Support the PGO build for binutils+gdb

Add the --enable-pgo-build[=lto] configure option.  When binutils+gdb
is not built together with GCC, --enable-pgo-build enables the PGO build:

1. First build with -fprofile-generate.
2. Use "make maybe-check-*" to generate profiling data and pass -i to make
to ignore errors when generating profiling data.
3. Use "make clean" to remove the previous build.
4. Rebuild with -fprofile-use.

With --enable-pgo-build=lto, -flto=jobserver -ffat-lto-objects are used
together with -fprofile-generate and -fprofile-use.  Add '+' to the command
line for recursive make to support -flto=jobserver -ffat-lto-objects.

NB: --enable-pgo-build=lto enables the PGO build with LTO while
--enable-lto enables LTO support in toolchain.

	PR binutils/26766
	* Makefile.tpl (BUILD_CFLAGS): New.
	(CFLAGS): Append $(BUILD_CFLAGS).
	(CXXFLAGS): Likewise.
	(PGO_BUILD_GEN_FLAGS_TO_PASS): New.
	(PGO_BUILD_TRAINING_CFLAGS): Likewise.
	(PGO_BUILD_TRAINING_CXXFLAGS): Likewise.
	(PGO_BUILD_TRAINING_FLAGS_TO_PASS): Likewise.
	(PGO_BUILD_TRAINING_MFLAGS): Likewise.
	(PGO_BUILD_USE_FLAGS_TO_PASS): Likewise.
	(PGO-TRAINING-TARGETS): Likewise.
	(PGO_BUILD_TRAINING): Likewise.
	(all): Add '+' to the command line for recursive make.  Support
	the PGO build.
	* configure.ac: Add --enable-pgo-build[=lto].
	AC_SUBST PGO_BUILD_GEN_CFLAGS, PGO_BUILD_USE_CFLAGS and
	PGO_BUILD_LTO_CFLAGS.  Enable the PGO build in Makefile.
	* Makefile.in: Regenerated.
	* configure: Likewise.

1 files changed, 98 insertions, 2 deletions

diff --git a/configure b/configure
index 4c9297d..a75bc26 100755
--- a/configure
+++ b/configure
@@ -692,6 +692,9 @@ extra_mpc_gmp_configure_flags
 extra_mpfr_configure_flags
 gmpinc
 gmplibs
+PGO_BUILD_LTO_CFLAGS
+PGO_BUILD_USE_CFLAGS
+PGO_BUILD_GEN_CFLAGS
 do_compare
 GNATMAKE
 GNATBIND
@@ -792,6 +795,7 @@ enable_libssp
 enable_libstdcxx
 enable_liboffloadmic
 enable_bootstrap
+enable_pgo_build
 with_mpc
 with_mpc_include
 with_mpc_lib
@@ -1522,6 +1526,8 @@ Optional Features:
   --enable-liboffloadmic=ARG
                           build liboffloadmic [ARG={no,host,target}]
   --enable-bootstrap      enable bootstrapping [yes if native build]
+  --enable-pgo-build[=lto]
+                          enable the PGO build
   --disable-isl-version-check
                           disable check for isl version
   --enable-lto            enable link time optimization support
@@ -5422,6 +5428,91 @@ if test "$enable_bootstrap:$GXX" = "yes:yes"; then
   CXX="$CXX -std=gnu++98"
 fi
 
+# Check whether --enable-pgo-build was given.
+if test "${enable_pgo_build+set}" = set; then :
+  enableval=$enable_pgo_build; enable_pgo_build=$enableval
+else
+  enable_pgo_build=no
+fi
+
+
+# Issue errors and warnings for invalid/strange PGO build combinations.
+case "$have_compiler:$host:$target:$enable_pgo_build" in
+  *:*:*:no) ;;
+
+  # Allow the PGO build only if we aren't building a compiler and
+  # we are in a native configuration.
+  no:$build:$build:yes | no:$build:$build:lto) ;;
+
+  # Disallow the PGO bootstrap if we are building a compiler.
+  yes:*:*:yes | yes:*:*:lto)
+    as_fn_error $? "cannot perform the PGO bootstrap when building a compiler" "$LINENO" 5 ;;
+
+  *)
+    as_fn_error $? "invalid option for --enable-pgo-build" "$LINENO" 5
+    ;;
+esac
+
+if test "$enable_pgo_build" != "no"; then
+  { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether the compiler supports -fprofile-generate" >&5
+$as_echo_n "checking whether the compiler supports -fprofile-generate... " >&6; }
+  old_CFLAGS="$CFLAGS"
+  PGO_BUILD_GEN_CFLAGS="-fprofile-generate"
+  CFLAGS="$CFLAGS $PGO_BUILD_CFLAGS"
+
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+int foo;
+_ACEOF
+if ac_fn_c_try_compile "$LINENO"; then :
+
+else
+  PGO_BUILD_GEN_CFLAGS=
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+  CFLAGS="$old_CFLAGS"
+  if test -n "$PGO_BUILD_GEN_CFLAGS"; then
+    { $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
+$as_echo "yes" >&6; }
+    PGO_BUILD_USE_CFLAGS="-fprofile-use"
+  else
+    { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
+$as_echo "no" >&6; }
+    as_fn_error $? "cannot perform the PGO build without -fprofile-generate" "$LINENO" 5
+  fi
+
+  if test "$enable_pgo_build" = "lto"; then
+    { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether the compiler supports -flto=jobserver -ffat-lto-objects" >&5
+$as_echo_n "checking whether the compiler supports -flto=jobserver -ffat-lto-objects... " >&6; }
+    old_CFLAGS="$CFLAGS"
+    PGO_BUILD_LTO_CFLAGS="-flto=jobserver -ffat-lto-objects"
+    CFLAGS="$CFLAGS $PGO_BUILD_LTO_CFLAGS"
+    cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+int foo;
+_ACEOF
+if ac_fn_c_try_compile "$LINENO"; then :
+
+else
+  PGO_BUILD_LTO_CFLAGS=
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+    CFLAGS="$old_CFLAGS"
+    if test -n "$PGO_BUILD_LTO_CFLAGS"; then
+      { $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
+$as_echo "yes" >&6; }
+    else
+      { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
+$as_echo "no" >&6; }
+      { $as_echo "$as_me:${as_lineno-$LINENO}: WARNING: LTO is disabled for the PGO build" >&5
+$as_echo "$as_me: WARNING: LTO is disabled for the PGO build" >&2;}
+    fi
+  fi
+fi
+
+
+
+
 # Used for setting $lt_cv_objdir
 { $as_echo "$as_me:${as_lineno-$LINENO}: checking for objdir" >&5
 $as_echo_n "checking for objdir... " >&6; }
@@ -5611,8 +5702,7 @@ if test -d ${srcdir}/gcc && test "x$have_gmp" = xno; then
   # Check for the recommended and required versions of GMP.
   { $as_echo "$as_me:${as_lineno-$LINENO}: checking for the correct version of gmp.h" >&5
 $as_echo_n "checking for the correct version of gmp.h... " >&6; }
-
-cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 #include "gmp.h"
 int
@@ -7331,6 +7421,12 @@ extrasub_target="$extrasub_target
 /^@unless /d
 /^@endunless /d"
 
+if test "$enable_pgo_build" != "no"; then
+  extrasub_build="$extrasub_build
+/^@if pgo-build\$/d
+/^@endif pgo-build\$/d"
+fi
+
 # Create the serialization dependencies.  This uses a temporary file.
 
 # Check whether --enable-serial-configure was given.