[WebAssembly][GlobalISel] Fix legalizeCustom return value for Helper.lower()

[tclin914]

Helper.lower() returns a LegalizerHelper::LegalizeResult enum where UnableToLegalize=2, which implicitly converts to true (success). Compare against LegalizerHelper::Legalized instead so that legalization failures are correctly reported.

[llvmbot]

@llvm/pr-subscribers-backend-webassembly

Author: Jim Lin (tclin914)

Changes

Helper.lower() returns a LegalizerHelper::LegalizeResult enum where UnableToLegalize=2, which implicitly converts to true (success). Compare against LegalizerHelper::Legalized instead so that legalization failures are correctly reported.

---

Full diff: https://github.com/llvm/llvm-project/pull/191345.diff

1 Files Affected:

• (modified) llvm/lib/Target/WebAssembly/GISel/WebAssemblyLegalizerInfo.cpp (+1-1)

diff --git a/llvm/lib/Target/WebAssembly/GISel/WebAssemblyLegalizerInfo.cpp b/llvm/lib/Target/WebAssembly/GISel/WebAssemblyLegalizerInfo.cpp
index 293ba88605354..a902fcfea6c38 100644
--- a/llvm/lib/Target/WebAssembly/GISel/WebAssemblyLegalizerInfo.cpp
+++ b/llvm/lib/Target/WebAssembly/GISel/WebAssemblyLegalizerInfo.cpp
@@ -90,7 +90,7 @@ bool WebAssemblyLegalizerInfo::legalizeCustom(
       return true;
     }
 
-    return Helper.lower(MI, 0, DstType);
+    return Helper.lower(MI, 0, DstType) == LegalizerHelper::Legalized;
   }
   default:
     break;

[QuantumSegfault]

Wow! Thanks. How'd you notice?

Also, shouldn't this be != LegalizerHelper::UnableToLegalize. That way we don't return false for AlreadyLegal?

[tclin914]

Wow! Thanks. How'd you notice?

Also, shouldn't this be != LegalizerHelper::UnableToLegalize. That way we don't return false for AlreadyLegal?

Updated to != UnableToLegalize. I've been experimenting with AI-assisted code review on recent commits — it flagged the implicit enum-to-bool conversion here where UnableToLegalize=2 converts to true.