Split Makefile symbol CFLAGS_VECTOR into two symbols.

Replace CFLAGS_VECTOR with CFLAGS_UNROLL_LOOPS and CFLAGS_VECTORIZE,
allowing us to distinguish whether we want to apply -funroll-loops,
-ftree-vectorize, or both to a particular source file.  Up to now
the only consumer of the symbol has been checksum.c which wants
both, so that there was no need to distinguish; but that's about
to change.

Amit Khandekar, reviewed and edited a little by me

Discussion: https://postgr.es/m/CAJ3gD9evtA_vBo+WMYMyT-u=keHX7-r8p2w7OSRfXf42LTwCZQ@mail.gmail.com

configure

@@ -734,7 +734,8 @@ CPP
 CFLAGS_SL
 BITCODE_CXXFLAGS
 BITCODE_CFLAGS
-CFLAGS_VECTOR
+CFLAGS_VECTORIZE
+CFLAGS_UNROLL_LOOPS
 PERMIT_DECLARATION_AFTER_STATEMENT
 LLVM_BINPATH
 LLVM_CXXFLAGS
@@ -5266,9 +5267,12 @@ BITCODE_CFLAGS=""
 user_BITCODE_CXXFLAGS=$BITCODE_CXXFLAGS
 BITCODE_CXXFLAGS=""
 
-# set CFLAGS_VECTOR from the environment, if available
-if test "$ac_env_CFLAGS_VECTOR_set" = set; then
-  CFLAGS_VECTOR=$ac_env_CFLAGS_VECTOR_value
+# set CFLAGS_UNROLL_LOOPS and CFLAGS_VECTORIZE from the environment, if present
+if test "$ac_env_CFLAGS_UNROLL_LOOPS_set" = set; then
+  CFLAGS_UNROLL_LOOPS=$ac_env_CFLAGS_UNROLL_LOOPS_value
+fi
+if test "$ac_env_CFLAGS_VECTORIZE_set" = set; then
+  CFLAGS_VECTORIZE=$ac_env_CFLAGS_VECTORIZE_value
 fi
 
 # Some versions of GCC support some additional useful warning flags.
@@ -6102,16 +6106,16 @@ if test x"$pgac_cv_prog_CXX_cxxflags__fexcess_precision_standard" = x"yes"; then
 fi
 
 
-  # Optimization flags for specific files that benefit from vectorization
-  { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether ${CC} supports -funroll-loops, for CFLAGS_VECTOR" >&5
-$as_echo_n "checking whether ${CC} supports -funroll-loops, for CFLAGS_VECTOR... " >&6; }
+  # Optimization flags for specific files that benefit from loop unrolling
+  { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether ${CC} supports -funroll-loops, for CFLAGS_UNROLL_LOOPS" >&5
+$as_echo_n "checking whether ${CC} supports -funroll-loops, for CFLAGS_UNROLL_LOOPS... " >&6; }
 if ${pgac_cv_prog_CC_cflags__funroll_loops+:} false; then :
   $as_echo_n "(cached) " >&6
 else
   pgac_save_CFLAGS=$CFLAGS
 pgac_save_CC=$CC
 CC=${CC}
-CFLAGS="${CFLAGS_VECTOR} -funroll-loops"
+CFLAGS="${CFLAGS_UNROLL_LOOPS} -funroll-loops"
 ac_save_c_werror_flag=$ac_c_werror_flag
 ac_c_werror_flag=yes
 cat confdefs.h - <<_ACEOF >conftest.$ac_ext
@@ -6138,19 +6142,20 @@ fi
 { $as_echo "$as_me:${as_lineno-$LINENO}: result: $pgac_cv_prog_CC_cflags__funroll_loops" >&5
 $as_echo "$pgac_cv_prog_CC_cflags__funroll_loops" >&6; }
 if test x"$pgac_cv_prog_CC_cflags__funroll_loops" = x"yes"; then
-  CFLAGS_VECTOR="${CFLAGS_VECTOR} -funroll-loops"
+  CFLAGS_UNROLL_LOOPS="${CFLAGS_UNROLL_LOOPS} -funroll-loops"
 fi
 
 
-  { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether ${CC} supports -ftree-vectorize, for CFLAGS_VECTOR" >&5
-$as_echo_n "checking whether ${CC} supports -ftree-vectorize, for CFLAGS_VECTOR... " >&6; }
+  # Optimization flags for specific files that benefit from vectorization
+  { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether ${CC} supports -ftree-vectorize, for CFLAGS_VECTORIZE" >&5
+$as_echo_n "checking whether ${CC} supports -ftree-vectorize, for CFLAGS_VECTORIZE... " >&6; }
 if ${pgac_cv_prog_CC_cflags__ftree_vectorize+:} false; then :
   $as_echo_n "(cached) " >&6
 else
   pgac_save_CFLAGS=$CFLAGS
 pgac_save_CC=$CC
 CC=${CC}
-CFLAGS="${CFLAGS_VECTOR} -ftree-vectorize"
+CFLAGS="${CFLAGS_VECTORIZE} -ftree-vectorize"
 ac_save_c_werror_flag=$ac_c_werror_flag
 ac_c_werror_flag=yes
 cat confdefs.h - <<_ACEOF >conftest.$ac_ext
@@ -6177,7 +6182,7 @@ fi
 { $as_echo "$as_me:${as_lineno-$LINENO}: result: $pgac_cv_prog_CC_cflags__ftree_vectorize" >&5
 $as_echo "$pgac_cv_prog_CC_cflags__ftree_vectorize" >&6; }
 if test x"$pgac_cv_prog_CC_cflags__ftree_vectorize" = x"yes"; then
-  CFLAGS_VECTOR="${CFLAGS_VECTOR} -ftree-vectorize"
+  CFLAGS_VECTORIZE="${CFLAGS_VECTORIZE} -ftree-vectorize"
 fi
 
