[PATCH] D43236: [LoopInterchange] Loops with empty dependency matrix are safe.

[Florian Hahn via Phabricator via llvm-commits]

fhahn updated this revision to Diff 135799.
fhahn edited the summary of this revision.
fhahn added a comment.

Ping, rebased diff


https://reviews.llvm.org/D43236

Files:
  lib/Transforms/Scalar/LoopInterchange.cpp
  test/Transforms/LoopInterchange/interchange-no-deps.ll


Index: test/Transforms/LoopInterchange/interchange-no-deps.ll
===================================================================
--- test/Transforms/LoopInterchange/interchange-no-deps.ll
+++ test/Transforms/LoopInterchange/interchange-no-deps.ll
@@ -0,0 +1,44 @@
+; RUN: opt < %s -loop-interchange -simplifycfg -S | FileCheck %s
+
+; no_deps_interchange just access a single nested array and can be interchange.
+define i32 @no_deps_interchange([1024 x i32]* nocapture %Arr, i32 %k) local_unnamed_addr #0 {
+entry:
+  br label %for.body
+
+for.body:                                         ; preds = %entry, %for.cond.cleanup3
+  %indvars.iv19 = phi i64 [ 0, %entry ], [ %indvars.iv.next20, %for.cond.cleanup3 ]
+  br label %for.body4
+
+for.body4:                                        ; preds = %for.body, %for.body4
+  %indvars.iv = phi i64 [ 0, %for.body ], [ %indvars.iv.next, %for.body4 ]
+  %arrayidx6 = getelementptr inbounds [1024 x i32], [1024 x i32]* %Arr, i64 %indvars.iv, i64 %indvars.iv19
+  store i32 0, i32* %arrayidx6, align 4
+  %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
+  %exitcond = icmp ne i64 %indvars.iv.next, 1024
+  br i1 %exitcond, label %for.body4, label %for.cond.cleanup3
+
+for.cond.cleanup3:                                ; preds = %for.body4
+  %indvars.iv.next20 = add nuw nsw i64 %indvars.iv19, 1
+  %exitcond21 = icmp ne i64 %indvars.iv.next20, 1024
+  br i1 %exitcond21, label %for.body, label %for.cond.cleanup
+
+
+for.cond.cleanup:                                 ; preds = %for.cond.cleanup3
+  ret i32 0
+}
+
+; CHECK-LABEL: @no_deps_interchange
+; CHECK-LABEL: entry:
+; CHECK-NEXT: br label %for.body4
+
+; CHECK-LABEL: for.body:                                         ; preds = %for.body4, %for.body
+; CHECK: %indvars.iv19 = phi i64 [ %indvars.iv.next20, %for.body ], [ 0, %for.body4 ]
+; CHECK: br i1 %exitcond21, label %for.body, label %for.body4.split
+
+; CHECK-LABEL: for.body4:                                        ; preds = %entry, %for.body4.split
+; CHECK: %indvars.iv = phi i64 [ %indvars.iv.next, %for.body4.split ], [ 0, %entry ]
+; CHECK: br label %for.body
+
+; CHECK-LABEL: for.body4.split:                                  ; preds = %for.body
+; CHECK: %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
+; CHECK: br i1 %exitcond, label %for.body4, label %for.cond.cleanup
Index: lib/Transforms/Scalar/LoopInterchange.cpp
===================================================================
--- lib/Transforms/Scalar/LoopInterchange.cpp
+++ lib/Transforms/Scalar/LoopInterchange.cpp
@@ -173,9 +173,6 @@
     }
   }
 
-  // We don't have a DepMatrix to check legality return false.
-  if (DepMatrix.empty())
-    return false;
   return true;
 }
 


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