On Thu, 2 Aug 2018, Liu Hao wrote:
在 2018-08-02 19:02, Martin Storsjö 写道:
Signed-off-by: Martin Storsjö <mar...@martin.st>
---
mingw-w64-crt/crt/crtdll.c | 2 --
mingw-w64-crt/crt/crtexe.c | 2 --
mingw-w64-crt/crt/gccmain.c | 34 ++++++++--------------------------
3 files changed, 8 insertions(+), 30 deletions(-)
diff --git a/mingw-w64-crt/crt/crtdll.c b/mingw-w64-crt/crt/crtdll.c
index 50a9eb4..af69573 100644
--- a/mingw-w64-crt/crt/crtdll.c
+++ b/mingw-w64-crt/crt/crtdll.c
@@ -40,12 +40,10 @@ extern _CRTALLOC(".CRT$XIZ") _PIFV __xi_z[];
extern _CRTALLOC(".CRT$XCA") _PVFV __xc_a[];
extern _CRTALLOC(".CRT$XCZ") _PVFV __xc_z[];
-#ifdef __clang__
__attribute__ (( __section__ (".ctors"), __used__ , aligned(sizeof(void
*)))) const void * __CTOR_LIST__ = (void *) -1;
__attribute__ (( __section__ (".dtors"), __used__ , aligned(sizeof(void
*)))) const void * __DTOR_LIST__ = (void *) -1;
__attribute__ (( __section__ (".ctors.99999"), __used__ ,
aligned(sizeof(void *)))) const void * __CTOR_END__ = (void *) 0;
__attribute__ (( __section__ (".dtors.99999"), __used__ ,
aligned(sizeof(void *)))) const void * __DTOR_END__ = (void *) 0;
-#endif
Does GNU LD recognize the `.99999` suffix?
The known and working way to sort sections for GNU LD for Windows is
.ctors$aaaa
.ctors$foo
.ctors$zzzz
and such sections are sorted in alphabet order rather than numeric order.
This could explain why these symbols are not emitted for GCC.
Yes, GNU LD supports it - you get similar things emitted by GCC if you
specify a constructor priority.
Case example:
$ cat test.cpp
void other(void);
class Foo {
public:
Foo() {
other();
}
};
Foo foo1 __attribute__((init_priority(101)));
Foo foo2 __attribute__((init_priority(65534)));
$ x86_64-w64-mingw32-g++ -S test.cpp -o - -O2 | grep ctors
.section .ctors.65434,"w"
.section .ctors.00001,"w"
The number after .ctors is 65535 minus the value specified in
init_priority. The values are padded to 5 digits with leading zeros, and
GNU LD sorts them alphabetically when linking, which is equal to numeric
order when it's zero padded.
Since the values are in the range 00000-65535, the sentinel at 99999 will
always be sorted last.
diff --git a/mingw-w64-crt/crt/gccmain.c b/mingw-w64-crt/crt/gccmain.c
index 54cbf02..44ff653 100644
--- a/mingw-w64-crt/crt/gccmain.c
+++ b/mingw-w64-crt/crt/gccmain.c
@@ -23,18 +23,24 @@ __do_global_dtors (void)
while (*p)
{
- (*(p)) ();
+ // If the linker provided its own __DTOR_LIST__ in addition to the
+ // one we provide, we'd end up with the first pointer here being
+ // a (func_ptr)-1 sentinel.
jon_y used to require all comments be C89-ish. I am not totally clear about
the reason. May he elaborate a little.
I can change them to that style if there's a preference for that - I'll
not repost any new version of the patch just for that though.
Just to be safe, I'm amending the patch locally like this as well:
@@ -42,7 +42,8 @@ void __do_global_ctors (void)
// we provide, we'd actually stop at __CTOR_LIST__+1, but that's no problem
// for this function.
while (*p != (func_ptr) -1) {
- (*(p))();
+ if (*p)
+ (*(p))();
p--;
}
That doesn't turn out to be necessary in my testing with GNU LD, but it's
safer that way.
// Martin
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