CodeGen: Handle bundled instructions in two-address-instructions pass

llvm/lib/CodeGen/TwoAddressInstructionPass.cpp

@@ -1665,6 +1665,17 @@ void TwoAddressInstructionImpl::processTiedPairs(MachineInstr *MI,
     // by SubRegB is compatible with RegA with no subregister. So regardless of
     // whether the dest oper writes a subreg, the source oper should not.
     MO.setSubReg(0);
+
+    // Update uses of RegB to uses of RegA inside the bundle.
+    if (MI->isBundle()) {
+      for (MachineOperand &MO : mi_bundle_ops(*MI)) {
+        if (MO.isReg() && MO.getReg() == RegB) {
+          assert(MO.getSubReg() == 0 && SubRegB == 0 &&
+                 "tied subregister uses in bundled instructions not supported");
+          MO.setReg(RegA);
+        }
+      }
+    }
   }
 
   if (AllUsesCopied) {

llvm/test/CodeGen/AMDGPU/twoaddr-bundle.mir

@@ -0,0 +1,57 @@
+# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py UTC_ARGS: --version 6
+# RUN: llc -mtriple=amdgcn -mcpu=gfx1200 %s --passes=two-address-instruction -verify-each -o - | FileCheck --check-prefixes=GCN %s
+
+# Exercise very basic handling of BUNDLE'd instructions by the two-address-instruction pass.
+
+# This test is an example where it is best to keep the two-address instruction
+# and resolve the tie with a COPY that is expected to be coalesced.
+---
+name:            test_fmac_bundle
+body:             |
+  bb.0:
+
+    ; GCN-LABEL: name: test_fmac_bundle
+    ; GCN: [[COPY:%[0-9]+]]:vgpr_32 = COPY $vgpr0
+    ; GCN-NEXT: [[COPY1:%[0-9]+]]:vgpr_32 = COPY $vgpr1
+    ; GCN-NEXT: [[V_ADD_U32_e64_:%[0-9]+]]:vgpr_32 = V_ADD_U32_e64 [[COPY]], [[COPY1]], 0, implicit $exec
+    ; GCN-NEXT: [[DEF:%[0-9]+]]:vgpr_32 = IMPLICIT_DEF
+    ; GCN-NEXT: [[DEF1:%[0-9]+]]:vgpr_32 = IMPLICIT_DEF
+    ; GCN-NEXT: [[COPY2:%[0-9]+]]:vgpr_32 = COPY [[V_ADD_U32_e64_]]
+    ; GCN-NEXT: BUNDLE implicit-def [[COPY2]], implicit [[DEF]], implicit [[DEF1]], implicit [[COPY2]](tied-def 0), implicit $mode, implicit $exec {
+    ; GCN-NEXT:   [[COPY2:%[0-9]+]]:vgpr_32 = V_FMAC_F32_e32 killed [[DEF]], killed [[DEF1]], killed [[COPY2]], implicit $mode, implicit $exec
+    ; GCN-NEXT: }
+    %10:vgpr_32 = COPY $vgpr0
+    %11:vgpr_32 = COPY $vgpr1
+    %2:vgpr_32 = V_ADD_U32_e64 %10, %11, 0, implicit $exec
+    %0:vgpr_32 = IMPLICIT_DEF
+    %1:vgpr_32 = IMPLICIT_DEF
+    BUNDLE implicit-def %3:vgpr_32, implicit %0, implicit %1, implicit killed %2(tied-def 0), implicit $mode, implicit $exec {
+      %3:vgpr_32 = V_FMAC_F32_e32 killed %0, killed %1, killed %2, implicit $mode, implicit $exec
+    }
+
+...
+
+# This test is an example where conversion to three-address form would be beneficial.
+---
+name:            test_fmac_reuse_bundle
+body:             |
+  bb.0:
+
+    ; GCN-LABEL: name: test_fmac_reuse_bundle
+    ; GCN: [[COPY:%[0-9]+]]:vgpr_32 = COPY $vgpr0
+    ; GCN-NEXT: [[DEF:%[0-9]+]]:vgpr_32 = IMPLICIT_DEF
+    ; GCN-NEXT: [[DEF1:%[0-9]+]]:vgpr_32 = IMPLICIT_DEF
+    ; GCN-NEXT: [[COPY1:%[0-9]+]]:vgpr_32 = COPY [[COPY]]
+    ; GCN-NEXT: BUNDLE implicit-def [[COPY1]], implicit [[DEF]], implicit [[DEF1]], implicit [[COPY1]](tied-def 0), implicit $mode, implicit $exec {
+    ; GCN-NEXT:   [[COPY1:%[0-9]+]]:vgpr_32 = V_FMAC_F32_e32 killed [[DEF]], killed [[DEF1]], killed [[COPY1]], implicit $mode, implicit $exec
+    ; GCN-NEXT: }
+    ; GCN-NEXT: [[V_ADD_U32_e64_:%[0-9]+]]:vgpr_32 = V_ADD_U32_e64 [[COPY1]], [[COPY]], 0, implicit $exec
+    %2:vgpr_32 = COPY $vgpr0
+    %0:vgpr_32 = IMPLICIT_DEF
+    %1:vgpr_32 = IMPLICIT_DEF
+    BUNDLE implicit-def %3:vgpr_32, implicit %0, implicit %1, implicit %2(tied-def 0), implicit $mode, implicit $exec {
+      %3:vgpr_32 = V_FMAC_F32_e32 killed %0, killed %1, killed %2, implicit $mode, implicit $exec
+    }
+    %4:vgpr_32 = V_ADD_U32_e64 %3, %2, 0, implicit $exec
+
+...