[llvm] [DA] Simplify runtime predicate collection and extend to all dependence tests (PR #157523)

[Sebastian Pop via llvm-commits]

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@@ -4036,6 +4049,12 @@ DependenceInfo::depends(Instruction *Src, Instruction *Dst,
       return nullptr;
   }
 
+  // If runtime assumptions were added but not allowed, return confused
+  // dependence.
+  if (!UnderRuntimeAssumptions && !Assumptions.empty())
+    return std::make_unique<Dependence>(Src, Dst, getNonRedundantAssumptions());
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sebpop wrote:

> I think using assert like UnderRuntimeAssumptions || Assumptions.empty() would be better here. We should not add any runtime assumptions if it's not allowed.

Correct. I changed the condition to an assert.
This change adds early returns when we know there's need for runtime predicates that are not allowed.

I found out that we were recording runtime predicates also for dependence tests that were failing to prove or disprove any dependence. I modified the code to only record runtime predicates when the dependence test succeeds. There is no point in recording predicates that did not help prove the dependence info.

https://github.com/llvm/llvm-project/pull/157523