[llvm] [TableGen][GISel] Fix IMPLICIT_DEF operand being added as a use (PR #121283)

[Sergei Barannikov via llvm-commits]

https://github.com/s-barannikov created https://github.com/llvm/llvm-project/pull/121283

`IMPLICIT_DEF` has one operand that is a def, not a use.

>From 46cf6fc74237696070eb90d48a7c213a2c741e9b Mon Sep 17 00:00:00 2001
From: Sergei Barannikov <barannikov88 at gmail.com>
Date: Sun, 29 Dec 2024 10:07:53 +0300
Subject: [PATCH] [TableGen][GISel] Fix IMPLICIT_DEF operand being added as a
 use

`IMPLICIT_DEF` has one operand that is a def, not a use.
---
 .../GlobalISelEmitter/undef-tied-input.td     | 24 +++++++++++++++++++
 llvm/utils/TableGen/GlobalISelEmitter.cpp     |  2 +-
 2 files changed, 25 insertions(+), 1 deletion(-)
 create mode 100644 llvm/test/TableGen/GlobalISelEmitter/undef-tied-input.td

diff --git a/llvm/test/TableGen/GlobalISelEmitter/undef-tied-input.td b/llvm/test/TableGen/GlobalISelEmitter/undef-tied-input.td
new file mode 100644
index 00000000000000..a2ee3dc311772c
--- /dev/null
+++ b/llvm/test/TableGen/GlobalISelEmitter/undef-tied-input.td
@@ -0,0 +1,24 @@
+// RUN: llvm-tblgen -gen-global-isel -I %p/../../../include -I %p/../Common %s | FileCheck %s
+
+include "llvm/Target/Target.td"
+include "GlobalISelEmitterCommon.td"
+
+def undef_tied : OperandWithDefaultOps<untyped, (ops (i32 undef_tied_input))> {
+  let MIOperandInfo = (ops GPR32:$inactive);
+}
+
+let Constraints = "$opt.inactive = $rd" in
+def I1 : I<(outs GPR32:$rd), (ins GPR32:$rs, undef_tied:$opt),
+           [(set GPR32:$rd, (abs i32:$rs))]>;
+
+// CHECK-LABEL: // (abs:{ *:[i32] } i32:{ *:[i32] }:$rs)  =>  (I1:{ *:[i32] } i32:{ *:[i32] }:$rs)
+// CHECK-NEXT: GIR_MakeTempReg, /*TempRegID*/0, /*TypeID*/GILLT_s32,
+// CHECK-NEXT: GIR_BuildMI, /*InsnID*/1, /*Opcode*/GIMT_Encode2(TargetOpcode::IMPLICIT_DEF),
+// CHECK-NEXT: GIR_AddTempRegister, /*InsnID*/1, /*TempRegID*/0, /*TempRegFlags*/GIMT_Encode2(RegState::Define),
+// CHECK-NEXT: GIR_BuildRootMI, /*Opcode*/GIMT_Encode2(MyTarget::I1),
+// CHECK-NEXT: GIR_RootToRootCopy, /*OpIdx*/0, // DstI[rd]
+// CHECK-NEXT: GIR_RootToRootCopy, /*OpIdx*/1, // rs
+// CHECK-NEXT: GIR_AddSimpleTempRegister, /*InsnID*/0, /*TempRegID*/0,
+// CHECK-NEXT: GIR_RootConstrainSelectedInstOperands,
+// CHECK-NEXT: // GIR_Coverage, 0,
+// CHECK-NEXT: GIR_EraseRootFromParent_Done,
diff --git a/llvm/utils/TableGen/GlobalISelEmitter.cpp b/llvm/utils/TableGen/GlobalISelEmitter.cpp
index f0fb11625883ea..092cdd4ad5b435 100644
--- a/llvm/utils/TableGen/GlobalISelEmitter.cpp
+++ b/llvm/utils/TableGen/GlobalISelEmitter.cpp
@@ -1756,7 +1756,7 @@ Error GlobalISelEmitter::importDefaultOperandRenderers(
             &Target.getInstruction(RK.getDef("IMPLICIT_DEF")));
         BuildMIAction &IDMIBuilder =
             *static_cast<BuildMIAction *>(InsertPt->get());
-        IDMIBuilder.addRenderer<TempRegRenderer>(TempRegID);
+        IDMIBuilder.addRenderer<TempRegRenderer>(TempRegID, /*IsDef=*/true);
         DstMIBuilder.addRenderer<TempRegRenderer>(TempRegID);
       } else {
         DstMIBuilder.addRenderer<AddRegisterRenderer>(Target, Def);