[PATCH] D85122: [GlobalISel][InlineAsm] Fix matching input constraint to physreg

[Petar Avramovic via Phabricator via llvm-commits]

Petar.Avramovic created this revision.
Petar.Avramovic added reviewers: jrtc27, kschwarz, arsenm.
Herald added subscribers: llvm-commits, hiraditya, rovka.
Herald added a project: LLVM.
Petar.Avramovic requested review of this revision.
Herald added a subscriber: wdng.

Simply add given input and mark it as tied.
Doesn't create additional copy compared to
matching input constraint to virtual register.


https://reviews.llvm.org/D85122

Files:
  llvm/lib/CodeGen/GlobalISel/InlineAsmLowering.cpp
  llvm/test/CodeGen/AArch64/GlobalISel/irtranslator-inline-asm.ll


Index: llvm/test/CodeGen/AArch64/GlobalISel/irtranslator-inline-asm.ll
===================================================================
--- llvm/test/CodeGen/AArch64/GlobalISel/irtranslator-inline-asm.ll
+++ llvm/test/CodeGen/AArch64/GlobalISel/irtranslator-inline-asm.ll
@@ -243,3 +243,15 @@
   %1 = call i16 asm sideeffect "", "=r,0"(i16 1)
   ret i16 %1
 }
+
+define i64 @test_input_with_matching_constraint_to_physical_register() {
+  ; CHECK-LABEL: name: test_input_with_matching_constraint_to_physical_register
+  ; CHECK: bb.1 (%ir-block.0):
+  ; CHECK:   [[C:%[0-9]+]]:_(s64) = G_CONSTANT i64 0
+  ; CHECK:   INLINEASM &"", 0 /* attdialect */, 10 /* regdef */, implicit-def $x2, 2147483657 /* reguse tiedto:$0 */, [[C]](tied-def 3)(s64)
+  ; CHECK:   [[COPY:%[0-9]+]]:_(s64) = COPY $x2
+  ; CHECK:   $x0 = COPY [[COPY]](s64)
+  ; CHECK:   RET_ReallyLR implicit $x0
+  %1 = tail call i64 asm "", "={x2},0"(i64 0)
+  ret i64 %1
+}
Index: llvm/lib/CodeGen/GlobalISel/InlineAsmLowering.cpp
===================================================================
--- llvm/lib/CodeGen/GlobalISel/InlineAsmLowering.cpp
+++ llvm/lib/CodeGen/GlobalISel/InlineAsmLowering.cpp
@@ -455,19 +455,22 @@
         unsigned DefRegIdx = InstFlagIdx + 1;
         Register Def = Inst->getOperand(DefRegIdx).getReg();
 
-        // Copy input to new vreg with same reg class as Def
-        const TargetRegisterClass *RC = MRI->getRegClass(Def);
         ArrayRef<Register> SrcRegs = GetOrCreateVRegs(*OpInfo.CallOperandVal);
         assert(SrcRegs.size() == 1 && "Single register is expected here");
-        Register Tmp = MRI->createVirtualRegister(RC);
-        if (!buildAnyextOrCopy(Tmp, SrcRegs[0], MIRBuilder))
-          return false;
-
-        // Add Flag and input register operand (Tmp) to Inst. Tie Tmp to Def.
+        Register In;
+        // When Def is vreg: copy input to new vreg with same reg class as Def.
+        if (!Def.isPhysical()) {
+          In = MRI->createVirtualRegister(MRI->getRegClass(Def));
+          if (!buildAnyextOrCopy(In, SrcRegs[0], MIRBuilder))
+            return false;
+        } else // When Def is physreg: use given input.
+          In = SrcRegs[0];
+
+        // Add Flag and input register operand (In) to Inst. Tie In to Def.
         unsigned UseFlag = InlineAsm::getFlagWord(InlineAsm::Kind_RegUse, 1);
         unsigned Flag = InlineAsm::getFlagWordForMatchingOp(UseFlag, DefIdx);
         Inst.addImm(Flag);
-        Inst.addReg(Tmp);
+        Inst.addReg(In);
         Inst->tieOperands(DefRegIdx, Inst->getNumOperands() - 1);
         break;
       }


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