[GlobalISel] Preserve original flags of output instructions in matchtable

[Pierre-vh]

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.

[llvmbot]

@llvm/pr-subscribers-llvm-globalisel

Author: Pierre van Houtryve (Pierre-vh)

Changes

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

The reason is that the MatchTableExecutor was overwriting the flags.

---

Full diff: https://github.com/llvm/llvm-project/pull/130937.diff

1 Files Affected:

• (modified) llvm/include/llvm/CodeGen/GlobalISel/GIMatchTableExecutorImpl.h (+1-1)

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)

[llvm-ci]

LLVM Buildbot has detected a new failure on builder arc-builder running on arc-worker while building llvm at step 6 "test-build-unified-tree-check-all".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/3/builds/13054

Here is the relevant piece of the build log for the reference

Step 6 (test-build-unified-tree-check-all) failure: 1200 seconds without output running [b'ninja', b'check-all'], attempting to kill
...
17.720 [1/18/59] Linking CXX executable unittests/MI/MITests
18.007 [1/17/60] Linking CXX executable unittests/Transforms/Vectorize/VectorizeTests
18.205 [1/16/61] Linking CXX executable unittests/tools/llvm-profdata/LLVMProfdataTests
18.400 [1/15/62] Linking CXX executable unittests/ExecutionEngine/MCJIT/MCJITTests
18.838 [1/14/63] Linking CXX executable unittests/IR/IRTests
19.343 [1/13/64] Linking CXX executable unittests/tools/llvm-cfi-verify/CFIVerifyTests
19.351 [1/12/65] Linking CXX executable unittests/Target/TargetMachineCTests
19.690 [1/11/66] Linking CXX executable unittests/Transforms/Coroutines/CoroTests
19.691 [1/10/67] Linking CXX executable unittests/Transforms/Instrumentation/InstrumentationTests
19.758 [1/9/68] Linking CXX executable unittests/Passes/PassBuilderBindings/PassesBindingsTests
command timed out: 1200 seconds without output running [b'ninja', b'check-all'], attempting to kill
process killed by signal 9
program finished with exit code -1
elapsedTime=1220.498659