replica
/
hanchenye-llvm-project
2
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity

[SCEVExpander] Don't break SSA in replaceCongruentIVs 

`SCEVExpander::replaceCongruentIVs` bypasses `hoistIVInc` if both the
original and the isomorphic increments are PHI nodes.  Doing this can
break SSA if the isomorphic increment is not dominated by the original
increment.  Get rid of the bypass, and let `hoistIVInc` do the right
thing.

Fixes PR27232 (compile time crash/hang).

llvm-svn: 269212
This commit is contained in:
Sanjoy Das 2016-05-11 17:41:34 +00:00
parent 787c2460c2
commit abb7b93eb9
2 changed files with 42 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
llvm/lib/Analysis/ScalarEvolutionExpander.cpp
View File

@ -1820,8 +1820,7 @@ unsigned SCEVExpander::replaceCongruentIVs(Loop *L, const DominatorTree *DT,
IsomorphicInc->getType());
if (OrigInc != IsomorphicInc && TruncExpr == SE.getSCEV(IsomorphicInc) &&
SE.LI.replacementPreservesLCSSAForm(IsomorphicInc, OrigInc) &&
((isa<PHINode>(OrigInc) && isa<PHINode>(IsomorphicInc)) ||
hoistIVInc(OrigInc, IsomorphicInc))) {
hoistIVInc(OrigInc, IsomorphicInc)) {
DEBUG_WITH_TYPE(DebugType,
dbgs() << "INDVARS: Eliminated congruent iv.inc: "
<< *IsomorphicInc << '\n');

41
llvm/test/Analysis/ScalarEvolution/expander-replace-congruent-ivs.ll Normal file
View File

@ -0,0 +1,41 @@
; RUN: opt -S -indvars < %s | FileCheck %s
target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-apple-macosx10.11.0"
; SCEVExpander would try to RAUW %val_2 with %c.lcssa, breaking "def
; dominates uses".
define void @pr27232(i32 %val) {
; CHECK-LABEL: @pr27232(
entry:
br i1 undef, label %loop_0.cond, label %for.body.us
for.body.us:
br label %loop_0.cond
loop_0.cond:
%val_2 = phi i32 [ %val, %for.body.us ], [ undef, %entry ]
br i1 true, label %loop_0.ph, label %loop_1.ph
loop_0.ph:
br label %loop_0
loop_1.exit:
br label %loop_1.ph
loop_1.ph:
%c.lcssa = phi i32 [ 0, %loop_0.cond ], [ %val_2, %loop_1.exit ]
br label %loop_1
loop_0:
br i1 undef, label %loop_0, label %loop_1.exit
loop_1:
%d.1 = phi i32 [ %c.lcssa, %loop_1 ], [ %val_2, %loop_1.ph ]
%t.1 = phi i32 [ %val_2, %loop_1 ], [ %c.lcssa, %loop_1.ph ]
br i1 undef, label %leave, label %loop_1
leave:
ret void
}