Refactor capture tracking (which already had a couple flags for whether returns

and stores capture) to permit the caller to see each capture point and decide
whether to continue looking.

Use this inside memdep to do an analysis that basicaa won't do. This lets us
solve another devirtualization case, fixing PR8908!


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@144580 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 25 insertions, 0 deletions

diff --git a/test/Transforms/GVN/rle.ll b/test/Transforms/GVN/rle.ll
index 2f0d2eb367..47ccd85d48 100644
--- a/test/Transforms/GVN/rle.ll
+++ b/test/Transforms/GVN/rle.ll
@@ -642,3 +642,28 @@ declare void @llvm.memset.p0i8.i64(i8* nocapture, i8, i64, i32, i1) nounwind
 
 declare void @llvm.memcpy.p0i8.p0i8.i64(i8* nocapture, i8* nocapture, i64, i32, i1) nounwind
 
+;;===----------------------------------------------------------------------===;;
+;; Load -> Store dependency which isn't interfered with by a call that happens
+;; before the pointer was captured.
+;;===----------------------------------------------------------------------===;;
+
+%class.X = type { [8 x i8] }
+
+@_ZTV1X = weak_odr constant [5 x i8*] zeroinitializer
+@_ZTV1Y = weak_odr constant [5 x i8*] zeroinitializer
+
+declare void @use()
+declare void @use3(i8***, i8**)
+
+; PR8908
+define void @test_escape1() nounwind {
+  %x = alloca i8**, align 8
+  store i8** getelementptr inbounds ([5 x i8*]* @_ZTV1X, i64 0, i64 2), i8*** %x, align 8
+  call void @use() nounwind
+  %DEAD = load i8*** %x, align 8
+  call void @use3(i8*** %x, i8** %DEAD) nounwind
+  ret void
+; CHECK: test_escape1
+; CHECK-NOT: DEAD
+; CHECK: ret
+}