[llvm] [GlobalISel] Use setInstrAndDebugLoc in artifact combines (NFCI) (PR #216424)

[Adrian Prantl via llvm-commits]

https://github.com/adrian-prantl created https://github.com/llvm/llvm-project/pull/216424

This is an opportunistic follow-up to https://github.com/llvm/llvm-project/pull/216411 none of the existing tests are currently affected by this.

The remaining setInstr() call sites in LegalizationArtifactCombiner only move the insert point, leaving whatever DebugLoc the previous combine left in the shared builder. Each replaces MI in place, so MI's location is the one to build with.

Assisted-by: claude

>From 11a4524db925b7b9d3d655bf5491db0c1e31d8df Mon Sep 17 00:00:00 2001
From: Adrian Prantl <aprantl at apple.com>
Date: Fri, 14 Aug 2026 15:05:05 -0700
Subject: [PATCH] [GlobalISel] Use setInstrAndDebugLoc in artifact combines
 (NFCI)

The remaining setInstr() call sites in LegalizationArtifactCombiner only
move the insert point, leaving whatever DebugLoc the previous combine
left in the shared builder. Each replaces MI in place, so MI's location
is the one to build with.

No test changes: instrumenting these eight sites over llvm/test with
X86, ARM, AArch64 and AMDGPU enabled shows the builder's location
already matches MI's on all 67504 invocations, so the two calls are
equivalent here for the in-tree tests. This guards against that
ceasing to hold when combine ordering changes.

Assisted-by: claude
---
 .../GlobalISel/LegalizationArtifactCombiner.h    | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/llvm/include/llvm/CodeGen/GlobalISel/LegalizationArtifactCombiner.h b/llvm/include/llvm/CodeGen/GlobalISel/LegalizationArtifactCombiner.h
index 08e567f2e640a..6be8f3ca0996d 100644
--- a/llvm/include/llvm/CodeGen/GlobalISel/LegalizationArtifactCombiner.h
+++ b/llvm/include/llvm/CodeGen/GlobalISel/LegalizationArtifactCombiner.h
@@ -398,7 +398,7 @@ class LegalizationArtifactCombiner {
 
     if (MachineInstr *DefMI = getOpcodeDef(TargetOpcode::G_IMPLICIT_DEF,
                                            MI.getOperand(1).getReg(), MRI)) {
-      Builder.setInstr(MI);
+      Builder.setInstrAndDebugLoc(MI);
       Register DstReg = MI.getOperand(0).getReg();
       LLT DstTy = MRI.getType(DstReg);
 
@@ -474,7 +474,7 @@ class LegalizationArtifactCombiner {
                     .Action == LegalizeActions::MoreElements)
           return false;
 
-        Builder.setInstr(MI);
+        Builder.setInstrAndDebugLoc(MI);
         auto NewUnmerge = Builder.buildUnmerge(UnmergeTy, CastSrcReg);
 
         for (unsigned I = 0; I != NumDefs; ++I) {
@@ -515,7 +515,7 @@ class LegalizationArtifactCombiner {
         }
 
         // Build new unmerge
-        Builder.setInstr(MI);
+        Builder.setInstrAndDebugLoc(MI);
         Builder.buildUnmerge(DstRegs, CastSrcReg);
         UpdatedDefs.append(DstRegs.begin(), DstRegs.begin() + NewNumDefs);
         markInstAndDefDead(MI, CastMI, DeadInsts);
@@ -1184,7 +1184,7 @@ class LegalizationArtifactCombiner {
       if (NumDefs % NumMergeRegs != 0)
         return false;
 
-      Builder.setInstr(MI);
+      Builder.setInstrAndDebugLoc(MI);
       // Transform to UNMERGEs, for example
       //   %1 = G_MERGE_VALUES %4, %5
       //   %9, %10, %11, %12 = G_UNMERGE_VALUES %1
@@ -1234,7 +1234,7 @@ class LegalizationArtifactCombiner {
       if (ConvertOp != 0 || NumMergeRegs % NumDefs != 0)
         return false;
 
-      Builder.setInstr(MI);
+      Builder.setInstrAndDebugLoc(MI);
       // Transform to MERGEs
       //   %6 = G_MERGE_VALUES %17, %18, %19, %20
       //   %7, %8 = G_UNMERGE_VALUES %6
@@ -1267,7 +1267,7 @@ class LegalizationArtifactCombiner {
       }
 
       if (ConvertOp) {
-        Builder.setInstr(MI);
+        Builder.setInstrAndDebugLoc(MI);
 
         for (unsigned Idx = 0; Idx < NumDefs; ++Idx) {
           Register DefReg = MI.getOperand(Idx).getReg();
@@ -1287,7 +1287,7 @@ class LegalizationArtifactCombiner {
              "Bitcast and the other kinds of conversions should "
              "have happened earlier");
 
-      Builder.setInstr(MI);
+      Builder.setInstrAndDebugLoc(MI);
       for (unsigned Idx = 0; Idx < NumDefs; ++Idx) {
         Register DstReg = MI.getOperand(Idx).getReg();
         Register SrcReg = MergeI->getOperand(Idx + 1).getReg();
@@ -1348,7 +1348,7 @@ class LegalizationArtifactCombiner {
       return false;
 
     // TODO: We could modify MI in place in most cases.
-    Builder.setInstr(MI);
+    Builder.setInstrAndDebugLoc(MI);
     Builder.buildExtract(DstReg, MergeI->getOperand(MergeSrcIdx + 1).getReg(),
                          Offset - MergeSrcIdx * MergeSrcSize);
     UpdatedDefs.push_back(DstReg);