[PATCH] D80158: [AMDGPU] Fix for the lost CarryOut/CarryIn register operands in S_ADD/SUB_CO_PSEUDO.

[Alexander via Phabricator via llvm-commits]

alex-t created this revision.
alex-t added a reviewer: rampitec.
Herald added subscribers: kerbowa, hiraditya, t-tye, tpr, dstuttard, yaxunl, nhaehnle, wdng, jvesely, kzhuravl, arsenm.
Herald added a project: LLVM.

This fixes the 5b898bddff51 <https://reviews.llvm.org/rG5b898bddff51b03479e7223c0241487acace804a> bug when the carry-in and carry-out registers became lost in lowering S_ADD/SUB_CO_PSEUDO.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D80158

Files:
  llvm/lib/Target/AMDGPU/SIInstrInfo.cpp


Index: llvm/lib/Target/AMDGPU/SIInstrInfo.cpp
===================================================================
--- llvm/lib/Target/AMDGPU/SIInstrInfo.cpp
+++ llvm/lib/Target/AMDGPU/SIInstrInfo.cpp
@@ -5177,18 +5177,25 @@
                          ? AMDGPU::V_ADDC_U32_e64
                          : AMDGPU::V_SUBB_U32_e64;
       const auto *CarryRC = RI.getRegClass(AMDGPU::SReg_1_XEXECRegClassID);
-      Register DummyCReg = MRI.createVirtualRegister(CarryRC);
-      Register CarryReg = MRI.createVirtualRegister(CarryRC);
+
+      Register CarryInReg = Inst.getOperand(4).getReg();
+      const TargetRegisterClass *CarryInRC = MRI.getRegClass(CarryInReg);
+      if (CarryInRC != CarryRC) {
+        Register NewCarryReg = MRI.createVirtualRegister(CarryRC);
+        BuildMI(*MBB, &Inst, Inst.getDebugLoc(), get(AMDGPU::COPY), NewCarryReg)
+            .addReg(CarryInReg);
+      }
+
+      Register CarryOutReg = Inst.getOperand(1).getReg();
+
       Register DestReg = MRI.createVirtualRegister(RI.getEquivalentVGPRClass(
           MRI.getRegClass(Inst.getOperand(0).getReg())));
-      BuildMI(*MBB, &Inst, Inst.getDebugLoc(), get(AMDGPU::COPY), CarryReg)
-          .addReg(Inst.getOperand(4).getReg());
       MachineInstr *CarryOp =
           BuildMI(*MBB, &Inst, Inst.getDebugLoc(), get(Opc), DestReg)
-              .addReg(DummyCReg, RegState::Define | RegState::Dead)
+              .addReg(CarryOutReg, RegState::Define)
               .add(Inst.getOperand(2))
               .add(Inst.getOperand(3))
-              .addReg(CarryReg, RegState::Kill)
+              .addReg(CarryInReg)
               .addImm(0);
       legalizeOperands(*CarryOp);
       MRI.replaceRegWith(Inst.getOperand(0).getReg(), DestReg);


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