[RFA configure parts] aarch64: Make cc1 &co handle --with options

[Richard Sandiford <richard.sandiford@arm.com>]

On aarch64, --with-arch, --with-cpu and --with-tune only have an
effect on the driver, so “./xgcc -B./ -O3” can give significantly
different results from “./cc1 -O3”.  --with-arch did have a limited
effect on ./cc1 in previous releases, although it didn't work
entirely correctly.

Being of a lazy persuasion, I've got used to ./cc1 selecting SVE for
--with-arch=armv8.2-a+sve without having to supply an explicit -march,
so this patch makes ./cc1 emulate the relevant OPTION_DEFAULT_SPECS.
It relies on Wilco's earlier clean-ups.

The patch makes config.gcc define WITH_FOO_STRING macros for each
supported --with-foo option.  This could be done only in aarch64-
specific code, but I thought it could be useful on other targets
too (and can be safely ignored otherwise).  There didn't seem to
be any existing and potentially clashing uses of macros with this
style of name.

Tested on aarch64-linux-gnu & x86_64-linux-gnu.  OK for the configure
bits?

Richard


gcc/
	* config.gcc: Define WITH_FOO_STRING macros for each supported
	--with-foo option.
	* config/aarch64/aarch64.cc (aarch64_override_options): Emulate
	OPTION_DEFAULT_SPECS.
	* config/aarch64/aarch64.h (OPTION_DEFAULT_SPECS): Reference the above.
---
 gcc/config.gcc                | 14 ++++++++++++++
 gcc/config/aarch64/aarch64.cc |  8 ++++++++
 gcc/config/aarch64/aarch64.h  |  5 ++++-
 3 files changed, 26 insertions(+), 1 deletion(-)

diff --git a/gcc/config.gcc b/gcc/config.gcc
index cdbefb5b4f5..e039230431c 100644
--- a/gcc/config.gcc
+++ b/gcc/config.gcc
@@ -5865,6 +5865,20 @@ else
 	configure_default_options="{ ${t} }"
 fi
 
+for option in $supported_defaults
+do
+	lc_option=`echo $option | sed s/-/_/g`
+	uc_option=`echo $lc_option | tr a-z A-Z`
+	eval "val=\$with_$lc_option"
+	if test -n "$val"
+	then
+		val="\\\"$val\\\""
+	else
+		val=nullptr
+	fi
+	tm_defines="$tm_defines WITH_${uc_option}_STRING=$val"
+done
+
 if test "$target_cpu_default2" != ""
 then
 	if test "$target_cpu_default" != ""
diff --git a/gcc/config/aarch64/aarch64.cc b/gcc/config/aarch64/aarch64.cc
index d21e041eccb..0bc700b81ad 100644
--- a/gcc/config/aarch64/aarch64.cc
+++ b/gcc/config/aarch64/aarch64.cc
@@ -18109,6 +18109,14 @@ aarch64_override_options (void)
   if (aarch64_branch_protection_string)
     aarch64_validate_mbranch_protection (aarch64_branch_protection_string);
 
+  /* Emulate OPTION_DEFAULT_SPECS.  */
+  if (!aarch64_arch_string && !aarch64_cpu_string)
+    aarch64_arch_string = WITH_ARCH_STRING;
+  if (!aarch64_arch_string && !aarch64_cpu_string)
+    aarch64_cpu_string = WITH_CPU_STRING;
+  if (!aarch64_cpu_string && !aarch64_tune_string)
+    aarch64_tune_string = WITH_TUNE_STRING;
+
   /* -mcpu=CPU is shorthand for -march=ARCH_FOR_CPU, -mtune=CPU.
      If either of -march or -mtune is given, they override their
      respective component of -mcpu.  */
diff --git a/gcc/config/aarch64/aarch64.h b/gcc/config/aarch64/aarch64.h
index 80cfe4b7407..3122dbd7098 100644
--- a/gcc/config/aarch64/aarch64.h
+++ b/gcc/config/aarch64/aarch64.h
@@ -1267,7 +1267,10 @@ extern enum aarch64_code_model aarch64_cmodel;
 /* Support for configure-time --with-arch, --with-cpu and --with-tune.
    --with-arch and --with-cpu are ignored if either -mcpu or -march is used.
    --with-tune is ignored if either -mtune or -mcpu is used (but is not
-   affected by -march).  */
+   affected by -march).
+
+   There is corresponding code in aarch64_override_options that emulates
+   this behavior when cc1 &co are invoked directly.  */
 #define OPTION_DEFAULT_SPECS				\
   {"arch", "%{!march=*:%{!mcpu=*:-march=%(VALUE)}}" },	\
   {"cpu",  "%{!march=*:%{!mcpu=*:-mcpu=%(VALUE)}}" },   \
-- 
2.25.1