[llvm-commits] [llvm] r164147 - in /llvm/trunk: lib/Transforms/Scalar/LoopStrengthReduce.cpp test/Transforms/LoopStrengthReduce/2011-10-03-CritEdgeMerge.ll
Andrew Trick
atrick at apple.com
Tue Sep 18 10:51:33 PDT 2012
Author: atrick
Date: Tue Sep 18 12:51:33 2012
New Revision: 164147
URL: http://llvm.org/viewvc/llvm-project?rev=164147&view=rev
Log:
LSR critical edge splitting fix for PR13756.
Modified:
llvm/trunk/lib/Transforms/Scalar/LoopStrengthReduce.cpp
llvm/trunk/test/Transforms/LoopStrengthReduce/2011-10-03-CritEdgeMerge.ll
Modified: llvm/trunk/lib/Transforms/Scalar/LoopStrengthReduce.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/LoopStrengthReduce.cpp?rev=164147&r1=164146&r2=164147&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/LoopStrengthReduce.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/LoopStrengthReduce.cpp Tue Sep 18 12:51:33 2012
@@ -4464,17 +4464,21 @@
SplitLandingPadPredecessors(Parent, BB, "", "", P, NewBBs);
NewBB = NewBBs[0];
}
-
- // If PN is outside of the loop and BB is in the loop, we want to
- // move the block to be immediately before the PHI block, not
- // immediately after BB.
- if (L->contains(BB) && !L->contains(PN))
- NewBB->moveBefore(PN->getParent());
-
- // Splitting the edge can reduce the number of PHI entries we have.
- e = PN->getNumIncomingValues();
- BB = NewBB;
- i = PN->getBasicBlockIndex(BB);
+ // If NewBB==NULL, then SplitCriticalEdge refused to split because all
+ // phi predecessors are identical. The simple thing to do is skip
+ // splitting in this case rather than complicate the API.
+ if (NewBB) {
+ // If PN is outside of the loop and BB is in the loop, we want to
+ // move the block to be immediately before the PHI block, not
+ // immediately after BB.
+ if (L->contains(BB) && !L->contains(PN))
+ NewBB->moveBefore(PN->getParent());
+
+ // Splitting the edge can reduce the number of PHI entries we have.
+ e = PN->getNumIncomingValues();
+ BB = NewBB;
+ i = PN->getBasicBlockIndex(BB);
+ }
}
}
Modified: llvm/trunk/test/Transforms/LoopStrengthReduce/2011-10-03-CritEdgeMerge.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/LoopStrengthReduce/2011-10-03-CritEdgeMerge.ll?rev=164147&r1=164146&r2=164147&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/LoopStrengthReduce/2011-10-03-CritEdgeMerge.ll (original)
+++ llvm/trunk/test/Transforms/LoopStrengthReduce/2011-10-03-CritEdgeMerge.ll Tue Sep 18 12:51:33 2012
@@ -1,15 +1,15 @@
; RUN: opt -loop-reduce -S < %s | FileCheck %s
;
; Test LSR's use of SplitCriticalEdge during phi rewriting.
-; Verify that identical edges are merged. rdar://problem/6453893
target triple = "x86-apple-darwin"
-; CHECK: @test
+; Verify that identical edges are merged. rdar://problem/6453893
+; CHECK: @test1
; CHECK: bb89:
; CHECK: phi i8* [ %lsr.iv.next1, %bbA.bb89_crit_edge ], [ %lsr.iv.next1, %bbB.bb89_crit_edge ]{{$}}
-define i8* @test() {
+define i8* @test1() {
entry:
br label %loop
@@ -41,3 +41,41 @@
exit:
ret i8* %tmp75phi
}
+
+; Handle single-predecessor phis: PR13756
+; CHECK: @test2
+; CHECK: bb89:
+; CHECK: phi i8* [ %lsr.iv.next1, %bbA ], [ %lsr.iv.next1, %bbA ], [ %lsr.iv.next1, %bbA ]{{$}}
+define i8* @test2() {
+entry:
+ br label %loop
+
+loop:
+ %rec = phi i32 [ %next, %loop ], [ 0, %entry ]
+ %next = add i32 %rec, 1
+ %tmp75 = getelementptr i8* null, i32 %next
+ br i1 false, label %loop, label %loopexit
+
+loopexit:
+ br i1 false, label %bbA, label %bbB
+
+bbA:
+ switch i32 0, label %bb89 [
+ i32 47, label %bb89
+ i32 58, label %bb89
+ ]
+
+bbB:
+ switch i8 0, label %exit [
+ i8 47, label %exit
+ i8 58, label %exit
+ ]
+
+bb89:
+ %tmp75phi = phi i8* [ %tmp75, %bbA ], [ %tmp75, %bbA ], [ %tmp75, %bbA ]
+ br label %exit
+
+exit:
+ %result = phi i8* [ %tmp75phi, %bb89 ], [ %tmp75, %bbB ], [ %tmp75, %bbB ], [ %tmp75, %bbB ]
+ ret i8* %result
+}
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