Bug fix in SIMD result detection.

Rationale:
Only 2-way phis are currently used in reductions
to carry SIMD results. Note that this will go away
when we introduce proper SIMD types.

Note:
So far I have not been able to make a small regression
test for this. Any pointers on how to set up a catch phi?

Test: test-art-host,target

Bug: b/77725987
Change-Id: I8f8b2dbec35e906878b7f7ed62690c3234db4211

1 files changed, 4 insertions, 1 deletions

diff --git a/compiler/optimizing/nodes_vector.h b/compiler/optimizing/nodes_vector.h
index 9b114eb1f7..1a484e1944 100644
--- a/compiler/optimizing/nodes_vector.h
+++ b/compiler/optimizing/nodes_vector.h
@@ -171,9 +171,12 @@ class HVecOperation : public HVariableInputSizeInstruction {
     if (instruction->IsVecOperation()) {
       return !instruction->IsVecExtractScalar();  // only scalar returning vec op
     } else if (instruction->IsPhi()) {
+      // Vectorizer only uses Phis in reductions, so checking for a 2-way phi
+      // with a direct vector operand as second argument suffices.
       return
           instruction->GetType() == kSIMDType &&
-          instruction->InputAt(1)->IsVecOperation();  // vectorizer does not go deeper
+          instruction->InputCount() == 2 &&
+          instruction->InputAt(1)->IsVecOperation();
     }
     return false;
   }