; RUN: opt %s -S -disable-basicaa -cfl-steens-aa -aa-eval -print-all-alias-modref-info 2>&1 | FileCheck %s
;
; Regression: we weren't properly checking constexpr selects.

@g = extern_weak dso_local global i32, align 4
@g2 = extern_weak dso_local global i32, align 4
@g3 = extern_weak dso_local global i32, align 4

; CHECK-LABEL: Function: foo
; CHECK: NoAlias: i32* select (i1 icmp ne (i32* @g, i32* null), i32* @g2, i32* @g3), i32** %a
; CHECK: NoAlias: i32* %b, i32** %a
; CHECK: MayAlias: i32* %b, i32* select (i1 icmp ne (i32* @g, i32* null), i32* @g2, i32* @g3)
; CHECK: NoAlias: i32* @g2, i32** %a
; CHECK: MayAlias: i32* @g2, i32* select (i1 icmp ne (i32* @g, i32* null), i32* @g2, i32* @g3)
; CHECK: MayAlias: i32* %b, i32* @g2
; CHECK: NoAlias: i32* @g3, i32** %a
; CHECK: MayAlias: i32* @g3, i32* select (i1 icmp ne (i32* @g, i32* null), i32* @g2, i32* @g3)
; CHECK: MayAlias: i32* %b, i32* @g3
; CHECK: MayAlias: i32* @g2, i32* @g3

define void @foo() {
entry:
  %a = alloca i32*, align 8
  store i32* select (i1 icmp ne (i32* @g, i32* null), i32* @g2, i32* @g3), i32** %a
  %b = load i32*, i32** %a
  %c = load i32, i32* %b
  %d = load i32, i32* @g2
  %e = load i32, i32* @g3
  ret void
}

Add regression test for r331976
Add regression test for r331976

In general, it's difficult to poke the ConstantExpr code in CFLAA, since
LLVM is so great at eagerly reducing ConstantExprs. :)

Sadly, this only shows a functional difference from before the patch
because CFLAA has some special logic around taking loads of non-pointers
into account. Namely, with the broken select behavior, CFLAA will
completely fail to take note of @g3. Since CFLAA doesn't have any record
about @g3 when we do an alias query for @g3 and %a, it conservatively
answers MayAlias. When we properly take @g3 into account with the new
select logic, we get NoAlias for this query.

I suspect that the aforementioned "special logic" isn't completely
correct, but this test-case should prevent future wonky aliasing results
from appearing for these flavors of ConstantExprs, so I think it's still
worth having.


git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@332017 91177308-0d34-0410-b5e6-96231b3b80d8
