gallium/util: rewrite global constructor system for half floats (GCC/MSVC only!)

NOTE: this commit will cause Gallium to fail to build on any compiler
      except GCC, the Microsoft C compiler and compatible compilers that
      claim to be one of those.

This commit removes the u_gctors.cpp mechanism, in favor of using
compiler-specific syntax to add global constructors from C files.

This solves the problem of u_gctors.o not being pulled from static
libraries and avoids using C++.

However, it needs compiler-specific support for every compiler.

The Microsoft C compiler support has not been tested.

1 files changed, 51 insertions, 0 deletions

diff --git a/src/gallium/auxiliary/util/u_init.h b/src/gallium/auxiliary/util/u_init.h
new file mode 100644
index 0000000000..edbcf2dcb9
--- /dev/null
+++ b/src/gallium/auxiliary/util/u_init.h
@@ -0,0 +1,51 @@
+/*
+ * Copyright 2010 Luca Barbieri
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the
+ * next paragraph) shall be included in all copies or substantial
+ * portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+ * IN NO EVENT SHALL THE COPYRIGHT OWNER(S) AND/OR ITS SUPPLIERS BE
+ * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+ * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ *
+ **************************************************************************/
+
+#ifndef U_INIT_H
+#define U_INIT_H
+
+/* Use UTIL_INIT(f) to have f called at program initialization.
+   Note that it is only guaranteed to be called if any symbol in the
+   .c file it is in sis referenced by the program.
+
+   UTIL_INIT functions are called in arbitrary order.
+*/
+
+#ifdef __cplusplus
+/* use a C++ global constructor */
+#define UTIL_INIT(f) struct f##__gctor_t {f##__gctor_t() {x();}} f##__gctor;
+#elif defined(_MSC_VER)
+/* add a pointer to the section where MSVC stores global constructor pointers */
+/* see http://blogs.msdn.com/vcblog/archive/2006/10/20/crt-initialization.aspx and
+   http://stackoverflow.com/questions/1113409/attribute-constructor-equivalent-in-vc */
+#define UTIL_INIT(f) static void __cdecl f##__init(void) {f();}; __declspec(allocate(".CRT$XCU")) void (__cdecl* f##__xcu)(void) = f##__init;
+#elif defined(__GNUC__)
+#define UTIL_INIT(f) static void f##__init(void) __attribute__((constructor)); static void f##__init(void) {f();}
+#else
+#error Unsupported compiler: please find out how to implement global initializers in C on it
+#endif
+
+#endif
+