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

[Huihui Zhang via Phabricator via llvm-commits]

huihuiz updated this revision to Diff 168055.
huihuiz edited the summary of this revision.
huihuiz added a comment.

Clear the LoopToAliasSetMap only when the loop being deleted is outermost loop.
Otherwise, the alias information saved by its subloops is cached, and later collected
and erased by their nearest outer loop.


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 +1596,12 @@
 /// Simple Analysis hook. Delete value L from alias set map.
 ///
 void LegacyLICMPass::deleteAnalysisLoop(Loop *L) {
+  // If the loop being deleted is outermost 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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