Disable relaxed-simd in differential fuzzing (#10045)

alexcrichton · web-flow · commit d58f1b57db6a · 2025-01-18T03:32:51.000Z
We forgot to do this quite a long time ago but this was always the
intention. Turns out with Pulley now being online the fuzzer quickly
found a difference between Pulley and Cranelift where the native x64
instructions differ from the "deterministic" behavior that Pulley
implements. This difference is expected and allowed though, so don't
fuzz it.
diff --git a/crates/fuzzing/src/generators/config.rs b/crates/fuzzing/src/generators/config.rs
@@ -99,6 +99,10 @@ impl Config {
                 }
             }
         }
+
+        // These instructions are explicitly not expected to be exactly the same
+        // across engines. Don't fuzz them.
+        config.relaxed_simd_enabled = false;
     }
 
     /// Uses this configuration and the supplied source of data to generate

Original file line number	Diff line number	Diff line change
`@@ -99,6 +99,10 @@ impl Config {`
`99`	`99`	`}`
`100`	`100`	`}`
`101`	`101`	`}`
	`102`	`+`
	`103`	`+ // These instructions are explicitly not expected to be exactly the same`
	`104`	`+ // across engines. Don't fuzz them.`
	`105`	`+ config.relaxed_simd_enabled = false;`
`102`	`106`	`}`
`103`	`107`
`104`	`108`	`/// Uses this configuration and the supplied source of data to generate`