BUILD: makefile: get rid of the CPU variable

The CPU variable, when used, is almost always exclusively used with
"generic" to disable any CPU-specific optimizations, or "native" to
enable "-march=native". Other options are not used and are just making
CPU_CFLAGS more confusing.

This commit just drops all pre-configured variants and replaces them
with documentation about examples of supported options. CPU_CFLAGS is
preserved as it appears that it's mostly used as a proxy to inject the
distro's CFLAGS, and it's just empty by default.

The CPU variable is checked, and if set to anything but "generic", it
emits a warning about its deprecation and invites the user to read
INSTALL.

Users who would just set CPU_CFLAGS will be able to continue to do so,
those who were using CPU=native will have to pass CPU_CFLAGS=-march=native
and those who were passing one of the other options will find it in the
doc as well.

Note that this also removes the "CPU=" line from haproxy -vv, that most
users got used to seeing set to "generic" or occasionally "native"
anyway, thus that didn't provide any useful information.

diff --git a/INSTALL b/INSTALL
index a2b96e105e8873ceb7e0bca24ed6b0b76c758253..c13bd81869b54df4d60ebe728730f865310487be 100644 (file)
--- a/INSTALL
+++ b/INSTALL
@@ -45,7 +45,7 @@ are a few build examples :
                 CC=/opt/cross/gcc730-arm/bin/gcc ADDLIB=-latomic
 
   - Build with static PCRE on Solaris / UltraSPARC :
-    $ make TARGET=solaris CPU=ultrasparc USE_STATIC_PCRE2=1
+    $ make TARGET=solaris CPU_CFLAGS="-mcpu=v9" USE_STATIC_PCRE2=1
 
 For more advanced build options or if a command above reports an error, please
 read the following sections.
@@ -558,27 +558,6 @@ and assign it to the TARGET variable :
   - generic             for any other OS or version.
   - custom              to manually adjust every setting
 
-You may also choose your CPU to benefit from some optimizations. This is
-particularly important on UltraSparc machines. For this, you can assign
-one of the following choices to the CPU variable :
-
-  - i686 for intel PentiumPro, Pentium 2 and above, AMD Athlon (32 bits)
-  - i586 for intel Pentium, AMD K6, VIA C3.
-  - ultrasparc : Sun UltraSparc I/II/III/IV processor
-  - power8 : IBM POWER8 processor
-  - power9 : IBM POWER9 processor
-  - armv81 : modern ARM cores (Cortex A55/A75/A76/A78/X1, Neoverse, Graviton2)
-  - a72    : ARM Cortex-A72 or A73 (e.g. RPi4, Odroid N2, AWS Graviton)
-  - a53    : ARM Cortex-A53 or any of its successors in 64-bit mode (e.g. RPi3)
-  - armv8-auto : support both older and newer armv8 cores with a minor penalty,
-                 thanks to gcc 10's outline atomics (default with gcc 10.2).
-  - native : use the build machine's specific processor optimizations. Use with
-    extreme care, and never in virtualized environments (known to break).
-  - generic : any other processor or no CPU-specific optimization. (default)
-
-Alternatively, you may just set the CPU_CFLAGS value to the optimal GCC options
-for your platform.
-
 A generic CFLAGS variable may be set to append any option to pass to the C
 compiler. These flags are passed last so the variable may be used to override
 other options such as warnings, optimization levels, include paths etc.
@@ -587,6 +566,29 @@ A default optimization level of -O2 is set by variable OPT_CFLAGS which may be
 overridden if desired. It's used early in the list of CFLAGS so that any other
 set of CFLAGS providing a different value may easily override it.
 
+Some platforms may benefit from some CPU-specific options that will enable
+certain instruction sets, word size or endianness for example. One of them is
+the common "-march=native" that indicates to modern compilers that they need to
+optimize for the machine the compiler is running on. Such options may be either
+passed in the CPU_CFLAGS or in the CFLAGS variable, either will work though
+one may be more convenient for certain methods of packaging and the other one
+for other methods. Among the many possible options, the following ones are
+known for having successfully been used:
+
+  - "-march=native" for a native build
+  - "-march=armv8-a+crc" for older ARM Cortex A53/A72/A73 (such as RPi 3B/4B)
+  - "-march=armv8.1-a" for modern ARM Cortex A55/A76, Graviton2+, RPi 5
+  - "-march=armv8-a+crc -moutline-atomics" to support older ARM with better
+      support of modern cores with gcc-10+
+  - "-mavx", "-mavx2", "-mavx512", to enable certain x86 SIMD instruction sets
+  - "-march=i586" to support almost all 32-bit x86 systems
+  - "-march=i686" to support only the latest 32-bit x86 systems
+  - "-march=i386" to support even the oldest 32-bit x86 systems
+  - "-mlittle-endian -march=armv5te" for some little-endian ARMv5 systems
+  - "-mcpu=v9 -mtune=ultrasparc -m64" for a 64-bit Solaris SPARC build
+  - "-march=1004kc -mtune=1004kc" for some multi-core 32-bit MIPS 1004Kc
+  - "-march=24kc -mtune=24kc" for some single-core 32-bit MIPS 24Kc
+
 If you are building for a different system than the one you're building on,
 this is called "cross-compiling". HAProxy supports cross-compilation pretty
 well and tries to ease it by letting you adjust paths to all libraries (please

diff --git a/Makefile b/Makefile
index 836b9770801c0529a511ac333a6bf7675a417352..cd5538f16c7f63a41a4ecbf30cee01ad51de3dd6 100644 (file)
--- a/Makefile
+++ b/Makefile
@@ -1,7 +1,7 @@
 # This GNU Makefile supports different OS and CPU combinations.
 #
 # You should use it this way :
-#   [g]make TARGET=os [ARCH=arch] [CPU=cpu] USE_xxx=1 ...
+#   [g]make TARGET=os [ARCH=arch] [CFLAGS=...] USE_xxx=1 ...
 #
 # When in doubt, invoke help, possibly with a known target :
 #   [g]make help
@@ -152,12 +152,16 @@ DOCDIR = $(PREFIX)/doc/haproxy
 #    custom
 TARGET =
 
