[PATCH] D71569: [LoopFusion] Ensure that both loops are guarded or neither are guarded.

[Michael Kruse via Phabricator via llvm-commits]

Meinersbur added a comment.

LGTM. @Whitney?



================
Comment at: llvm/lib/Transforms/Scalar/LoopFuse.cpp:738-739
           // Ensure that FC0 and FC1 have identical guards.
-          // If one (or both) are not guarded, this check is not necessary.
-          if (FC0->GuardBranch && FC1->GuardBranch &&
-              !haveIdenticalGuards(*FC0, *FC1)) {
-            LLVM_DEBUG(dbgs() << "Fusion candidates do not have identical "
-                                 "guards. Not Fusing.\n");
-            reportLoopFusion<OptimizationRemarkMissed>(*FC0, *FC1,
-                                                       NonIdenticalGuards);
-            continue;
-          }
+          if (FC0->GuardBranch || FC1->GuardBranch)
+            if (!haveIdenticalGuards(*FC0, *FC1)) {
+              LLVM_DEBUG(dbgs() << "Fusion candidates do not have identical "
----------------
[style] `(FC0->GuardBranch || FC1->GuardBranch) && !haveIdenticalGuards(*FC0, *FC1)`


================
Comment at: llvm/lib/Transforms/Scalar/LoopFuse.cpp:1069-1070
+    // guard.
+    if (!((FC0.GuardBranch && FC1.GuardBranch) ||
+          (!FC0.GuardBranch && !FC1.GuardBranch)))
+      return false;
----------------
The check can still make sense for defensive programming (or replaced by an assertion).

[style] `!FC0.GuardBranch != !FC1.GuardBranch`


Repository:
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  https://reviews.llvm.org/D71569/new/

https://reviews.llvm.org/D71569