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Fix mergefunc infinite loop

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Self-referential constants containing references to a merged function
no longer cause the MergeFunctions pass to infinite loop. Also adds a
reproduction IR which would otherwise fail, which was isolated from a similar
issue in Chromium.

Author: jrkoenig
Reviewers: nlewycky, jfb
Subscribers: llvm-commits, nlewycky, jfb

Differential Revision: http://reviews.llvm.org/D11208

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@242337 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
JF Bastien 2015-07-15 21:51:33 +00:00
parent a0458b67ae
commit 063eb4e389
2 changed files with 46 additions and 2 deletions
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8
lib/Transforms/IPO/MergeFunctions.cpp
View File

@ -1516,6 +1516,8 @@ void MergeFunctions::remove(Function *F) {
void MergeFunctions::removeUsers(Value *V) {
std::vector<Value *> Worklist;
Worklist.push_back(V);
SmallSet<Value*, 8> Visited;
Visited.insert(V);
while (!Worklist.empty()) {
Value *V = Worklist.back();
Worklist.pop_back();
@ -1526,8 +1528,10 @@ void MergeFunctions::removeUsers(Value *V) {
} else if (isa<GlobalValue>(U)) {
// do nothing
} else if (Constant *C = dyn_cast<Constant>(U)) {
for (User *UU : C->users())
Worklist.push_back(UU);
for (User *UU : C->users()) {
if (!Visited.insert(UU).second)
Worklist.push_back(UU);
}
}
}
}

40
test/Transforms/MergeFunc/self-referential-global.ll Normal file
View File

@ -0,0 +1,40 @@
; RUN: opt -mergefunc -disable-output < %s
; A linked list type and simple payload
%LL = type { %S, %LL* }
%S = type { void (%S*, i32)* }
; Table refers to itself via GEP
@Table = internal global [3 x %LL] [%LL { %S { void (%S*, i32)* @B }, %LL* getelementptr inbounds ([3 x %LL], [3 x %LL]* @Table, i32 0, i32 0) }, %LL { %S { void (%S*, i32)* @A }, %LL* getelementptr inbounds ([3 x %LL], [3 x %LL]* @Table, i32 0, i32 0) }, %LL { %S { void (%S*, i32)* @A }, %LL* getelementptr inbounds ([3 x %LL], [3 x %LL]* @Table, i32 0, i32 0) }], align 16
; The body of this is irrelevant; it is long so that mergefunc doesn't skip it as a small function.
define internal void @A(%S* %self, i32 %a) {
%1 = add i32 %a, 32
%2 = add i32 %1, 32
%3 = add i32 %2, 32
%4 = add i32 %3, 32
%5 = add i32 %4, 32
%6 = add i32 %5, 32
%7 = add i32 %6, 32
%8 = add i32 %7, 32
%9 = add i32 %8, 32
%10 = add i32 %9, 32
%11 = add i32 %10, 32
ret void
}
define internal void @B(%S* %self, i32 %a) {
%1 = add i32 %a, 32
%2 = add i32 %1, 32
%3 = add i32 %2, 32
%4 = add i32 %3, 32
%5 = add i32 %4, 32
%6 = add i32 %5, 32
%7 = add i32 %6, 32
%8 = add i32 %7, 32
%9 = add i32 %8, 32
%10 = add i32 %9, 32
%11 = add i32 %10, 32
ret void
}