-#### TARGET CPU
-# Use CPU=<cpu_name> to optimize for a particular CPU, among the following
-# list :
-#    generic, native, i586, i686, ultrasparc, power8, power9, custom,
-#    a53, a72, armv81, armv8-auto
-CPU = generic
+#### No longer used
+CPU =
+ifneq ($(CPU),)
+ifneq ($(CPU),generic)
+$(warning Warning: the "CPU" variable was forced to "$(CPU)" but is no longer \
+  used and will be ignored. For native builds, modern compilers generally     \
+  prefer that the string "-march=native" is passed in CPU_CFLAGS or CFLAGS.   \
+  For other CPU-specific options, please read suggestions in the INSTALL file.)
+endif
+endif
 
 #### Architecture, used when not building for native architecture
 # Use ARCH=<arch_name> to force build for a specific architecture. Known
@@ -260,22 +264,12 @@ SILENT_DEFINE =
 EXTRA =
 
 #### CPU dependent optimizations
-# Some CFLAGS are set by default depending on the target CPU. Those flags only
-# feed CPU_CFLAGS, which in turn feed CFLAGS, so it is not mandatory to use
-# them. You should not have to change these options. Better use CPU_CFLAGS or
-# even CFLAGS instead.
-CPU_CFLAGS.generic    =
-CPU_CFLAGS.native     = -march=native
-CPU_CFLAGS.i586       = -march=i586
-CPU_CFLAGS.i686       = -march=i686
-CPU_CFLAGS.ultrasparc = -mcpu=v9 -mtune=ultrasparc
-CPU_CFLAGS.power8     = -mcpu=power8 -mtune=power8
-CPU_CFLAGS.power9     = -mcpu=power9 -mtune=power9
-CPU_CFLAGS.a53        = -mcpu=cortex-a53
-CPU_CFLAGS.a72        = -mcpu=cortex-a72
-CPU_CFLAGS.armv81     = -march=armv8.1-a
-CPU_CFLAGS.armv8-auto = -march=armv8-a+crc -moutline-atomics
-CPU_CFLAGS            = $(CPU_CFLAGS.$(CPU))
+# This may optionally be used to pass CPU-specific optimizations such as
+# -march=native, -mcpu=something, -m64 etc independently of CFLAGS if it is
+# considered more convenient. Historically, the optimization level was also
+# passed there. This is still supported but not recommended though; OPT_CFLAGS
+# is better suited. The default is empty.
+CPU_CFLAGS        =
 
 #### ARCH dependent flags, may be overridden by CPU flags
 ARCH_FLAGS.32     = -m32
@@ -1049,7 +1043,6 @@ src/haproxy.o:    src/haproxy.c $(DEP)
        $(cmd_CC) $(COPTS) \
              -DBUILD_TARGET='"$(strip $(TARGET))"' \
              -DBUILD_ARCH='"$(strip $(ARCH))"' \
-             -DBUILD_CPU='"$(strip $(CPU))"' \
              -DBUILD_CC='"$(strip $(CC))"' \
              -DBUILD_CFLAGS='"$(strip $(VERBOSE_CFLAGS))"' \
              -DBUILD_OPTIONS='"$(strip $(BUILD_OPTIONS))"' \
@@ -1152,7 +1145,6 @@ opts:
        @echo -n 'Using: '
        @echo -n 'TARGET="$(strip $(TARGET))" '
        @echo -n 'ARCH="$(strip $(ARCH))" '
-       @echo -n 'CPU="$(strip $(CPU))" '
        @echo -n 'CC="$(strip $(CC))" '
        @echo -n 'OPT_CFLAGS="$(strip $(OPT_CFLAGS))" '
        @echo -n 'ARCH_FLAGS="$(strip $(ARCH_FLAGS))" '

diff --git a/src/haproxy.c b/src/haproxy.c
index 587295734ca6bbfcde3599ada3fb96e6f6ff9e30..208c9bccb527af0475b0e4f21ea61ae227847d28 100644 (file)
--- a/src/haproxy.c
+++ b/src/haproxy.c
@@ -565,9 +565,6 @@ static void display_build_opts()
 #ifdef BUILD_TARGET
               "\n  TARGET  = " BUILD_TARGET
 #endif
-#ifdef BUILD_CPU
-              "\n  CPU     = " BUILD_CPU
-#endif
 #ifdef BUILD_CC
               "\n  CC      = " BUILD_CC
 #endif
@@ -2808,9 +2805,6 @@ static void init(int argc, char **argv)
 #ifdef BUILD_TARGET
        chunk_appendf(&trash, "TARGET='%s'", BUILD_TARGET);
 #endif
-#ifdef BUILD_CPU
-       chunk_appendf(&trash, " CPU='%s'", BUILD_CPU);
-#endif
 #ifdef BUILD_OPTIONS
        chunk_appendf(&trash, " %s", BUILD_OPTIONS);
 #endif
@@ -3367,9 +3361,6 @@ int main(int argc, char **argv)
 #ifdef BUILD_TARGET
                        "\n  TARGET  = " BUILD_TARGET
 #endif
-#ifdef BUILD_CPU
-                       "\n  CPU     = " BUILD_CPU
-#endif
 #ifdef BUILD_CC
                        "\n  CC      = " BUILD_CC
 #endif