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[ObjCARC] Prevent code motion into a catchswitch 

A catchswitch must be the only non-phi instruction in its basic block;
attempting to move a retain or release into a catchswitch basic block
will result in invalid IR. Explicitly mark a CFG hazard in this case to
prevent the code motion.

Differential Revision: https://reviews.llvm.org/D46482

llvm-svn: 332430
This commit is contained in:
Shoaib Meenai 2018-05-16 04:52:18 +00:00
parent b8931c1cf4
commit 074728a2a9
3 changed files with 60 additions and 0 deletions
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1
llvm/lib/Transforms/ObjCARC/ObjCARCOpts.cpp
View File

@ -1592,6 +1592,7 @@ bool ObjCARCOpt::PairUpRetainsAndReleases(
assert(It != Retains.end());
const RRInfo &NewRetainRRI = It->second;
KnownSafeTD &= NewRetainRRI.KnownSafe;
CFGHazardAfflicted |= NewRetainRRI.CFGHazardAfflicted;
for (Instruction *NewRetainRelease : NewRetainRRI.Calls) {
auto Jt = Releases.find(NewRetainRelease);
if (Jt == Releases.end())

5
llvm/lib/Transforms/ObjCARC/PtrState.cpp
View File

@ -268,6 +268,11 @@ void BottomUpPtrState::HandlePotentialUse(BasicBlock *BB, Instruction *Inst,
if (isa<InvokeInst>(Inst)) {
const auto IP = BB->getFirstInsertionPt();
InsertAfter = IP == BB->end() ? std::prev(BB->end()) : IP;
if (isa<CatchSwitchInst>(InsertAfter))
// A catchswitch must be the only non-phi instruction in its basic
// block, so attempting to insert an instruction into such a block would
// produce invalid IR.
SetCFGHazardAfflicted(true);
} else {
InsertAfter = std::next(Inst->getIterator());
}

54
llvm/test/Transforms/ObjCARC/opt-catchswitch.ll Normal file
View File

@ -0,0 +1,54 @@
; RUN: opt -S -objc-arc < %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-msvc"
declare i8* @f(i8*, i8*)
declare i32 @__CxxFrameHandler3(...)
declare dllimport i8* @objc_autoreleaseReturnValue(i8* returned)
declare dllimport i8* @objc_retain(i8* returned)
declare dllimport i8* @objc_retainAutoreleasedReturnValue(i8* returned)
declare dllimport void @objc_release(i8*)
define i8* @g(i8* %p, i8* %q) local_unnamed_addr personality i8* bitcast (i32 (...)* @__CxxFrameHandler3 to i8*) {
entry:
%0 = tail call i8* @objc_retain(i8* %p) #0
%1 = tail call i8* @objc_retain(i8* %q) #0
%call = invoke i8* @f(i8* %p, i8* %q)
to label %invoke.cont unwind label %catch.dispatch, !clang.arc.no_objc_arc_exceptions !0
catch.dispatch:
%2 = catchswitch within none [label %catch] unwind to caller
catch:
%3 = catchpad within %2 [i8* null, i32 64, i8* null]
catchret from %3 to label %cleanup
invoke.cont:
%4 = tail call i8* @objc_retainAutoreleasedReturnValue(i8* %call) #0
br label %cleanup
cleanup:
%retval.0 = phi i8* [ %call, %invoke.cont ], [ null, %catch ]
tail call void @objc_release(i8* %q) #0, !clang.imprecise_release !0
tail call void @objc_release(i8* %p) #0, !clang.imprecise_release !0
%5 = tail call i8* @objc_autoreleaseReturnValue(i8* %retval.0) #0
ret i8* %retval.0
}
; CHECK-LABEL: entry:
; CHECK-NEXT: %0 = tail call i8* @objc_retain(i8* %p) #0
; CHECK-NEXT: %call = invoke i8* @f(i8* %p, i8* %q)
; CHECK-NEXT: to label %invoke.cont unwind label %catch.dispatch
; CHECK-LABEL: catch.dispatch:
; CHECK-NEXT: %1 = catchswitch within none [label %catch] unwind to caller
; CHECK-LABEL: cleanup:
; CHECK: tail call void @objc_release(i8* %p) #0
attributes #0 = { nounwind }
!0 = !{}