[PATCHv4] powerpc: Automatic CPU detection in preconfigure

[Paul E. Murphy]

Changes for 4;
   * replace broken machine -> mcpu wrapper regex with an
     orthogonal one to unswizzle the machine name.

Changes for 3:
   * change test avoid running on non-ppc machines

Followup from
<https://sourceware.org/pipermail/libc-alpha/2020-May/113765.html>

Changes:
   * Scan for the first instance of .machine or -mcpu= within the
     generated assembly file.
   * Don't try to be smart when guessing.  Only choose valid targets.
   * Don't make any extra noise
   * Remove comment about trying to pretty print an error message, just
     fail in the usual autoconf way.

Followup from <https://sourceware.org/legacy-ml/libc-alpha/2017-02/msg00164.html>

---8<---

Added a check to detect the CPU value in preconfigure, so that glibc is
built with the correct --with-cpu value.  And move existing checks into
preconfigure.ac.

Co-Authored-By: Carlos Eduardo Seo  <cseo@linux.vnet.ibm.com>
Co-Authored-By: Tulio Magno Quites Machado Filho  <tuliom@linux.vnet.ibm.com>
---
 sysdeps/powerpc/preconfigure    | 62 +++++++++++++++++++++++++++++----
 sysdeps/powerpc/preconfigure.ac | 58 ++++++++++++++++++++++++++++++
 2 files changed, 113 insertions(+), 7 deletions(-)
 create mode 100644 sysdeps/powerpc/preconfigure.ac

diff --git a/sysdeps/powerpc/preconfigure b/sysdeps/powerpc/preconfigure
index a0ea745bb4..1a40cb8a7e 100644
--- a/sysdeps/powerpc/preconfigure
+++ b/sysdeps/powerpc/preconfigure
@@ -1,4 +1,5 @@
-# preconfigure fragment for powerpc.
+# This file is generated from configure.ac by Autoconf.  DO NOT EDIT!
+ # Local preconfigure fragment for sysdeps/powerpc
 
 case "$machine" in
 powerpc64le)
@@ -13,12 +14,59 @@ powerpc*)
   case "$host_os" in
     *gnuspe*)
       # SPE support was dropped in glibc 2.30.
-      # We can't use AC_MSG_ERROR here.
-      # The parent script is in the middle of printing the
-      # "checking for sysdeps preconfigure fragments" line.
-      echo >&2
-      echo "Host system type $host is no longer supported." >&2
-      exit 1
+      as_fn_error $? "Host system type $host is no longer supported." "$LINENO" 5
+    ;;
+  esac
+  ;;
+esac
+
+# Lets ask the compiler which Power processor we've got, in case the user did
+# not choose a --with-cpu value.  Scan a trivial generated assembly program
+# and scrape the first
+#   .machine <machine>
+# or
+#   .ascii "-mcpu=<machine>"
+# directive which shows up, and try using it.
+case "${machine}:${submachine}" in
+*powerpc*:)
+  archcpu=`echo "int foo () { return 0; }" \
+	   | $CC $CFLAGS $CPPFLAGS -S -frecord-gcc-switches -xc -o - - \
+	   | grep -E "mcpu=|.machine" -m 1 \
+	   | sed -e "s/.*machine \(.*\)/\1/" -e "s/.*mcpu=\(.*\)\"/\1/"`
+  # Note if you add patterns here you must ensure that an appropriate
+  # directory exists in sysdeps/powerpc.  Likewise, if we find a
+  # cpu, don't let the generic configure append extra compiler options.
+  case "$archcpu" in
+  405fp|440fp|464fp|476fp)
+    submachine=${archcpu%fp}
+    if ${libc_cv_cc_submachine+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  libc_cv_cc_submachine=""
+fi
+
+    ;;
+  405|440|464|476)
+    submachine=${archcpu}
+    if ${libc_cv_cc_submachine+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  libc_cv_cc_submachine=""
+fi
+
+    ;;
+
+  a2|970|power[4-9]|power5x|power6+)
+    submachine=${archcpu}
+    if ${libc_cv_cc_submachine+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  libc_cv_cc_submachine=""
+fi
+
+    ;;
+  *)
+    # We couldn't figure it out, assume none
     ;;
   esac
   ;;
diff --git a/sysdeps/powerpc/preconfigure.ac b/sysdeps/powerpc/preconfigure.ac
new file mode 100644
index 0000000000..ad3e7f9f0d
--- /dev/null
+++ b/sysdeps/powerpc/preconfigure.ac
@@ -0,0 +1,58 @@
+GLIBC_PROVIDES dnl See aclocal.m4 in the top level source directory.
+# Local preconfigure fragment for sysdeps/powerpc
+
+case "$machine" in
+powerpc64le)
+  base_machine=powerpc machine=powerpc/powerpc64/le
+  ;;
+powerpc64*)
+  base_machine=powerpc machine=powerpc/powerpc64/be
+  ;;
+powerpc*)
+  base_machine=powerpc machine=powerpc/powerpc32
+  with_fp_cond="!defined __NO_FPRS__"
+  case "$host_os" in
+    *gnuspe*)
+      # SPE support was dropped in glibc 2.30.
+      AC_MSG_ERROR([Host system type $host is no longer supported.])
+    ;;
+  esac
+  ;;
+esac
+
+# Lets ask the compiler which Power processor we've got, in case the user did
+# not choose a --with-cpu value.  Scan a trivial generated assembly program
+# and scrape the first
+#   .machine <machine>
+# or
+#   .ascii "-mcpu=<machine>"
+# directive which shows up, and try using it.
+case "${machine}:${submachine}" in
+*powerpc*:)
+  archcpu=`echo "int foo () { return 0; }" \
+	   | $CC $CFLAGS $CPPFLAGS -S -frecord-gcc-switches -xc -o - - \
+	   | grep -E "mcpu=|[.]machine" -m 1 \
+	   | sed -e "s/.*machine \(.*\)/\1/" -e "s/.*mcpu=\(.*\)\"/\1/"`
+  # Note if you add patterns here you must ensure that an appropriate
+  # directory exists in sysdeps/powerpc.  Likewise, if we find a
+  # cpu, don't let the generic configure append extra compiler options.
+  case "$archcpu" in
+  405fp|440fp|464fp|476fp)
+    submachine=${archcpu%fp}
+    AC_CACHE_VAL(libc_cv_cc_submachine,libc_cv_cc_submachine="")
+    ;;
+  405|440|464|476)
+    submachine=${archcpu}
+    AC_CACHE_VAL(libc_cv_cc_submachine,libc_cv_cc_submachine="")
+    ;;
+
+  a2|970|power[[4-9]]|power5x|power6+)
+    submachine=${archcpu}
+    AC_CACHE_VAL(libc_cv_cc_submachine,libc_cv_cc_submachine="")
+    ;;
+  *)
+    # We couldn't figure it out, assume none
+    ;;
+  esac
+  ;;
+esac
-- 
2.26.2