[llvm] 46739be - [GlobalISel] Preserve original flags of output instructions in matchtable (#130937)

[via llvm-commits]

Author: Pierre van Houtryve
Date: 2025-03-13T11:43:06+01:00
New Revision: 46739be7bcfc2d3eb5c83e589229d27a63978d07

URL: https://github.com/llvm/llvm-project/commit/46739be7bcfc2d3eb5c83e589229d27a63978d07
DIFF: https://github.com/llvm/llvm-project/commit/46739be7bcfc2d3eb5c83e589229d27a63978d07.diff

LOG: [GlobalISel] Preserve original flags of output instructions in matchtable (#130937)

We don't have any combine in trunk that uses output MIFlags when using
MIR patterns, but I tried writing one and noticed that the flags were
lost.

The reason is that the MatchTableExecutor was overwriting the flags.

Added: 
    

Modified: 
    llvm/include/llvm/CodeGen/GlobalISel/GIMatchTableExecutorImpl.h

Removed: 
    


################################################################################
diff  --git a/llvm/include/llvm/CodeGen/GlobalISel/GIMatchTableExecutorImpl.h b/llvm/include/llvm/CodeGen/GlobalISel/GIMatchTableExecutorImpl.h
index 2c57f2b5aa029..654112e86e873 100644
--- a/llvm/include/llvm/CodeGen/GlobalISel/GIMatchTableExecutorImpl.h
+++ b/llvm/include/llvm/CodeGen/GlobalISel/GIMatchTableExecutorImpl.h
@@ -80,7 +80,7 @@ bool GIMatchTableExecutor::executeMatchTable(
     for (auto MIB : OutMIs) {
       // Set the NoFPExcept flag when no original matched instruction could
       // raise an FP exception, but the new instruction potentially might.
-      uint16_t MIBFlags = Flags;
+      uint16_t MIBFlags = Flags | MIB.getInstr()->getFlags();
       if (NoFPException && MIB->mayRaiseFPException())
         MIBFlags |= MachineInstr::NoFPExcept;
       if (Observer)