[Mesa-dev] [PATCH] gen_matypes: fix cross-compiling with gcc

[Mike Frysinger]

The current gen_matypes logic assumes that the host compiler will produce
information that is useful for the target compiler.  Unfortunately, this
is not the case whenever cross-compiling.

When we detect that we're cross-compiling and using GCC, use the target
compiler to produce assembly from the gen_matypes.c source, then process
it with a shell script to create a usable header.  This is similar to how
the linux kernel creates its asm-offsets.c file.

Signed-off-by: Mike Frysinger <vapier at gentoo.org>
---
Note: please keep me on cc as i'm not subscribed

 configs/autoconf.in        |    2 ++
 configure.ac               |    6 ++++++
 src/mesa/x86/Makefile      |   18 +++++++++++++++---
 src/mesa/x86/gen_matypes.c |   35 +++++++++++++++++++++++++++++------
 4 files changed, 52 insertions(+), 9 deletions(-)

diff --git a/configs/autoconf.in b/configs/autoconf.in
index bb8f2c3..4ad49ea 100644
--- a/configs/autoconf.in
+++ b/configs/autoconf.in
@@ -213,3 +213,5 @@ ifneq ($(LLVM_VERSION),)
 endif
 
 HAVE_XF86VIDMODE = @HAVE_XF86VIDMODE@
+
+GEN_ASM_OFFSETS = @GEN_ASM_OFFSETS@
diff --git a/configure.ac b/configure.ac
index 0e03af7..25c30d9 100644
--- a/configure.ac
+++ b/configure.ac
@@ -106,6 +106,7 @@ AC_MSG_RESULT([$acv_mesa_CLANG])
 
 dnl If we're using GCC, make sure that it is at least version 3.3.0.  Older
 dnl versions are explictly not supported.
+GEN_ASM_OFFSETS=no
 if test "x$GCC" = xyes -a "x$acv_mesa_CLANG" = xno; then
     AC_MSG_CHECKING([whether gcc version is sufficient])
     major=0
@@ -123,7 +124,12 @@ if test "x$GCC" = xyes -a "x$acv_mesa_CLANG" = xno; then
     else
         AC_MSG_RESULT([yes])
     fi
+
+    if test "x$cross_compiling" = xyes; then
+        GEN_ASM_OFFSETS=yes
+    fi
 fi
+AC_SUBST([GEN_ASM_OFFSETS])
 
 
 MKDEP_OPTIONS=-fdepend
diff --git a/src/mesa/x86/Makefile b/src/mesa/x86/Makefile
index 9716dc2..0dba5a2 100644
--- a/src/mesa/x86/Makefile
+++ b/src/mesa/x86/Makefile
@@ -13,8 +13,7 @@ INCLUDE_DIRS = \
 	-I../math \
 	-I../tnl
 
-
-default: gen_matypes matypes.h
+default: matypes.h
 
 clean:
 	-rm -f matypes.h gen_matypes
@@ -24,9 +23,22 @@ gen_matypes: gen_matypes.c
 	$(HOST_CC) $(ARCH_FLAGS) $(INCLUDE_DIRS) $(HOST_CFLAGS) gen_matypes.c -o gen_matypes
 
 # need some special rules here, unfortunately
-matypes.h: ../main/mtypes.h ../tnl/t_context.h gen_matypes
+matypes.h: ../main/mtypes.h ../tnl/t_context.h
+
+ifeq ($(GEN_ASM_OFFSETS),yes)
+
+matypes.h: gen_matypes.c
+	$(CC) $(ARCH_FLAGS) $(INCLUDE_DIRS) $(CFLAGS) gen_matypes.c -DASM_OFFSETS -S -o - | \
+		sed -n '/^->/{s:^->::;/[$$]/{s:^:#define :;s:[$$]::};p}' > $@
+
+else
+
+default: gen_matypes
+matypes.h: gen_matypes
 	./gen_matypes > matypes.h
 
+endif
+
 common_x86_asm.o: matypes.h
 3dnow_normal.o: matypes.h
 3dnow_xform1.o: matypes.h
diff --git a/src/mesa/x86/gen_matypes.c b/src/mesa/x86/gen_matypes.c
index 97f71f9..b359bb8 100644
--- a/src/mesa/x86/gen_matypes.c
+++ b/src/mesa/x86/gen_matypes.c
@@ -52,7 +52,7 @@ do {									\
    printf( "\n" );							\
    printf( "/* ====================================================="	\
 	   "========\n" );						\
-   printf( " * Offsets for %s\n", x );					\
+   printf( " * Offsets for " x "\n" );					\
    printf( " */\n" );							\
    printf( "\n" );							\
 } while (0)
@@ -61,20 +61,43 @@ do {									\
 do {									\
    printf( "\n" );							\
    printf( "/*\n" );							\
-   printf( " * Flags for %s\n", x );					\
+   printf( " * Flags for " x "\n" );					\
    printf( " */\n" );							\
    printf( "\n" );							\
 } while (0)
 
-#define OFFSET( s, t, m )						\
-   printf( "#define %s\t%lu\n", s, (unsigned long) offsetof( t, m ) );
+#ifdef ASM_OFFSETS
 
-#define SIZEOF( s, t )							\
-   printf( "#define %s\t%lu\n", s, (unsigned long) sizeof(t) );
+/*
+ * Format the asm output in a special way that we can manipulate
+ * after the fact and turn into the final header for the target.
+ */
+
+#define DEFINE_UL( s, ul )						\
+   __asm__ __volatile__ ( "\n->" s " %0 " : : "i" (ul) )
+
+#define DEFINE( s, d )							\
+   DEFINE_UL( s, d )
+
+#define printf( x )							\
+   __asm__ __volatile__ ( "\n->" x )
+
+#else
+
+#define DEFINE_UL( s, ul )						\
+   printf( "#define %s\t%lu\n", s, (unsigned long) (ul) );
 
 #define DEFINE( s, d )							\
    printf( "#define %s\t0x%" PRIx64 "\n", s, (uint64_t) d );
 
+#endif
+
+#define OFFSET( s, t, m )						\
+   DEFINE_UL( s, offsetof( t, m ) )
+
+#define SIZEOF( s, t )							\
+   DEFINE_UL( s, sizeof(t) )
+
 
 
 int main( int argc, char **argv )
-- 
1.7.8.4