[PATCH] D52797: Clear LoopToAliasSetMap when outermost loop is deleted

[Huihui Zhang via Phabricator via llvm-commits]

huihuiz updated this revision to Diff 168062.
huihuiz added a comment.

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Repository:
  rL LLVM

https://reviews.llvm.org/D52797

Files:
  lib/Transforms/Scalar/LICM.cpp
  test/Transforms/LICM/outer-loop-fully-unrolled.ll


Index: test/Transforms/LICM/outer-loop-fully-unrolled.ll
===================================================================
--- /dev/null
+++ test/Transforms/LICM/outer-loop-fully-unrolled.ll
@@ -0,0 +1,46 @@
+; RUN: opt -S -loop-unroll -licm < %s | FileCheck %s
+
+; Check that when the outer most loop is fully unrolled, the alias information
+; saved in the LoopToAliasSetMap is cleared, without triggering an assertion in
+; doFinalizaton().
+
+; CHECK: store double %{{.+}}, double* %{{.+}}
+; CHECK: store double %{{.+}}, double* %{{.+}}
+; CHECK: store double %{{.+}}, double* %{{.+}}
+; CHECK: store double %{{.+}}, double* %{{.+}}
+; CHECK: store double %{{.+}}, double* %{{.+}}
+; CHECK: store double %{{.+}}, double* %{{.+}}
+; CHECK: store double %{{.+}}, double* %{{.+}}
+; CHECK: store double %{{.+}}, double* %{{.+}}
+
+define void @foo(double** %A) {
+entry:
+  br label %for.cond1.preheader
+
+for.cond1.preheader:
+  %i = phi i32 [ 1, %entry ], [ %inc.i, %for.cond.cleanup3 ]
+  %arrayidx1 = getelementptr inbounds double*, double** %A, i32 %i
+  %t0 = load double*, double** %arrayidx1, align 4
+  br label %for.body4
+
+for.cond.cleanup:
+  ret void
+
+for.cond.cleanup3:
+  %inc.i = add nuw nsw i32 %i, 1
+  %exitcond = icmp eq i32 %inc.i, 9
+  br i1 %exitcond, label %for.cond.cleanup, label %for.cond1.preheader
+
+for.body4:
+  %j = phi i32 [ 0, %for.cond1.preheader ], [ %inc.j, %for.body4 ]
+  %arrayidx2 = getelementptr inbounds double*, double** %A, i32 %j
+  %t1 = load double*, double** %arrayidx2, align 4
+  %arrayidx3 = getelementptr inbounds double, double* %t1, i32 %i
+  %t2 = load double, double* %arrayidx3, align 8
+  %arrayidx4 = getelementptr inbounds double, double* %t0, i32 %j
+  store double %t2, double* %arrayidx4, align 8
+  %inc.j = add nuw nsw i32 %j, 1
+  %cmp2 = icmp eq i32 %inc.j, %i
+  br i1 %cmp2, label %for.cond.cleanup3, label %for.body4
+}
+
Index: lib/Transforms/Scalar/LICM.cpp
===================================================================
--- lib/Transforms/Scalar/LICM.cpp
+++ lib/Transforms/Scalar/LICM.cpp
@@ -1596,6 +1596,13 @@
 /// Simple Analysis hook. Delete value L from alias set map.
 ///
 void LegacyLICMPass::deleteAnalysisLoop(Loop *L) {
+  // If the loop being deleted is outermost, or removed from its parent loop,
+  // then the alias information saved by its subloops need to be cleared.
+  // Otherwise, the alias information is cached, later collected and erased
+  // by the nearest outer loop.
+  if (!L->getParentLoop())
+    LICM.getLoopToAliasSetMap().clear();
+
   if (!LICM.getLoopToAliasSetMap().count(L))
     return;
 


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