[llvm] r339363 - SCEV should forget all loops containing a deleted block.

[Alina Sbirlea via llvm-commits]

Author: asbirlea
Date: Thu Aug  9 10:53:26 2018
New Revision: 339363

URL: http://llvm.org/viewvc/llvm-project?rev=339363&view=rev
Log:
SCEV should forget all loops containing a deleted block.

Summary:
LoopSimplifyCFG should update ScEv for all loops after a block is deleted.
If the deleted block "Succ" is part of L, then it is part of all parent loops, so forget topmost loop.

Reviewers: greened, mkazantsev, sanjoy

Subscribers: jlebar, javed.absar, uabelho, llvm-commits

Differential Revision: https://reviews.llvm.org/D50422

Added:
    llvm/trunk/test/Transforms/LoopIdiom/scev-invalidation_topmostloop.ll
Modified:
    llvm/trunk/lib/Transforms/Scalar/LoopSimplifyCFG.cpp

Modified: llvm/trunk/lib/Transforms/Scalar/LoopSimplifyCFG.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/LoopSimplifyCFG.cpp?rev=339363&r1=339362&r2=339363&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/LoopSimplifyCFG.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/LoopSimplifyCFG.cpp Thu Aug  9 10:53:26 2018
@@ -61,7 +61,8 @@ static bool simplifyLoopCFG(Loop &L, Dom
     // Merge Succ into Pred and delete it.
     MergeBlockIntoPredecessor(Succ, &DTU, &LI);
 
-    SE.forgetLoop(&L);
+    SE.forgetTopmostLoop(&L);
+
     Changed = true;
   }
 

Added: llvm/trunk/test/Transforms/LoopIdiom/scev-invalidation_topmostloop.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/LoopIdiom/scev-invalidation_topmostloop.ll?rev=339363&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/LoopIdiom/scev-invalidation_topmostloop.ll (added)
+++ llvm/trunk/test/Transforms/LoopIdiom/scev-invalidation_topmostloop.ll Thu Aug  9 10:53:26 2018
@@ -0,0 +1,25 @@
+; RUN: opt -S -indvars -loop-idiom -verify -loop-simplifycfg -loop-idiom < %s | FileCheck %s
+
+target triple = "x86_64-unknown-linux-gnu"
+
+; CHECK-LABEL: @f1()
+; CHECK-NEXT: entry:
+define void @f1() {
+entry:
+  br label %lbl1
+
+lbl1:                                             ; preds = %if.end, %entry
+  br label %for
+
+for:                                              ; preds = %if.end, %lbl1
+  br label %lor.end
+
+lor.end:                                          ; preds = %for
+  br i1 undef, label %for.end, label %if.end
+
+if.end:                                           ; preds = %lor.end
+  br i1 undef, label %lbl1, label %for
+
+for.end:                                          ; preds = %lor.end
+  ret void
+}