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, 56 insertions, 2 deletions

diff --git a/Makefile.tpl b/Makefile.tpl
index a280a14..38f0b02 100644
--- a/Makefile.tpl
+++ b/Makefile.tpl
@@ -415,6 +415,45 @@ CXXFLAGS = @CXXFLAGS@
 LIBCXXFLAGS = $(CXXFLAGS) -fno-implicit-templates
 GOCFLAGS = $(CFLAGS)
 
+# Pass additional PGO and LTO compiler options to the PGO build.
+BUILD_CFLAGS = $(PGO_BUILD_CFLAGS) $(PGO_BUILD_LTO_CFLAGS)
+override CFLAGS += $(BUILD_CFLAGS)
+override CXXFLAGS += $(BUILD_CFLAGS)
+
+# Additional PGO and LTO compiler options to generate profiling data
+# for the PGO build.
+PGO_BUILD_GEN_FLAGS_TO_PASS = \
+	PGO_BUILD_CFLAGS="@PGO_BUILD_GEN_CFLAGS@" \
+	PGO_BUILD_LTO_CFLAGS="@PGO_BUILD_LTO_CFLAGS@"
+
+# NB: Filter out any compiler options which may fail PGO training runs.
+PGO_BUILD_TRAINING_CFLAGS:= \
+	$(filter-out -Werror=%,$(CFLAGS))
+PGO_BUILD_TRAINING_CXXFLAGS:=\
+	$(filter-out -Werror=%,$(CXXFLAGS))
+PGO_BUILD_TRAINING_CFLAGS:= \
+	$(filter-out -Wall,$(PGO_BUILD_TRAINING_CFLAGS))
+PGO_BUILD_TRAINING_CXXFLAGS:= \
+	$(filter-out -Wall,$(PGO_BUILD_TRAINING_CXXFLAGS))
+PGO_BUILD_TRAINING_CFLAGS:= \
+	$(filter-out -specs=%,$(PGO_BUILD_TRAINING_CFLAGS))
+PGO_BUILD_TRAINING_CXXFLAGS:= \
+	$(filter-out -specs=%,$(PGO_BUILD_TRAINING_CXXFLAGS))
+PGO_BUILD_TRAINING_FLAGS_TO_PASS = \
+	CFLAGS_FOR_TARGET="$(PGO_BUILD_TRAINING_CFLAGS)" \
+	CXXFLAGS_FOR_TARGET="$(PGO_BUILD_TRAINING_CXXFLAGS)"
+
+# Additional PGO and LTO compiler options to use profiling data for the
+# PGO build.
+PGO_BUILD_USE_FLAGS_TO_PASS = \
+	PGO_BUILD_CFLAGS="@PGO_BUILD_USE_CFLAGS@" \
+	PGO_BUILD_LTO_CFLAGS="@PGO_BUILD_LTO_CFLAGS@"
+
+# PGO training targets for the PGO build.  FIXME: Add gold tests to
+# training.
+PGO-TRAINING-TARGETS = binutils gas gdb ld sim
+PGO_BUILD_TRAINING = $(addprefix maybe-check-,$(PGO-TRAINING-TARGETS))
+
 CREATE_GCOV = create_gcov
 
 TFLAGS =
@@ -719,6 +758,12 @@ configure-target: [+
 
 # The target built for a native non-bootstrap build.
 .PHONY: all
+
+# --enable-pgo-build enables the PGO build.
+# 1. First build with -fprofile-generate.
+# 2. Use "make maybe-check-*" to generate profiling data.
+# 3. Use "make clean" to remove the previous build.
+# 4. Rebuild with -fprofile-use.
 all:
 @if gcc-bootstrap
 	[ -f stage_final ] || echo stage3 > stage_final
@@ -727,7 +772,7 @@ all:
 	$(MAKE) $(RECURSE_FLAGS_TO_PASS) `cat stage_final`-bubble
 @endif gcc-bootstrap
 	@: $(MAKE); $(unstage)
-	@r=`${PWD_COMMAND}`; export r; \
+	+@r=`${PWD_COMMAND}`; export r; \
 	s=`cd $(srcdir); ${PWD_COMMAND}`; export s; \
 @if gcc-bootstrap
 	if [ -f stage_last ]; then \
@@ -735,7 +780,16 @@ all:
 	  $(MAKE) $(TARGET_FLAGS_TO_PASS) all-host all-target; \
 	else \
 @endif gcc-bootstrap
-	  $(MAKE) $(RECURSE_FLAGS_TO_PASS) all-host all-target \
+	  $(MAKE) $(RECURSE_FLAGS_TO_PASS) \
+		$(PGO_BUILD_GEN_FLAGS_TO_PASS) all-host all-target \
+@if pgo-build
+	&& $(MAKE) $(RECURSE_FLAGS_TO_PASS) \
+		$(PGO_BUILD_TRAINING_FLAGS_TO_PASS) \
+		$(PGO_BUILD_TRAINING) \
+	&& $(MAKE) $(RECURSE_FLAGS_TO_PASS) clean \
+	&& $(MAKE) $(RECURSE_FLAGS_TO_PASS) \
+		$(PGO_BUILD_USE_FLAGS_TO_PASS) all-host all-target \
+@endif pgo-build
 @if gcc-bootstrap
 	    ; \
 	fi \