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llvm-6502/test/Transforms/ObjCARC/cfg-hazards.ll
Michael Gottesman 0556900b26 [objc-arc] Do not mismatch up retains inside a for loop with releases outside said for loop in the presense of differing provenance caused by escaping blocks. 
This occurs due to an alloca representing a separate ownership from the
original pointer. Thus consider the following pseudo-IR:

  objc_retain(%a)
  for (...) {
    objc_retain(%a)
    %block <- %a
    F(%block)
    objc_release(%block)
  }
  objc_release(%a)

From the perspective of the optimizer, the %block is a separate
provenance from the original %a. Thus the optimizer pairs up the inner
retain for %a and the outer release from %a, resulting in segfaults.

This is fixed by noting that the signature of a mismatch of
retain/releases inside the for loop is a Use/CanRelease top down with an
None bottom up (since bottom up the Retain-CanRelease-Use-Release
sequence is completed by the inner objc_retain, but top down due to the
differing provenance from the objc_release said sequence is not
completed). In said case in CheckForCFGHazards, we now clear the state
of %a implying that no pairing will occur.

Additionally a test case is included.

rdar://12969722

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@179747 91177308-0d34-0410-b5e6-96231b3b80d8
2013-04-18 05:39:45 +00:00

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; RUN: opt -S -objc-arc < %s | FileCheck %s
; rdar://9503416
; Detect loop boundaries and don't move retains and releases
; across them.
declare void @use_pointer(i8*)
declare i8* @objc_retain(i8*)
declare void @objc_release(i8*)
declare void @callee()
declare void @block_callee(void ()*)
; CHECK: define void @test0(
; CHECK: call i8* @objc_retain(
; CHECK: for.body:
; CHECK-NOT: @objc
; CHECK: for.end:
; CHECK: call void @objc_release(
; CHECK: }
define void @test0(i8* %digits) {
entry:
%tmp1 = call i8* @objc_retain(i8* %digits) nounwind
call void @use_pointer(i8* %digits)
br label %for.body
for.body: ; preds = %for.body, %entry
%upcDigitIndex.01 = phi i64 [ 2, %entry ], [ %inc, %for.body ]
call void @use_pointer(i8* %digits)
%inc = add i64 %upcDigitIndex.01, 1
%cmp = icmp ult i64 %inc, 12
br i1 %cmp, label %for.body, label %for.end
for.end: ; preds = %for.body
call void @objc_release(i8* %digits) nounwind, !clang.imprecise_release !0
ret void
}
; CHECK: define void @test1(
; CHECK: call i8* @objc_retain(
; CHECK: for.body:
; CHECK-NOT: @objc
; CHECK: for.end:
; CHECK: void @objc_release(
; CHECK: }
define void @test1(i8* %digits) {
entry:
%tmp1 = call i8* @objc_retain(i8* %digits) nounwind
br label %for.body
for.body: ; preds = %for.body, %entry
%upcDigitIndex.01 = phi i64 [ 2, %entry ], [ %inc, %for.body ]
call void @use_pointer(i8* %digits)
call void @use_pointer(i8* %digits)
%inc = add i64 %upcDigitIndex.01, 1
%cmp = icmp ult i64 %inc, 12
br i1 %cmp, label %for.body, label %for.end
for.end: ; preds = %for.body
call void @objc_release(i8* %digits) nounwind, !clang.imprecise_release !0
ret void
}
; CHECK: define void @test2(
; CHECK: call i8* @objc_retain(
; CHECK: for.body:
; CHECK-NOT: @objc
; CHECK: for.end:
; CHECK: void @objc_release(
; CHECK: }
define void @test2(i8* %digits) {
entry:
%tmp1 = call i8* @objc_retain(i8* %digits) nounwind
br label %for.body
for.body: ; preds = %for.body, %entry
%upcDigitIndex.01 = phi i64 [ 2, %entry ], [ %inc, %for.body ]
call void @use_pointer(i8* %digits)
%inc = add i64 %upcDigitIndex.01, 1
%cmp = icmp ult i64 %inc, 12
br i1 %cmp, label %for.body, label %for.end
for.end: ; preds = %for.body
call void @use_pointer(i8* %digits)
call void @objc_release(i8* %digits) nounwind, !clang.imprecise_release !0
ret void
}
; Delete nested retain+release pairs around loops.
; CHECK: define void @test3(i8* %a) #0 {
; CHECK-NEXT: entry:
; CHECK-NEXT: tail call i8* @objc_retain(i8* %a) [[NUW:#[0-9]+]]
; CHECK-NEXT: br label %loop
; CHECK-NOT: @objc_
; CHECK: exit:
; CHECK-NEXT: call void @objc_release(i8* %a)
