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[Local] Handle terminators with users in removeUnreachableBlocks.

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Terminators like invoke can have users outside the current basic block.
We have to replace those users with undef, before replacing the
terminator.

This fixes a crash exposed by rL373430.

Reviewers: brzycki, asbirlea, davide, spatel

Reviewed By: asbirlea

Differential Revision: https://reviews.llvm.org/D68327

llvm-svn: 373513
This commit is contained in:
Florian Hahn 2019-10-02 19:38:24 +00:00
parent 9a90d3875f
commit 5bb7cdf861
2 changed files with 39 additions and 3 deletions
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10
lib/Transforms/Utils/Local.cpp
View File

@ -2246,9 +2246,13 @@ bool llvm::removeUnreachableBlocks(Function &F, DomTreeUpdater *DTU,
}
BB->dropAllReferences();
if (DTU) {
// Remove the terminator of BB to clear the successor list of BB.
if (BB->getTerminator())
BB->getInstList().pop_back();
Instruction *TI = BB->getTerminator();
assert(TI && "Basic block should have a terminator");
// Terminators like invoke can have users. We have to replace their users,
// before removing them.
if (!TI->use_empty())
TI->replaceAllUsesWith(UndefValue::get(TI->getType()));
TI->eraseFromParent();
new UnreachableInst(BB->getContext(), BB);
assert(succ_empty(BB) && "The successor list of BB isn't empty before "
"applying corresponding DTU updates.");

32
unittests/Transforms/Utils/LocalTest.cpp
View File

@ -867,6 +867,36 @@ TEST(Local, RemoveUnreachableBlocks) {
bb2:
br label %bb1
}
declare i32 @__gxx_personality_v0(...)
define void @invoke_terminator() personality i8* bitcast (i32 (...)* @__gxx_personality_v0 to i8*) {
entry:
br i1 undef, label %invoke.block, label %exit
invoke.block:
%cond = invoke zeroext i1 @invokable()
to label %continue.block unwind label %lpad.block
continue.block:
br i1 %cond, label %if.then, label %if.end
if.then:
unreachable
if.end:
unreachable
lpad.block:
%lp = landingpad { i8*, i32 }
catch i8* null
br label %exit
exit:
ret void
}
declare i1 @invokable()
)");
auto runEager = [&](Function &F, DominatorTree *DT) {
@ -890,12 +920,14 @@ TEST(Local, RemoveUnreachableBlocks) {
runWithDomTree(*M, "br_self_loop", runEager);
runWithDomTree(*M, "br_constant", runEager);
runWithDomTree(*M, "br_loop", runEager);
runWithDomTree(*M, "invoke_terminator", runEager);
// Test removeUnreachableBlocks under Lazy UpdateStrategy.
runWithDomTree(*M, "br_simple", runLazy);
runWithDomTree(*M, "br_self_loop", runLazy);
runWithDomTree(*M, "br_constant", runLazy);
runWithDomTree(*M, "br_loop", runLazy);
runWithDomTree(*M, "invoke_terminator", runLazy);
M = parseIR(C,
R"(