[GDB] Use AC_CHECK_SIZEOF to test for PRFPREGSET_T_BROKEN

[GDB] Use AC_CHECK_SIZEOF to test for PRFPREGSET_T_BROKEN

[Matthew Wahab]

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Hello,

If the GDB configure script finds sys/procfs.h and the prfpregset_t
type, it checks whether prfpregset_t is usable, setting
PRFPREGSET_T_BROKEN if so. It does this using AC_TRY_RUN to test the
value of sizeof(prfregset_t). This doesn't work for cross-compiled
builds so for those PRFPREGSET_T_BROKEN is always set.

This patch replaces the use of AC_TRY_RUN with a test that uses
AC_CHECK_SIZEOF to decide whether to set PRFPREGSET_T_BROKEN. This can
be run for cross-compiled builds.

Tested by cross-compiling for aarch64-none-linux-gnu and recent
glibc and by building with the logic inverted, to check the conditional was
correctly executing. Also by building for native x86_64-none-linux-gnu.

Ok for trunk?
Matthew

gdb/
2016-09-26  Matthew Wahab  <matthew.wahab@arm.com>

	* configure.ac (PRFPREGSET_T_BROKEN): Replace AC_TRY_RUN test with
	AC_CHECK_SIZEOF.
	* configure: Regenerate.


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From 568b341cbf730e0323e4add85003a8ab57fab09d Mon Sep 17 00:00:00 2001
From: Matthew Wahab <matthew.wahab@arm.com>
Date: Tue, 23 Aug 2016 11:03:42 +0100
Subject: [PATCH] [GDB] Use AC_CHECK_SIZEOF to test for PRFPREGSET_T_BROKEN

This patch replaces the use of AC_TRY_RUN with a test that uses
AC_CHECK_SIZEOF to decide whether to set PRFPREGSET_T_BROKEN. This can
be run for cross-compiled builds.

gdb/
2016-09-20  Matthew Wahab  <matthew.wahab@arm.com>

	* configure.ac (PRFPREGSET_T_BROKEN): Replace AC_TRY_RUN test with
	AC_CHECK_SIZEOF.
	* configure: Regenerate.
---
 gdb/configure    | 87 ++++++++++++++++++++++++++++++++++++++++++--------------
 gdb/configure.ac | 19 ++++---------
 2 files changed, 72 insertions(+), 34 deletions(-)

diff --git a/gdb/configure.ac b/gdb/configure.ac
index e451e60..b162d87 100644
--- a/gdb/configure.ac
+++ b/gdb/configure.ac
@@ -1573,21 +1573,14 @@ if test "$ac_cv_header_sys_procfs_h" = yes; then
 
   if test $bfd_cv_have_sys_procfs_type_prfpregset_t = yes; then
     AC_MSG_CHECKING(whether prfpregset_t type is broken)
-    AC_CACHE_VAL(gdb_cv_prfpregset_t_broken,
-      [AC_TRY_RUN([#include <sys/procfs.h>
-       int main ()
-       {
-         if (sizeof (prfpregset_t) == sizeof (void *))
-           return 1;
-         return 0;
-       }],
-       gdb_cv_prfpregset_t_broken=no,
-       gdb_cv_prfpregset_t_broken=yes,
-       gdb_cv_prfpregset_t_broken=yes)])
-    AC_MSG_RESULT($gdb_cv_prfpregset_t_broken)
-    if test $gdb_cv_prfpregset_t_broken = yes; then
+    AC_CHECK_SIZEOF(prfpregset_t, [], [ #include <sys/procfs.h> ])
+    AC_CHECK_SIZEOF(void *)
+    if test "${ac_cv_sizeof_prfpregset_t}" = "${ac_cv_sizeof_void_p}"; then
+      AC_MSG_RESULT(yes)
       AC_DEFINE(PRFPREGSET_T_BROKEN, 1,
       [Define if the prfpregset_t type is broken.])
+    else
+      AC_MSG_RESULT(no)
     fi
   fi
 fi
-- 
2.1.4

Re: [GDB] Use AC_CHECK_SIZEOF to test for PRFPREGSET_T_BROKEN

[Andreas Schwab]

On Sep 28 2016, Matthew Wahab <matthew.wahab@foss.arm.com> wrote:

> diff --git a/gdb/configure.ac b/gdb/configure.ac
> index e451e60..b162d87 100644
> --- a/gdb/configure.ac
> +++ b/gdb/configure.ac
> @@ -1573,21 +1573,14 @@ if test "$ac_cv_header_sys_procfs_h" = yes; then
>  
>    if test $bfd_cv_have_sys_procfs_type_prfpregset_t = yes; then
>      AC_MSG_CHECKING(whether prfpregset_t type is broken)
> -    AC_CACHE_VAL(gdb_cv_prfpregset_t_broken,
> -      [AC_TRY_RUN([#include <sys/procfs.h>
> -       int main ()
> -       {
> -         if (sizeof (prfpregset_t) == sizeof (void *))
> -           return 1;
> -         return 0;
> -       }],
> -       gdb_cv_prfpregset_t_broken=no,
> -       gdb_cv_prfpregset_t_broken=yes,
> -       gdb_cv_prfpregset_t_broken=yes)])
> -    AC_MSG_RESULT($gdb_cv_prfpregset_t_broken)
> -    if test $gdb_cv_prfpregset_t_broken = yes; then
> +    AC_CHECK_SIZEOF(prfpregset_t, [], [ #include <sys/procfs.h> ])
> +    AC_CHECK_SIZEOF(void *)
> +    if test "${ac_cv_sizeof_prfpregset_t}" = "${ac_cv_sizeof_void_p}"; then
> +      AC_MSG_RESULT(yes)
>        AC_DEFINE(PRFPREGSET_T_BROKEN, 1,
>        [Define if the prfpregset_t type is broken.])
> +    else
> +      AC_MSG_RESULT(no)

This mangles the configure output.  The output of the AC_CHECK_SIZEOF
checks occurs in the middle of the output of the prfpregset_t check.
You should not nest configure checks.

Andreas.

-- 
Andreas Schwab, SUSE Labs, schwab@suse.de
GPG Key fingerprint = 0196 BAD8 1CE9 1970 F4BE  1748 E4D4 88E3 0EEA B9D7
"And now for something completely different."