[llvm] [DA] Set Distance to zero when Direction is EQ (PR #147966)

[Michael Kruse via llvm-commits]

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@@ -187,6 +187,18 @@ static void dumpExampleDependence(raw_ostream &OS, DependenceInfo *DA,
           OS << "  da analyze - ";
           if (auto D = DA->depends(&*SrcI, &*DstI,
                                    /*UnderRuntimeAssumptions=*/true)) {
+
+            // Verify that the distance begin zero is equivalent to the
+            // direction being EQ.
+            for (unsigned Level = 1; Level <= D->getLevels(); Level++) {
+              const SCEV *Distance = D->getDistance(Level);
+              bool IsDistanceZero = Distance && Distance->isZero();
+              bool IsDirectionEQ =
+                  D->getDirection(Level) == Dependence::DVEntry::EQ;
+              assert(IsDistanceZero == IsDirectionEQ &&
+                     "Inconsistent distance and direction.");
+            }
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Meinersbur wrote:

It is possible to build a non-assert build with `-DLLVM_ENABLE_DUMP=ON` in which case one would get the same unused-variable warning.

`#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)` is for `void dump()` functions that are normally excluded from non-assert builds, but can be re-added using `LLVM_ENABLE_DUMP`. No `.dump()` function being declared or used here.

https://github.com/llvm/llvm-project/pull/147966