[Pixman] [PATCH] build: improve control logic for enabling MMI.

[Yin Shiyou]

1. Replace LS_CFLAGS with MMI_CFLAGS to express its intention more accurately.
2. Improve the control logic for enabling MMI.

Three essential conditions for enabling MMI:
1) user have not specify --disable-loongson-mmi.
2) MMI options has been specified by MMI_CFLAGS,CC or compiler's default setting.
3) compiler supports these MMI options.
---
 configure.ac | 67 +++++++++++++++++++++++++++++++++++++++---------------------
 1 file changed, 44 insertions(+), 23 deletions(-)

diff --git a/configure.ac b/configure.ac
index 1ca3974..aaae5ef 100644
--- a/configure.ac
+++ b/configure.ac
@@ -272,16 +272,11 @@ PIXMAN_CHECK_CFLAG([-xldscope=hidden], [dnl
 dnl ===========================================================================
 dnl Check for Loongson Multimedia Instructions
 
-if test "x$LS_CFLAGS" = "x" ; then
-    LS_CFLAGS="-march=loongson2f"
-fi
-
-have_loongson_mmi=no
-AC_MSG_CHECKING(whether to use Loongson MMI assembler)
-
+# check CC default configuration
 xserver_save_CFLAGS=$CFLAGS
-CFLAGS=" $LS_CFLAGS $CFLAGS -I$srcdir"
-AC_LINK_IFELSE([AC_LANG_SOURCE([[
+AC_MSG_CHECKING(whether to enable Loongson MMI)
+
+read -d '' tmp_src_mmi << EOF
 #ifndef __mips_loongson_vector_rev
 #error "Loongson Multimedia Instructions are only available on Loongson"
 #endif
@@ -292,35 +287,61 @@ AC_LINK_IFELSE([AC_LANG_SOURCE([[
 int main () {
     union {
         __m64 v;
-        char c[8];
+        char c[[8]]; // autoconf will strip one pair of [], it is not typo
     } a = { .c = {1, 2, 3, 4, 5, 6, 7, 8} };
     int b = 4;
     __m64 c = _mm_srli_pi16 (a.v, b);
     return 0;
-}]])], have_loongson_mmi=yes)
-CFLAGS=$xserver_save_CFLAGS
+}
+EOF
+read -d '' tmp_src_loongson2f << EOF
+#ifndef _MIPS_ARCH_LOONGSON2F
+#error "Loongson 2F support of CC is not enabled, Please use CFLAGS to enable it"
+#endif
+$tmp_src_mmi
+EOF
+read -d '' tmp_src_loongson3a << EOF
+#if !defined(_MIPS_ARCH_LOONGSON2F) && defined(__mips_loongson_mmi)
+#else
+  #error "Loongson 3A/MMI support of CC is not enabled, Please use CFLAGS to enable it"
+#endif
+$tmp_src_mmi
+EOF
+
+CFLAGS="$xserver_save_CFLAGS $MMI_CFLAGS -I$srcdir"
+AC_LINK_IFELSE([AC_LANG_SOURCE([[$tmp_src_loongson2f]])],cc_enable_mmi_2f=yes)
+AC_LINK_IFELSE([AC_LANG_SOURCE([[$tmp_src_loongson3a]])],cc_enable_mmi_3a=yes)
 
+# user may disable MMI by --disable-loongson-mmi even compiler supports it by default
+# or MMI_CFLAGS for MMI is given
 AC_ARG_ENABLE(loongson-mmi,
    [AC_HELP_STRING([--disable-loongson-mmi],
                    [disable Loongson MMI fast paths])],
    [enable_loongson_mmi=$enableval], [enable_loongson_mmi=auto])
 
-if test $enable_loongson_mmi = no ; then
-   have_loongson_mmi=disabled
+if test x"$enable_loongson_mmi" = xyes && \
+   test x"$cc_enable_mmi_2f" != x"yes" && \
+   test x"$cc_enable_mmi_3a" != x"yes"; then
+    AC_MSG_ERROR([MMI_CFLAGS is required while enable MMI.
+    Try to set MMI_CFLAGS as -march=loongson2f for 2F or -mloongson-mmi for 3A])
 fi
 
-if test $have_loongson_mmi = yes ; then
-   AC_DEFINE(USE_LOONGSON_MMI, 1, [use Loongson Multimedia Instructions])
-else
-   LS_CFLAGS=
+# MMI will be disabled if compiler didn't support it or
+# exact option for compiling it is not specified.
+if test x"$enable_loongson_mmi" != xno && \
+   test x"$cc_enable_mmi_2f" != x"yes" && \
+   test x"$cc_enable_mmi_3a" != x"yes"; then
+    enable_loongson_mmi=no
+    MMI_CFLAGS=""
 fi
 
-AC_MSG_RESULT($have_loongson_mmi)
-if test $enable_loongson_mmi = yes && test $have_loongson_mmi = no ; then
-   AC_MSG_ERROR([Loongson MMI not detected])
+CFLAGS="$xserver_save_CFLAGS $MMI_CFLAGS"
+if test x"$enable_loongson_mmi" != xno; then
+   AC_DEFINE(USE_LOONGSON_MMI, 1, [use Loongson Multimedia Instructions])
 fi
+AC_MSG_RESULT($enable_loongson_mmi)
 
-AM_CONDITIONAL(USE_LOONGSON_MMI, test $have_loongson_mmi = yes)
+AM_CONDITIONAL(USE_LOONGSON_MMI, test x"$enable_loongson_mmi" != xno)
 
 dnl ===========================================================================
 dnl Check for MMX
@@ -531,7 +552,7 @@ case $host_os in
       ;;
 esac
 
-AC_SUBST(LS_CFLAGS)
+AC_SUBST(MMI_CFLAGS)
 AC_SUBST(IWMMXT_CFLAGS)
 AC_SUBST(MMX_CFLAGS)
 AC_SUBST(MMX_LDFLAGS)
-- 
2.1.0