LocalCSE: Check effects/generativity early (#6587)

Previously we checked late, and as a result might end up failing to optimize when
a sub-pattern could have worked. E.g.

(call
  (A)
)
(call
  (A)
)

The call cannot be optimized, but the A pattern repeats. Before this PR we'd
greedily focus on the entire call and then fail. After this PR we skip the call
before we commit to which patterns to try to optimize, so we succeed.

Add a isShallowlyGenerative helper here as we compute this step by step as
we go. Also remove a parameter to the generativity code (it did not use the
features it was passed).

1 files changed, 1 insertions, 1 deletions

diff --git a/src/passes/OptimizeInstructions.cpp b/src/passes/OptimizeInstructions.cpp
index 3486fe82a..1a474be2c 100644
--- a/src/passes/OptimizeInstructions.cpp
+++ b/src/passes/OptimizeInstructions.cpp
@@ -2508,7 +2508,7 @@ private:
 
     // To be equal, they must also be known to return the same result
     // deterministically.
-    return !Properties::isGenerative(left, getModule()->features);
+    return !Properties::isGenerative(left);
   }
 
   // Similar to areConsecutiveInputsEqual() but also checks if we can remove