[1/2] PR 115800: Fix libgfortran build using --with-cpu=power5

Message ID Zo7D92dTJi5MgvVy@cowardly-lion.the-meissners.org
State New
Headers
Series [1/2] PR 115800: Fix libgfortran build using --with-cpu=power5 |

Checks

Context Check Description
linaro-tcwg-bot/tcwg_gcc_build--master-arm success Build passed
linaro-tcwg-bot/tcwg_gcc_build--master-aarch64 success Build passed
linaro-tcwg-bot/tcwg_gcc_check--master-aarch64 success Test passed
linaro-tcwg-bot/tcwg_gcc_check--master-arm success Test passed

Commit Message

Michael Meissner July 10, 2024, 5:25 p.m. UTC
  If you build a little endian compiler and select a default CPU of power5
(i.e. --with-cpu=power5), GCC cannot be built.  The reason is that both the
libgfortran and libstdc++-v3 libraries assume that all little endian powerpc
builds support IEEE 128-bit floating point.

However, if the default cpu does not support the VSX instruction set, then we
cannot build the IEEE 128-bit libraries.  This patch fixes the libgfortran
library so if the GCC compiler does not support IEEE 128-bit floating point, the
IEEE 128-bit floating point libraries are not built.  A companion patch will fix
the libstdc++-v3 library.

I have built these patches on a little endian system, doing both normal builds,
and making a build with a power5 default.  There was no regression in the normal
builds.  I have also built a big endian GCC compiler and there was no regression
there.  Can I check this patch into the trunk?

2024-07-10  Michael Meissner  <meissner@linux.ibm.com>

libgfortran/

	PR target/115800
	* configure.ac (powerpc64le*-linux*): Check to see that the compiler
	uses VSX before enabling IEEE 128-bit support.
	* configure: Regenerate.
	* kinds-override.h (GFC_REAL_17): Add check for __VSX__.
	* libgfortran.h (POWER_IEEE128): Likewise.

---
 libgfortran/configure        | 7 +++++--
 libgfortran/configure.ac     | 3 +++
 libgfortran/kinds-override.h | 2 +-
 libgfortran/libgfortran.h    | 2 +-
 4 files changed, 10 insertions(+), 4 deletions(-)
  

Patch

diff --git a/libgfortran/configure b/libgfortran/configure
index 11a1bc5f070..2708e5c7eca 100755
--- a/libgfortran/configure
+++ b/libgfortran/configure
@@ -5981,6 +5981,9 @@  if test "x$GCC" = "xyes"; then
 #if __SIZEOF_LONG_DOUBLE__ != 16
 			   #error long double is double
 			   #endif
+			   #if !defined(__VSX__)
+			   #error VSX is not available
+			   #endif
 int
 main ()
 {
@@ -12847,7 +12850,7 @@  else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 12850 "configure"
+#line 12853 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -12953,7 +12956,7 @@  else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 12956 "configure"
+#line 12959 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
diff --git a/libgfortran/configure.ac b/libgfortran/configure.ac
index cca1ea0ea97..cfaeb9717ab 100644
--- a/libgfortran/configure.ac
+++ b/libgfortran/configure.ac
@@ -148,6 +148,9 @@  if test "x$GCC" = "xyes"; then
       AC_PREPROC_IFELSE(
         [AC_LANG_PROGRAM([[#if __SIZEOF_LONG_DOUBLE__ != 16
 			   #error long double is double
+			   #endif
+			   #if !defined(__VSX__)
+			   #error VSX is not available
 			   #endif]],
                          [[(void) 0;]])],
         [AM_FCFLAGS="$AM_FCFLAGS -mabi=ibmlongdouble -mno-gnu-attribute";
diff --git a/libgfortran/kinds-override.h b/libgfortran/kinds-override.h
index f6b4956c5ca..51f440e5323 100644
--- a/libgfortran/kinds-override.h
+++ b/libgfortran/kinds-override.h
@@ -30,7 +30,7 @@  see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
 #endif
 
 /* Keep these conditions on one line so grep can filter it out.  */
-#if defined(__powerpc64__)  && __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__  && __SIZEOF_LONG_DOUBLE__ == 16
+#if defined(__powerpc64__)  && __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__  && __SIZEOF_LONG_DOUBLE__ == 16 && defined(__VSX__)
 typedef _Float128 GFC_REAL_17;
 typedef _Complex _Float128 GFC_COMPLEX_17;
 #define HAVE_GFC_REAL_17
diff --git a/libgfortran/libgfortran.h b/libgfortran/libgfortran.h
index 5c59ec26e16..23660335243 100644
--- a/libgfortran/libgfortran.h
+++ b/libgfortran/libgfortran.h
@@ -104,7 +104,7 @@  typedef off_t gfc_offset;
 #endif
 
 #if defined(__powerpc64__) && __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__ \
-    && defined __GLIBC_PREREQ
+    && defined __GLIBC_PREREQ && defined(__VSX__)
 #if __GLIBC_PREREQ (2, 32)
 #define POWER_IEEE128 1
 #endif