[llvm] 9d1d80b - DAG: Replace legal type check in EmitCopyFromReg (#177788)

[via llvm-commits]

Author: Matt Arsenault
Date: 2026-03-05T13:08:39+01:00
New Revision: 9d1d80b2efcc2292a985a7cf8ad1124c2853f97e

URL: https://github.com/llvm/llvm-project/commit/9d1d80b2efcc2292a985a7cf8ad1124c2853f97e
DIFF: https://github.com/llvm/llvm-project/commit/9d1d80b2efcc2292a985a7cf8ad1124c2853f97e.diff

LOG: DAG: Replace legal type check in EmitCopyFromReg (#177788)

It doesn't make sense that an illegal type would get here; a
CopyFromReg cannot be illegally typed. The only exception that
was hit here is in a handful of SystemZ inline assembly tests
for i128, which use untyped. They shouldn't; it should treat
v2i64 as legal instead. Just leave the untyped check for now.

Added: 
    

Modified: 
    llvm/lib/CodeGen/SelectionDAG/InstrEmitter.cpp

Removed: 
    


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diff  --git a/llvm/lib/CodeGen/SelectionDAG/InstrEmitter.cpp b/llvm/lib/CodeGen/SelectionDAG/InstrEmitter.cpp
index a404dcc2660be..322766dee5aa9 100644
--- a/llvm/lib/CodeGen/SelectionDAG/InstrEmitter.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/InstrEmitter.cpp
@@ -101,12 +101,13 @@ void InstrEmitter::EmitCopyFromReg(SDValue Op, bool IsClone, Register SrcReg,
   // If the node is only used by a CopyToReg and the dest reg is a vreg, use
   // the CopyToReg'd destination register instead of creating a new vreg.
   bool MatchReg = true;
-  const TargetRegisterClass *UseRC = nullptr;
+
   MVT VT = Op.getSimpleValueType();
 
-  // Stick to the preferred register classes for legal types.
-  if (TLI->isTypeLegal(VT))
-    UseRC = TLI->getRegClassFor(VT, Op->isDivergent());
+  // FIXME: The Untyped check is a workaround for SystemZ i128 inline assembly
+  // using i128, when it should probably be using v2i64.
+  const TargetRegisterClass *UseRC =
+      VT == MVT::Untyped ? nullptr : TLI->getRegClassFor(VT, Op->isDivergent());
 
   for (SDNode *User : Op->users()) {
     bool Match = true;