From 8c8467e3ad26932aaacfb01efb2118d986e5200f Mon Sep 17 00:00:00 2001
From: Lukas Larsson <lukas@erlang.org>
Date: Wed, 25 Oct 2017 10:04:25 +0200
Subject: erts: Only do PGO if gcc supports -fprofile-correction

---
 erts/configure.in         | 18 +++++++-----------
 erts/emulator/Makefile.in | 10 +---------
 2 files changed, 8 insertions(+), 20 deletions(-)

(limited to 'erts')

diff --git a/erts/configure.in b/erts/configure.in
index 9948e71b2d..b47d94b285 100644
--- a/erts/configure.in
+++ b/erts/configure.in
@@ -603,6 +603,8 @@ AS_HELP_STRING([--enable-pgo],
   esac
 ],enable_pgo=default)
 
+LM_CHECK_ENABLE_CFLAG([-fprofile-use -fprofile-correction -Werror],[PROFILE_CORRECTION])
+
 USE_PGO=false
 AC_MSG_CHECKING([whether to do PGO of erts])
 if test $enable_pgo = no; then
@@ -615,22 +617,16 @@ elif test $CROSS_COMPILING = yes; then
   fi
 elif test "X$host" = "Xwin32"; then
   AC_MSG_RESULT([no, not supported in windows])
-elif test "X$PROFILE_GENERATE" = "Xtrue" -a "X$PROFILE_USE" = "Xtrue"; then
+elif test "X$PROFILE_GENERATE" = "Xtrue" -a "X$PROFILE_USE" = "Xtrue" -a "X$PROFILE_CORRECTION" = "Xtrue"; then
+  ## We need -fprofile-generate and -fprofile-correction support to use PGO with
+  ## gcc as multiple threads run within the executed object files
   USE_PGO=true
-  AC_MSG_RESULT([yes, using -fprofile-generate])
   PROFILE_COMPILER=gcc
-# check if $CC accepts -fprofile-correction, if so we can use PGO on multi-threaded files.
-  LM_CHECK_ENABLE_CFLAG([-fprofile-use -fprofile-correction -Werror],[PROFILE_CORRECTION])
-  if test "X$PROFILE_CORRECTION" = "Xtrue"; then
-    PROFILE_CORRECTION="-fprofile-correction"
-  else
-    PROFILE_CORRECTION=""
-  fi
-  AC_SUBST(PROFILE_CORRECTION)
+  AC_MSG_RESULT([yes, using -fprofile-generate -fprofile-correction])
 elif test "X$PROFILE_INSTR_GENERATE" = "Xtrue" -a "X$PROFILE_INSTR_USE" = "Xtrue"; then
   USE_PGO=true
-  AC_MSG_RESULT([yes, using -fprofile-instr-generate])
   PROFILE_COMPILER=clang
+  AC_MSG_RESULT([yes, using -fprofile-instr-generate])
 else
   if $enable_pgo = yes; then
     AC_MSG_ERROR(cannot use PGO with this compiler)
diff --git a/erts/emulator/Makefile.in b/erts/emulator/Makefile.in
index 2b203c9ee6..47d8ee8811 100644
--- a/erts/emulator/Makefile.in
+++ b/erts/emulator/Makefile.in
@@ -74,9 +74,8 @@ endif
 endif
 
 ifeq ($(PROFILE_COMPILER), gcc)
-PROFILE_CORRECTION=@PROFILE_CORRECTION@
 PROFILE_GENERATE=-fprofile-generate
-PROFILE_USE=-fprofile-use $(PROFILE_CORRECTION)
+PROFILE_USE=-fprofile-use -fprofile-correction
 PROFILE_USE_DEPS=$(OBJDIR)/%_pu.gcda
 endif
 ifeq ($(PROFILE_COMPILER), clang)
@@ -808,14 +807,7 @@ $(ERL_TOP)/lib/%.beam:
 
 INIT_OBJS = $(OBJDIR)/erl_main.o	$(PRELOAD_OBJ)
 
-# -fprofile-correction is needed in order to use PGO on erl_process
-# as multiple threads execute in that file.
-ifeq ($(PROFILE_CORRECTION),)
-PROFILE_OBJS = $(OBJDIR)/beam_emu.o
-RUN_OBJS = $(OBJDIR)/erl_process.o
-else
 PROFILE_OBJS = $(OBJDIR)/beam_emu.o	$(OBJDIR)/erl_process.o
-endif
 
 EMU_OBJS = \
 	$(OBJDIR)/beam_opcodes.o \
-- 
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