Attached updated patch.
I was itching to invert the .ctors markers so that I could do while (*p)
instead of while (*p != (func_ptr) -1)
but that would create another binutils breakage so I left it.
Let me know how you all want to proceed :)
On Fri, Aug 18, 2017 at 8:39 PM, David Grayson <[email protected]>
wrote:
> On Fri, Aug 18, 2017 at 12:26 PM, Martin Storsjö <[email protected]> wrote:
> > Yup, that resolves the concern.
> >
> > As long as you just use one or the other of *_LIST__ or *_END__ in each
> > function and use the sentinel values instead of comparing the pointers,
> it
> > should be fine. Otherwise the compiler is free to regard the comparison
> as
> > nonsense.
> >
> > // Martin
>
> I'm not so sure; a normal C struct or array would never have a global
> symbol defined in the middle or at the end, so a smart compiler might
> some day assume that if you take a symbol and decrement it, it's an
> invalid pointer. I don't really want to argue much more than that,
> and I don't have a specific thing to point to in the C standard.
>
> --David
>
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From 32525c92b4c94e404834b680bef4c131b0d10ab6 Mon Sep 17 00:00:00 2001
From: Martell Malone <[email protected]>
Date: Fri, 18 Aug 2017 19:59:20 +0100
Subject: [PATCH] crt: Handle .ctors and .dtors within mingw-w64
When building with clang we currently assume you will be
linking with llvm's lld or a bleeding edge binutils.
In future this will become the default method once
binutils support has settled and bumped a few versions.
diff --git a/mingw-w64-crt/crt/crtdll.c b/mingw-w64-crt/crt/crtdll.c
index 07a18408..85035d49 100644
--- a/mingw-w64-crt/crt/crtdll.c
+++ b/mingw-w64-crt/crt/crtdll.c
@@ -40,6 +40,13 @@ extern _CRTALLOC(".CRT$XIZ") _PIFV __xi_z[];
extern _CRTALLOC(".CRT$XCA") _PVFV __xc_a[];
extern _CRTALLOC(".CRT$XCZ") _PVFV __xc_z[];
+#ifdef __clang__
+__attribute__ (( __section__ (".ctors"), __used__ , aligned(sizeof(void *))))
const void * __CTOR_LIST__ = (void *) -1;
+__attribute__ (( __section__ (".dtors"), __used__ , aligned(sizeof(void *))))
const void * __DTOR_LIST__ = (void *) -1;
+__attribute__ (( __section__ (".ctors$zzz"), __used__ , aligned(sizeof(void
*)))) const void * __CTOR_END__ = (void *) 0;
+__attribute__ (( __section__ (".dtors$zzz"), __used__ , aligned(sizeof(void
*)))) const void * __DTOR_END__ = (void *) 0;
+#endif
+
/* TLS initialization hook. */
extern const PIMAGE_TLS_CALLBACK __dyn_tls_init_callback;
diff --git a/mingw-w64-crt/crt/crtexe.c b/mingw-w64-crt/crt/crtexe.c
index ae37e0fe..e3a84784 100644
--- a/mingw-w64-crt/crt/crtexe.c
+++ b/mingw-w64-crt/crt/crtexe.c
@@ -60,6 +60,13 @@ extern _CRTALLOC(".CRT$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$zzz"), __used__ , aligned(sizeof(void
*)))) const void * __CTOR_END__ = (void *) 0;
+__attribute__ (( __section__ (".dtors$zzz"), __used__ , aligned(sizeof(void
*)))) const void * __DTOR_END__ = (void *) 0;
+#endif
+
/* TLS initialization hook. */
extern const PIMAGE_TLS_CALLBACK __dyn_tls_init_callback;
diff --git a/mingw-w64-crt/crt/gccmain.c b/mingw-w64-crt/crt/gccmain.c
index fc0e3500..7c11386e 100644
--- a/mingw-w64-crt/crt/gccmain.c
+++ b/mingw-w64-crt/crt/gccmain.c
@@ -16,18 +16,32 @@ void __do_global_dtors (void);
void __do_global_ctors (void);
void __main (void);
-void
-__do_global_dtors (void)
+void __do_global_dtors (void)
{
static func_ptr *p = __DTOR_LIST__ + 1;
+ while (*p) {
+ (*(p))();
+ p++;
+ }
+}
- while (*p)
- {
- (*(p)) ();
- p++;
- }
+#ifdef __clang__
+extern func_ptr __CTOR_END__[];
+extern func_ptr __DTOR_END__[];
+
+void __do_global_ctors (void)
+{
+ static func_ptr *p = __CTOR_END__ - 1;
+ while (*p != (func_ptr) -1) {
+ (*(p))();
+ p--;
+ }
+ atexit (__do_global_dtors);
}
+#else
+// old method that iterates the list twice because old linker scripts do not
have __CTOR_END__
+
void
__do_global_ctors (void)
{
@@ -47,6 +61,8 @@ __do_global_ctors (void)
atexit (__do_global_dtors);
}
+#endif
+
static int initialized = 0;
void
--
2.14.1
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