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llvm-mirror/test/CodeGen/X86/coff-weak.ll
Martin Storsjö 839d814b88 [AsmPrinter] Emit .weak directive for weak linkage on COFF for symbols without a comdat
MC already knows how to emulate the .weak directive (with its ELF
semantics; i.e., an undefined weak symbol resolves to 0, and a defined
weak symbol has lower link precedence than a strong symbol of the same
name) using COFF weak externals. Plumb this through the ASM printer too,
so that definitions marked with __attribute__((weak)) at the language
level (which gets translated to weak linkage at the IR level) have the
corresponding .weak directive emitted. Note that declarations marked
with __attribute__((weak)) at the language level (which translates to
extern_weak at the IR level) already have .weak directives emitted.

Weak*/linkonce* symbols without an associated comdat (in particular, ones
generated with __attribute__((weak)) in C/C++) were earlier emitted as
normal unique globals, as the comdat is required to provide the linkonce
semantics. This change makes sure they are emitted as .weak instead,
allowing other symbols to override them.

Rename the existing coff-weak.ll test to coff-linkonce.ll. I'm not
quite sure what that test covers, since the behavior being tested in it
(the emission of a one_only section) is just a result of passing
-function-sections to llc; the linkonce_odr makes no difference.

Add a new coff-weak.ll which tests the new directive emission.

Based on an previous patch by Shoaib Meenai.

Differential Revision: https://reviews.llvm.org/D44543
2020-03-28 18:48:58 +02:00

51 lines
910 B
LLVM

; RUN: llc -mtriple=i686-windows-msvc -o - %s | FileCheck -check-prefix=X86 %s
; RUN: llc -mtriple=x86_64-windows-msvc -o - %s | FileCheck -check-prefix=X64 %s
; X86: .weak _foo
; X64: .weak foo
define weak void @foo() {
ret void
}
; X86: .weak _bar
; X64: .weak bar
define weak_odr void @bar() {
ret void
}
; X86-NOT: .weak _bar_comdat
; X64-NOT: .weak bar_comdat
$bar_comdat = comdat any
define weak_odr void @bar_comdat() comdat {
ret void
}
; X86: .weak _baz
; X64: .weak baz
define linkonce void @baz() {
ret void
}
; X86-NOT: .weak _baz_comdat
; X64-NOT: .weak baz_comdat
$baz_comdat = comdat any
define linkonce void @baz_comdat() comdat {
ret void
}
; X86: .weak _quux
; X64: .weak quux
define linkonce_odr void @quux() {
ret void
}
; X86-NOT: .weak _quux_comdat
; X64-NOT: .weak quux_comdat
$quux_comdat = comdat any
define linkonce_odr void @quux_comdat() comdat {
ret void
}