mirror of
https://github.com/RPCS3/llvm-mirror.git
synced 2024-10-22 04:22:57 +02:00
5dcb77e9fb
If a local_unnamed_addr attribute is attached to a global, the address is known to be insignificant within the module. It is distinct from the existing unnamed_addr attribute in that it only describes a local property of the module rather than a global property of the symbol. This attribute is intended to be used by the code generator and LTO to allow the linker to decide whether the global needs to be in the symbol table. It is possible to exclude a global from the symbol table if three things are true: - This attribute is present on every instance of the global (which means that the normal rule that the global must have a unique address can be broken without being observable by the program by performing comparisons against the global's address) - The global has linkonce_odr linkage (which means that each linkage unit must have its own copy of the global if it requires one, and the copy in each linkage unit must be the same) - It is a constant or a function (which means that the program cannot observe that the unique-address rule has been broken by writing to the global) Although this attribute could in principle be computed from the module contents, LTO clients (i.e. linkers) will normally need to be able to compute this property as part of symbol resolution, and it would be inefficient to materialize every module just to compute it. See: http://lists.llvm.org/pipermail/llvm-commits/Week-of-Mon-20160509/356401.html http://lists.llvm.org/pipermail/llvm-commits/Week-of-Mon-20160516/356738.html for earlier discussion. Part of the fix for PR27553. Differential Revision: http://reviews.llvm.org/D20348 llvm-svn: 272709
28 lines
856 B
LLVM
28 lines
856 B
LLVM
; RUN: opt -S -globals-aa -functionattrs < %s | FileCheck %s
|
|
; RUN: opt -S -O3 < %s | FileCheck %s
|
|
|
|
; Apart from checking for the direct cause of the bug, we also check
|
|
; if any problematic aliasing rules have accidentally snuck into -O3.
|
|
;
|
|
; Since the "abc" operand bundle is not a special operand bundle that
|
|
; LLVM knows about, all of the stores and loads in @test below have to
|
|
; stay.
|
|
|
|
declare void @foo() readnone
|
|
|
|
; CHECK-LABEL: define i8* @test(i8* %p)
|
|
; CHECK: %a = alloca i8*, align 8
|
|
; CHECK: store i8* %p, i8** %a, align 8
|
|
; CHECK: call void @foo() [ "abc"(i8** %a) ]
|
|
; CHECK: %reload = load i8*, i8** %a, align 8
|
|
; CHECK: ret i8* %reload
|
|
; CHECK: }
|
|
|
|
define i8* @test(i8* %p) {
|
|
%a = alloca i8*, align 8
|
|
store i8* %p, i8** %a, align 8
|
|
call void @foo() ["abc" (i8** %a)]
|
|
%reload = load i8*, i8** %a, align 8
|
|
ret i8* %reload
|
|
}
|