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utils: Fix segfault in flattencfg

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v2: continue iterating through the rest of the bb
    use for loop

v3: initialize FlattenCFG pass in ScalarOps
    add test

v4: split off initializing flattencfg to a separate patch
    add comment

Signed-off-by: Jan Vesely <jan.vesely@rutgers.edu>

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215574 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Jan Vesely 2014-08-13 20:31:53 +00:00
parent f7a325b3a1
commit d3fa093dc9
2 changed files with 31 additions and 4 deletions
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9
lib/Transforms/Utils/FlattenCFG.cpp
View File

@ -238,9 +238,13 @@ bool FlattenCFGOpt::FlattenParallelAndOr(BasicBlock *BB, IRBuilder<> &Builder,
// Do branch inversion.
BasicBlock *CurrBlock = LastCondBlock;
bool EverChanged = false;
while (1) {
for (;CurrBlock != FirstCondBlock;
CurrBlock = CurrBlock->getSinglePredecessor()) {
BranchInst *BI = dyn_cast<BranchInst>(CurrBlock->getTerminator());
CmpInst *CI = dyn_cast<CmpInst>(BI->getCondition());
if (!CI)
continue;
CmpInst::Predicate Predicate = CI->getPredicate();
// Canonicalize icmp_ne -> icmp_eq, fcmp_one -> fcmp_oeq
if ((Predicate == CmpInst::ICMP_NE) || (Predicate == CmpInst::FCMP_ONE)) {
@ -248,9 +252,6 @@ bool FlattenCFGOpt::FlattenParallelAndOr(BasicBlock *BB, IRBuilder<> &Builder,
BI->swapSuccessors();
EverChanged = true;
}
if (CurrBlock == FirstCondBlock)
break;
CurrBlock = CurrBlock->getSinglePredecessor();
}
return EverChanged;
}

26
test/Transforms/Util/flattencfg.ll Normal file
View File

@ -0,0 +1,26 @@
; RUN: opt -flattencfg -S < %s | FileCheck %s
; This test checks whether the pass completes without a crash.
; The code is not transformed in any way
;
; CHECK-LABEL: @test_not_crash
define void @test_not_crash(i32 %in_a) #0 {
entry:
%cmp0 = icmp eq i32 %in_a, -1
%cmp1 = icmp ne i32 %in_a, 0
%cond0 = and i1 %cmp0, %cmp1
br i1 %cond0, label %b0, label %b1
b0: ; preds = %entry
%cmp2 = icmp eq i32 %in_a, 0
%cmp3 = icmp ne i32 %in_a, 1
%cond1 = or i1 %cmp2, %cmp3
br i1 %cond1, label %exit, label %b1
b1: ; preds = %entry, %b0
br label %exit
exit: ; preds = %entry, %b0, %b1
ret void
}