Using the __clang__ ifdef isn't right; one could be using clang for
compiling the mingw-w64 crt for use with binutils ld, which requires
a slightly different setup of __CTOR_LIST__.
Also, to ease interoperability between binutils ld and lld, lld could
potentially start providing the __CTOR_LIST__ symbol, and in that case
we shouldn't be providing it ourselves either.
Signed-off-by: Martin Storsjö <mar...@martin.st>
---
mingw-w64-crt/configure.ac | 38 ++++++++++++++++++++++++++++++++++++++
mingw-w64-crt/crt/crtdll.c | 6 +++++-
mingw-w64-crt/crt/crtexe.c | 6 +++++-
mingw-w64-crt/crt/gccmain.c | 8 +++++++-
4 files changed, 55 insertions(+), 3 deletions(-)
diff --git a/mingw-w64-crt/configure.ac b/mingw-w64-crt/configure.ac
index 6a42109..b235885 100644
--- a/mingw-w64-crt/configure.ac
+++ b/mingw-w64-crt/configure.ac
@@ -301,6 +301,44 @@ AC_ARG_ENABLE([tests-unicode],
AM_CONDITIONAL([ENABLE_TESTS_UNICODE],[test x$enable_tests_unicode = xyes])
AC_MSG_RESULT([$enable_tests_unicode])
+AC_MSG_CHECKING([whether the linker provides __CTOR_LIST__])
+saved_LDFLAGS="$LDFLAGS"
+LDFLAGS="$LDFLAGS -nostdlib"
+# Note that binutils 2.30 is broken with respect to __CTOR_LIST__ (the change
+# was reverted for 2.31); it does provide __CTOR_LIST__ automatically only if
+# necessary. But as long as there's no other definition of it, a fallback
+# __CTOR_LIST__ gets pulled in from libgcc, and this fallback is only a dummy
+# to prevent linker errors (in general) and isn't assigned to the right
+# sections. Therefore, it'd be better to test whether we can/should provide
+# our own __CTOR_LIST__.
+
+# But we can't test whether we can provide our own __CTOR_LIST__ with binutils
+# ld either; even if our test provides its own symbol __CTOR_LIST__, ld will
+# include it but silently use its own provided __CTOR_LIST__ instead, and
+# won't error out. For actual real use, that'd mean a stray broken pointer in
+# the .ctors section.
+
+# This test uses both mainCRTStartup and main functions, to let lld deduce
+# entry point and subsystem automatically without having to manually specify,
+# anything. And as long as main() is provided, we need to implicitly provide
+# __main as well, since the compiler injects a call to it.
+AC_LINK_IFELSE([AC_LANG_SOURCE([[
+#include <stdint.h>
+extern const void * __CTOR_LIST__;
+void __main(void) {
+}
+int main(void) {
+ return (int)(intptr_t)__CTOR_LIST__;
+}
+int mainCRTStartup(void) {
+ return main();
+}
+]])],
+[AC_DEFINE([HAVE_CTOR_LIST],[1],[Whether the linker provides __CTOR_LIST__])
+AC_MSG_RESULT(yes)],
+[AC_MSG_RESULT(no)])
+LDFLAGS="$saved_LDFLAGS"
+
# Checks for libraries.
# Checks for header files.
diff --git a/mingw-w64-crt/crt/crtdll.c b/mingw-w64-crt/crt/crtdll.c
index 5f53602..6187f10 100644
--- a/mingw-w64-crt/crt/crtdll.c
+++ b/mingw-w64-crt/crt/crtdll.c
@@ -10,6 +10,10 @@
#define _DLL
#endif
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
#include <oscalls.h>
#include <internal.h>
#include <stdlib.h>
@@ -40,7 +44,7 @@ extern _CRTALLOC(".CRT$XIZ") _PIFV __xi_z[];
extern _CRTALLOC(".CRT$XCA") _PVFV __xc_a[];
extern _CRTALLOC(".CRT$XCZ") _PVFV __xc_z[];
-#ifdef __clang__
+#ifndef HAVE_CTOR_LIST
__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;
diff --git a/mingw-w64-crt/crt/crtexe.c b/mingw-w64-crt/crt/crtexe.c
index 80e0556..361afd2 100644
--- a/mingw-w64-crt/crt/crtexe.c
+++ b/mingw-w64-crt/crt/crtexe.c
@@ -9,6 +9,10 @@
#define _DLL
#endif
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
#define SPECIAL_CRTEXE
#include <oscalls.h>
@@ -64,7 +68,7 @@ extern _CRTALLOC(".CRT$XIZ") _PIFV __xi_z[];
extern _CRTALLOC(".CRT$XCA") _PVFV __xc_a[];
extern _CRTALLOC(".CRT$XCZ") _PVFV __xc_z[];
-#ifdef __clang__
+#ifndef HAVE_CTOR_LIST
__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;
diff --git a/mingw-w64-crt/crt/gccmain.c b/mingw-w64-crt/crt/gccmain.c
index 54cbf02..030cdce 100644
--- a/mingw-w64-crt/crt/gccmain.c
+++ b/mingw-w64-crt/crt/gccmain.c
@@ -8,6 +8,10 @@
#include <stdlib.h>
#include <setjmp.h>
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
typedef void (*func_ptr) (void);
extern func_ptr __CTOR_LIST__[];
extern func_ptr __DTOR_LIST__[];
@@ -28,7 +32,9 @@ __do_global_dtors (void)
}
}
-#ifdef __clang__
+#ifndef HAVE_CTOR_LIST
+// If the linker didn't provide __CTOR_LIST__, we provided it ourselves,
+// and then we also know we have __CTOR_END__ available.
extern func_ptr __CTOR_END__[];
extern func_ptr __DTOR_END__[];
--
2.7.4
------------------------------------------------------------------------------
Check out the vibrant tech community on one of the world's most
engaging tech sites, Slashdot.org! http://sdm.link/slashdot
_______________________________________________
Mingw-w64-public mailing list
Mingw-w64-public@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/mingw-w64-public