; CHECK-NEXT: ret void
; CHECK-NEXT: }
define void @test3(i8* %a) nounwind {
entry:
%outer = call i8* @objc_retain(i8* %a) nounwind
%inner = call i8* @objc_retain(i8* %a) nounwind
br label %loop
loop:
call void @callee()
store i8 0, i8* %a
br i1 undef, label %loop, label %exit
exit:
call void @objc_release(i8* %a) nounwind
call void @objc_release(i8* %a) nounwind, !clang.imprecise_release !0
ret void
}
; CHECK: define void @test4(i8* %a) #0 {
; CHECK-NEXT: entry:
; CHECK-NEXT: tail call i8* @objc_retain(i8* %a) [[NUW]]
; CHECK-NEXT: br label %loop
; CHECK-NOT: @objc_
; CHECK: exit:
; CHECK-NEXT: call void @objc_release(i8* %a)
; CHECK-NEXT: ret void
; CHECK-NEXT: }
define void @test4(i8* %a) nounwind {
entry:
%outer = call i8* @objc_retain(i8* %a) nounwind
%inner = call i8* @objc_retain(i8* %a) nounwind
br label %loop
loop:
br label %more
more:
call void @callee()
call void @callee()
store i8 0, i8* %a
br i1 undef, label %loop, label %exit
exit:
call void @objc_release(i8* %a) nounwind
call void @objc_release(i8* %a) nounwind, !clang.imprecise_release !0
ret void
}
; CHECK: define void @test5(i8* %a) #0 {
; CHECK-NEXT: entry:
; CHECK-NEXT: tail call i8* @objc_retain(i8* %a) [[NUW]]
; CHECK-NEXT: call void @callee()
; CHECK-NEXT: br label %loop
; CHECK-NOT: @objc_
; CHECK: exit:
; CHECK-NEXT: call void @use_pointer(i8* %a)
; CHECK-NEXT: call void @objc_release(i8* %a)
; CHECK-NEXT: ret void
; CHECK-NEXT: }
define void @test5(i8* %a) nounwind {
entry:
%outer = tail call i8* @objc_retain(i8* %a) nounwind
%inner = tail call i8* @objc_retain(i8* %a) nounwind
call void @callee()
br label %loop
loop:
br i1 undef, label %true, label %more
true:
br label %more
more:
br i1 undef, label %exit, label %loop
exit:
call void @use_pointer(i8* %a)
call void @objc_release(i8* %a) nounwind
call void @objc_release(i8* %a) nounwind, !clang.imprecise_release !0
ret void
}
; CHECK: define void @test6(i8* %a) #0 {
; CHECK-NEXT: entry:
; CHECK-NEXT: tail call i8* @objc_retain(i8* %a) [[NUW]]
; CHECK-NEXT: br label %loop
; CHECK-NOT: @objc_
; CHECK: exit:
; CHECK-NEXT: call void @use_pointer(i8* %a)
; CHECK-NEXT: call void @objc_release(i8* %a)
; CHECK-NEXT: ret void
; CHECK-NEXT: }
define void @test6(i8* %a) nounwind {
entry:
%outer = tail call i8* @objc_retain(i8* %a) nounwind
%inner = tail call i8* @objc_retain(i8* %a) nounwind
br label %loop
loop:
br i1 undef, label %true, label %more
true:
call void @callee()
br label %more
more:
br i1 undef, label %exit, label %loop
exit:
call void @use_pointer(i8* %a)
call void @objc_release(i8* %a) nounwind
call void @objc_release(i8* %a) nounwind, !clang.imprecise_release !0
ret void
}
; CHECK: define void @test7(i8* %a) #0 {
; CHECK-NEXT: entry:
; CHECK-NEXT: tail call i8* @objc_retain(i8* %a) [[NUW]]
; CHECK-NEXT: call void @callee()
; CHECK-NEXT: br label %loop
; CHECK-NOT: @objc_
; CHECK: exit:
; CHECK-NEXT: call void @objc_release(i8* %a)
; CHECK-NEXT: ret void
; CHECK-NEXT: }
define void @test7(i8* %a) nounwind {
entry:
%outer = tail call i8* @objc_retain(i8* %a) nounwind
%inner = tail call i8* @objc_retain(i8* %a) nounwind
call void @callee()
br label %loop
loop:
br i1 undef, label %true, label %more
true:
call void @use_pointer(i8* %a)
br label %more
more:
br i1 undef, label %exit, label %loop
exit:
call void @objc_release(i8* %a) nounwind
call void @objc_release(i8* %a) nounwind, !clang.imprecise_release !0
ret void
}
; CHECK: define void @test8(i8* %a) #0 {
; CHECK-NEXT: entry:
; CHECK-NEXT: tail call i8* @objc_retain(i8* %a) [[NUW]]
; CHECK-NEXT: br label %loop
; CHECK-NOT: @objc_
; CHECK: exit:
; CHECK-NEXT: call void @objc_release(i8* %a)
; CHECK-NEXT: ret void
; CHECK-NEXT: }
define void @test8(i8* %a) nounwind {
entry:
%outer = tail call i8* @objc_retain(i8* %a) nounwind
%inner = tail call i8* @objc_retain(i8* %a) nounwind
br label %loop
loop:
br i1 undef, label %true, label %more
true:
call void @callee()
call void @use_pointer(i8* %a)
br label %more
more:
br i1 undef, label %exit, label %loop
