getReg()};
+}
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nhaehnle wrote:

Is there a better name for this than `tryMatch`? Come to think of it, can the generic matching infrastructure be used for this?

https://github.com/llvm/llvm-project/pull/145911