 
@@ -6782,6 +6787,7 @@ fi
 
 
 
+
 # Determine flags used to emit bitcode for JIT inlining. Need to test
 # for behaviour changing compiler flags, to keep compatibility with
 # compiler used for normal postgres code.

configure.ac

@@ -466,9 +466,12 @@ BITCODE_CFLAGS=""
 user_BITCODE_CXXFLAGS=$BITCODE_CXXFLAGS
 BITCODE_CXXFLAGS=""
 
-# set CFLAGS_VECTOR from the environment, if available
-if test "$ac_env_CFLAGS_VECTOR_set" = set; then
-  CFLAGS_VECTOR=$ac_env_CFLAGS_VECTOR_value
+# set CFLAGS_UNROLL_LOOPS and CFLAGS_VECTORIZE from the environment, if present
+if test "$ac_env_CFLAGS_UNROLL_LOOPS_set" = set; then
+  CFLAGS_UNROLL_LOOPS=$ac_env_CFLAGS_UNROLL_LOOPS_value
+fi
+if test "$ac_env_CFLAGS_VECTORIZE_set" = set; then
+  CFLAGS_VECTORIZE=$ac_env_CFLAGS_VECTORIZE_value
 fi
 
 # Some versions of GCC support some additional useful warning flags.
@@ -512,9 +515,10 @@ if test "$GCC" = yes -a "$ICC" = no; then
   # Disable FP optimizations that cause various errors on gcc 4.5+ or maybe 4.6+
   PGAC_PROG_CC_CFLAGS_OPT([-fexcess-precision=standard])
   PGAC_PROG_CXX_CFLAGS_OPT([-fexcess-precision=standard])
+  # Optimization flags for specific files that benefit from loop unrolling
+  PGAC_PROG_CC_VAR_OPT(CFLAGS_UNROLL_LOOPS, [-funroll-loops])
   # Optimization flags for specific files that benefit from vectorization
-  PGAC_PROG_CC_VAR_OPT(CFLAGS_VECTOR, [-funroll-loops])
-  PGAC_PROG_CC_VAR_OPT(CFLAGS_VECTOR, [-ftree-vectorize])
+  PGAC_PROG_CC_VAR_OPT(CFLAGS_VECTORIZE, [-ftree-vectorize])
   # We want to suppress clang's unhelpful unused-command-line-argument warnings
   # but gcc won't complain about unrecognized -Wno-foo switches, so we have to
   # test for the positive form and if that works, add the negative form
@@ -555,7 +559,8 @@ elif test "$PORTNAME" = "hpux"; then
   PGAC_PROG_CXX_CFLAGS_OPT([+Olibmerrno])
 fi
 
-AC_SUBST(CFLAGS_VECTOR)
+AC_SUBST(CFLAGS_UNROLL_LOOPS)
+AC_SUBST(CFLAGS_VECTORIZE)
 
 # Determine flags used to emit bitcode for JIT inlining. Need to test
 # for behaviour changing compiler flags, to keep compatibility with

src/Makefile.global.in

@@ -259,7 +259,8 @@ SUN_STUDIO_CC = @SUN_STUDIO_CC@
 CXX = @CXX@
 CFLAGS = @CFLAGS@
 CFLAGS_SL = @CFLAGS_SL@
-CFLAGS_VECTOR = @CFLAGS_VECTOR@
+CFLAGS_UNROLL_LOOPS = @CFLAGS_UNROLL_LOOPS@
+CFLAGS_VECTORIZE = @CFLAGS_VECTORIZE@
 CFLAGS_SSE42 = @CFLAGS_SSE42@
 CFLAGS_ARMV8_CRC32C = @CFLAGS_ARMV8_CRC32C@
 PERMIT_DECLARATION_AFTER_STATEMENT = @PERMIT_DECLARATION_AFTER_STATEMENT@

src/backend/storage/page/Makefile

@@ -19,5 +19,5 @@ OBJS =  \
 
 include $(top_srcdir)/src/backend/common.mk
 
-# important optimizations flags for checksum.c
-checksum.o: CFLAGS += ${CFLAGS_VECTOR}
+# Provide special optimization flags for checksum.c
+checksum.o: CFLAGS += ${CFLAGS_UNROLL_LOOPS} ${CFLAGS_VECTORIZE}