exit:
call void @objc_release(i8* %a) nounwind
call void @objc_release(i8* %a) nounwind, !clang.imprecise_release !0
ret void
}
; CHECK: define void @test9(i8* %a) #0 {
; CHECK-NEXT: entry:
; CHECK-NEXT: br label %loop
; CHECK-NOT: @objc_
; CHECK: exit:
; CHECK-NEXT: ret void
; CHECK-NEXT: }
define void @test9(i8* %a) nounwind {
entry:
%outer = tail call i8* @objc_retain(i8* %a) nounwind
%inner = tail call i8* @objc_retain(i8* %a) nounwind
br label %loop
loop:
br i1 undef, label %true, label %more
true:
call void @use_pointer(i8* %a)
br label %more
more:
br i1 undef, label %exit, label %loop
exit:
call void @objc_release(i8* %a) nounwind
call void @objc_release(i8* %a) nounwind, !clang.imprecise_release !0
ret void
}
; CHECK: define void @test10(i8* %a) #0 {
; CHECK-NEXT: entry:
; CHECK-NEXT: br label %loop
; CHECK-NOT: @objc_
; CHECK: exit:
; CHECK-NEXT: ret void
; CHECK-NEXT: }
define void @test10(i8* %a) nounwind {
entry:
%outer = tail call i8* @objc_retain(i8* %a) nounwind
%inner = tail call i8* @objc_retain(i8* %a) nounwind
br label %loop
loop:
br i1 undef, label %true, label %more
true:
call void @callee()
br label %more
more:
br i1 undef, label %exit, label %loop
exit:
call void @objc_release(i8* %a) nounwind
call void @objc_release(i8* %a) nounwind, !clang.imprecise_release !0
ret void
}
; CHECK: define void @test11(i8* %a) #0 {
; CHECK-NEXT: entry:
; CHECK-NEXT: br label %loop
; CHECK-NOT: @objc_
; CHECK: exit:
; CHECK-NEXT: ret void
; CHECK-NEXT: }
define void @test11(i8* %a) nounwind {
entry:
%outer = tail call i8* @objc_retain(i8* %a) nounwind
%inner = tail call i8* @objc_retain(i8* %a) nounwind
br label %loop
loop:
br i1 undef, label %true, label %more
true:
br label %more
more:
br i1 undef, label %exit, label %loop
exit:
call void @objc_release(i8* %a) nounwind
call void @objc_release(i8* %a) nounwind, !clang.imprecise_release !0
ret void
}
; Don't delete anything if they're not balanced.
; CHECK: define void @test12(i8* %a) #0 {
; CHECK-NEXT: entry:
; CHECK-NEXT: %outer = tail call i8* @objc_retain(i8* %a) [[NUW]]
; CHECK-NEXT: %inner = tail call i8* @objc_retain(i8* %a) [[NUW]]
; CHECK-NEXT: br label %loop
; CHECK-NOT: @objc_
; CHECK: exit:
; CHECK-NEXT: call void @objc_release(i8* %a) [[NUW]]
; CHECK-NEXT: call void @objc_release(i8* %a) [[NUW]], !clang.imprecise_release !0
; CHECK-NEXT: ret void
; CHECK-NEXT: }
define void @test12(i8* %a) nounwind {
entry:
%outer = tail call i8* @objc_retain(i8* %a) nounwind
%inner = tail call i8* @objc_retain(i8* %a) nounwind
br label %loop
loop:
br i1 undef, label %true, label %more
true:
ret void
more:
br i1 undef, label %exit, label %loop
exit:
call void @objc_release(i8* %a) nounwind
call void @objc_release(i8* %a) nounwind, !clang.imprecise_release !0
ret void
}
; Do not improperly pair retains in a for loop with releases outside of a for
; loop when the proper pairing is disguised by a separate provenance represented
; by an alloca.
; rdar://12969722
; CHECK: define void @test13(i8* %a) [[NUW]] {
; CHECK: entry:
; CHECK: tail call i8* @objc_retain(i8* %a) [[NUW]]
; CHECK: loop:
; CHECK: tail call i8* @objc_retain(i8* %a) [[NUW]]
; CHECK: call void @block_callee
; CHECK: call void @objc_release(i8* %reloaded_a) [[NUW]]
; CHECK: exit:
; CHECK: call void @objc_release(i8* %a) [[NUW]]
; CHECK: }
define void @test13(i8* %a) nounwind {
entry:
%block = alloca i8*
%a1 = tail call i8* @objc_retain(i8* %a) nounwind
br label %loop
loop:
%a2 = tail call i8* @objc_retain(i8* %a) nounwind
store i8* %a, i8** %block, align 8
%casted_block = bitcast i8** %block to void ()*
call void @block_callee(void ()* %casted_block)
%reloaded_a = load i8** %block, align 8
call void @objc_release(i8* %reloaded_a) nounwind, !clang.imprecise_release !0
br i1 undef, label %loop, label %exit
exit:
call void @objc_release(i8* %a) nounwind, !clang.imprecise_release !0
ret void
}
; CHECK: attributes [[NUW]] = { nounwind }
!0 = metadata !{}
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