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[ObjCARC] Account for catchswitch in bitcast insertion

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A catchswitch is both a pad and a terminator, meaning it must be the
only non-phi instruction in its basic block. When we're inserting a
bitcast in the incoming basic block for a phi, if that incoming block is
a catchswitch, we should go up the dominator tree to find a valid
insertion point rather than attempting to insert before the catchswitch
(which would result in invalid IR).

Differential Revision: https://reviews.llvm.org/D46412

llvm-svn: 331548
This commit is contained in:
Shoaib Meenai 2018-05-04 19:03:11 +00:00
parent eab596452c
commit e178d6126f
2 changed files with 98 additions and 4 deletions
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21
lib/Transforms/ObjCARC/ObjCARCContract.cpp
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@ -606,14 +606,27 @@ bool ObjCARCContract::runOnFunction(Function &F) {
if (PHINode *PHI = dyn_cast<PHINode>(U.getUser())) {
// For PHI nodes, insert the bitcast in the predecessor block.
unsigned ValNo = PHINode::getIncomingValueNumForOperand(OperandNo);
BasicBlock *BB = PHI->getIncomingBlock(ValNo);
if (Replacement->getType() != UseTy)
Replacement = new BitCastInst(Replacement, UseTy, "", &BB->back());
BasicBlock *IncomingBB = PHI->getIncomingBlock(ValNo);
if (Replacement->getType() != UseTy) {
// A catchswitch is both a pad and a terminator, meaning a basic
// block with a catchswitch has no insertion point. Keep going up
// the dominator tree until we find a non-catchswitch.
BasicBlock *InsertBB = IncomingBB;
while (isa<CatchSwitchInst>(InsertBB->getFirstNonPHI())) {
InsertBB = DT->getNode(InsertBB)->getIDom()->getBlock();
}
assert(DT->dominates(Inst, &InsertBB->back()) &&
"Invalid insertion point for bitcast");
Replacement =
new BitCastInst(Replacement, UseTy, "", &InsertBB->back());
}
// While we're here, rewrite all edges for this PHI, rather
// than just one use at a time, to minimize the number of
// bitcasts we emit.
for (unsigned i = 0, e = PHI->getNumIncomingValues(); i != e; ++i)
if (PHI->getIncomingBlock(i) == BB) {
if (PHI->getIncomingBlock(i) == IncomingBB) {
// Keep the UI iterator valid.
if (UI != UE &&
&PHI->getOperandUse(

81
test/Transforms/ObjCARC/contract-catchswitch.ll Normal file
View File

@ -0,0 +1,81 @@
; RUN: opt -S -objc-arc-contract < %s | FileCheck %s
target datalayout = "e-m:x-p:32:32-i64:64-f80:32-n8:16:32-a:0:32-S32"
target triple = "i686--windows-msvc19.11.0"
%0 = type opaque
declare i32 @__CxxFrameHandler3(...)
declare dllimport void @objc_release(i8*) local_unnamed_addr
declare dllimport i8* @objc_retain(i8* returned) local_unnamed_addr
@p = global i8* null, align 4
declare void @f() local_unnamed_addr
define void @g() local_unnamed_addr personality i8* bitcast (i32 (...)* @__CxxFrameHandler3 to i8*) {
entry:
%tmp = load i8*, i8** @p, align 4
%cast = bitcast i8* %tmp to %0*
%tmp1 = tail call i8* @objc_retain(i8* %tmp) #0
; Split the basic block to ensure bitcast ends up in entry.split.
br label %entry.split
entry.split:
invoke void @f()
to label %invoke.cont unwind label %catch.dispatch
; Dummy nested catchswitch to test looping through the dominator tree.
catch.dispatch:
%tmp2 = catchswitch within none [label %catch] unwind label %catch.dispatch1
catch:
%tmp3 = catchpad within %tmp2 [i8* null, i32 64, i8* null]
catchret from %tmp3 to label %invoke.cont
catch.dispatch1:
%tmp4 = catchswitch within none [label %catch1] unwind label %ehcleanup
catch1:
%tmp5 = catchpad within %tmp4 [i8 *null, i32 64, i8* null]
catchret from %tmp5 to label %invoke.cont
invoke.cont:
%tmp6 = load i8*, i8** @p, align 4
%cast1 = bitcast i8* %tmp6 to %0*
%tmp7 = tail call i8* @objc_retain(i8* %tmp6) #0
call void @objc_release(i8* %tmp) #0, !clang.imprecise_release !0
; Split the basic block to ensure bitcast ends up in invoke.cont.split.
br label %invoke.cont.split
invoke.cont.split:
invoke void @f()
to label %invoke.cont1 unwind label %ehcleanup
invoke.cont1:
ret void
ehcleanup:
%tmp8 = phi %0* [ %cast, %catch.dispatch1 ], [ %cast1, %invoke.cont.split ]
%tmp9 = cleanuppad within none []
%tmp10 = bitcast %0* %tmp8 to i8*
call void @objc_release(i8* %tmp10) #0 [ "funclet"(token %tmp9) ]
cleanupret from %tmp9 unwind to caller
}
; CHECK-LABEL: entry.split:
; CHECK-NEXT: %0 = bitcast i8* %tmp1 to %0*
; CHECK-NEXT: invoke void @f()
; CHECK-NEXT: to label %invoke.cont unwind label %catch.dispatch
; CHECK-LABEL: invoke.cont.split:
; CHECK-NEXT: %1 = bitcast i8* %tmp7 to %0*
; CHECK-NEXT: invoke void @f()
; CHECK-NEXT: to label %invoke.cont1 unwind label %ehcleanup
; CHECK-LABEL: ehcleanup:
; CHECK-NEXT: %tmp8 = phi %0* [ %0, %catch.dispatch1 ], [ %1, %invoke.cont.split ]
attributes #0 = { nounwind }
!0 = !{}