llvm/test/Transforms/IndVarSimplify/pr25060.ll
Sanjoy Das da2b817d1a [SCEV] Pick backedge values for phi nodes correctly
Summary:
`getConstantEvolutionLoopExitValue` and `ComputeExitCountExhaustively`
assumed all phi nodes in the loop header have the same order of incoming
values.  This is not correct, and this commit changes
`getConstantEvolutionLoopExitValue` and `ComputeExitCountExhaustively`
to lookup the backedge value of a phi node using the loop's latch block.

Unfortunately, there is still some code duplication
`getConstantEvolutionLoopExitValue` and `ComputeExitCountExhaustively`.
At some point in the future we should extract out a helper class /
method that can evolve constant evolution phi nodes across iterations.

Fixes 25060.  Thanks to Mattias Eriksson for the spot-on analysis!

Depends on D13457.

Reviewers: atrick, hfinkel

Subscribers: materi, llvm-commits

Differential Revision: http://reviews.llvm.org/D13458

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@249712 91177308-0d34-0410-b5e6-96231b3b80d8
2015-10-08 18:28:36 +00:00

38 lines
832 B
LLVM

; RUN: opt -S -indvars < %s | FileCheck %s
define i16 @fn1() {
; CHECK-LABEL: @fn1(
entry:
br label %bb1
bb1:
%i = phi i16 [ 0, %entry ], [ 1, %bb1 ]
%storemerge = phi i16 [ %storemerge2, %bb1 ], [ 0, %entry ]
%storemerge2 = phi i16 [ 10, %entry ], [ 200, %bb1 ]
%tmp10 = icmp eq i16 %i, 1
br i1 %tmp10, label %bb5, label %bb1
bb5:
%storemerge.lcssa = phi i16 [ %storemerge, %bb1 ]
; CHECK: ret i16 10
ret i16 %storemerge.lcssa
}
define i16 @fn2() {
; CHECK-LABEL: @fn2(
entry:
br label %bb1
bb1:
%canary = phi i16 [ 0, %entry ], [ %canary.inc, %bb1 ]
%i = phi i16 [ 0, %entry ], [ %storemerge, %bb1 ]
%storemerge = phi i16 [ 0, %bb1 ], [ 10, %entry ]
%canary.inc = add i16 %canary, 1
%_tmp10 = icmp eq i16 %i, 10
br i1 %_tmp10, label %bb5, label %bb1
bb5:
; CHECK: ret i16 1
ret i16 %canary
}