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[JumpThreading] A bug fix for stale loop info after unfold select

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Summary:
The return value of a TryToUnfoldSelect call was not checked, which led to an
incorrectly preserved loop info and some crash.

The original crash was reported on https://reviews.llvm.org/D59514.

Reviewers: davidxl, amehsan

Reviewed By: davidxl

Subscribers: fhahn, brzycki, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D61920

llvm-svn: 360780
This commit is contained in:
Hiroshi Yamauchi 2019-05-15 15:15:16 +00:00
parent 7262d884e7
commit eab7033667
2 changed files with 32 additions and 1 deletions
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3
lib/Transforms/Scalar/JumpThreading.cpp
View File

@ -1174,7 +1174,8 @@ bool JumpThreadingPass::ProcessBlock(BasicBlock *BB) {
}
if (SwitchInst *SI = dyn_cast<SwitchInst>(BB->getTerminator()))
TryToUnfoldSelect(SI, BB);
if (TryToUnfoldSelect(SI, BB))
return true;
// Check for some cases that are worth simplifying. Right now we want to look
// for loads that are used by a switch or by the condition for the branch. If

30
test/Transforms/JumpThreading/stale-loop-info-after-unfold-select.ll Normal file
View File

@ -0,0 +1,30 @@
; RUN: opt -passes='require<loops>,jump-threading,verify<loops>' -S < %s
%"type1" = type { i8 }
%"type2" = type opaque
define dso_local i16* @func2(%"type1"* %this, %"type2"*) {
entry:
br label %while.cond
while.cond: ; preds = %func1.exit, %entry
%month.0 = phi i32 [ undef, %entry ], [ %month.0.be, %func1.exit ]
switch i32 %month.0, label %if.end.i [
i32 4, label %func1.exit
i32 1, label %func1.exit
]
if.end.i: ; preds = %while.cond
br label %func1.exit
func1.exit: ; preds = %if.end.i, %while.cond, %while.cond
%retval.0.i = phi i32 [ 9, %if.end.i ], [ 0, %while.cond ], [ 0, %while.cond ]
%call2 = tail call signext i32 @func3(i32 signext %retval.0.i, i32 signext 1, i32 signext 3)
%cmp = icmp slt i32 %call2, 1
%add = add nsw i32 %call2, 2
%month.0.be = select i1 %cmp, i32 %add, i32 %call2
br label %while.cond
}
declare i32 @func3(i32, i32, i32)