Hi,
While clarifying the documentation of the -mcpu, -march and -mtune
options for AArch64 and ARM I spotted that their behaviour is not
consistent.
This patch fixes that in the AArch64 port.
Now, -mcpu=$CPU is treated as a shorthand for -march=arch_of_$CPU and
-mtune=$CPU. -march and -mtune therefore override only their respective
components of -mcpu. If the architecture picked by -march does not match
that given by -mcpu, a warning is given.
Regression tested on aarch64-none-elf and checked manually to
ensure things are working as expected.
OK?
Thanks,
James
---
gcc/
2014-01-16 James Greenhalgh <james.greenha...@arm.com>
* common/config/aarch64/aarch64-common.c
(aarch64_handle_option): Don't handle any option order logic here.
* config/aarch64/aarch64.c (aarch64_parse_arch): Do not override
selected_cpu, warn on architecture version mismatch.
(aarch64_override_options): Fix parsing order for option strings.
diff --git a/gcc/common/config/aarch64/aarch64-common.c b/gcc/common/config/aarch64/aarch64-common.c
index 135a9bc..6107007 100644
--- a/gcc/common/config/aarch64/aarch64-common.c
+++ b/gcc/common/config/aarch64/aarch64-common.c
@@ -52,10 +52,10 @@ static const struct default_options aarch_option_optimization_table[] =
/* Implement TARGET_HANDLE_OPTION.
This function handles the target specific options for CPU/target selection.
- march wins over mcpu, so when march is defined, mcpu takes the same value,
- otherwise march remains undefined. mtune can be used with either march or
- mcpu. If march and mcpu are used together, the rightmost option wins.
- mtune can be used with either march or mcpu. */
+ -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. This logic is implemented
+ in config/aarch64/aarch64.c:aarch64_override_options. */
static bool
aarch64_handle_option (struct gcc_options *opts,
@@ -70,12 +70,10 @@ aarch64_handle_option (struct gcc_options *opts,
{
case OPT_march_:
opts->x_aarch64_arch_string = arg;
- opts->x_aarch64_cpu_string = arg;
return true;
case OPT_mcpu_:
opts->x_aarch64_cpu_string = arg;
- opts->x_aarch64_arch_string = NULL;
return true;
case OPT_mtune_:
diff --git a/gcc/config/aarch64/aarch64.c b/gcc/config/aarch64/aarch64.c
index 89f2b9b..59e9dd1 100644
--- a/gcc/config/aarch64/aarch64.c
+++ b/gcc/config/aarch64/aarch64.c
@@ -5099,7 +5099,9 @@ aarch64_parse_arch (void)
{
selected_arch = arch;
aarch64_isa_flags = selected_arch->flags;
- selected_cpu = &all_cores[selected_arch->core];
+
+ if (!selected_cpu)
+ selected_cpu = &all_cores[selected_arch->core];
if (ext != NULL)
{
@@ -5107,6 +5109,12 @@ aarch64_parse_arch (void)
aarch64_parse_extension (ext);
}
+ if (strcmp (selected_arch->arch, selected_cpu->arch))
+ {
+ warning (0, "switch -mcpu=%s conflicts with -march=%s switch",
+ selected_cpu->name, selected_arch->name);
+ }
+
return;
}
}
@@ -5195,20 +5203,21 @@ aarch64_parse_tune (void)
static void
aarch64_override_options (void)
{
- /* march wins over mcpu, so when march is defined, mcpu takes the same value,
- otherwise march remains undefined. mtune can be used with either march or
- mcpu. */
+ /* -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.
- if (aarch64_arch_string)
+ So, first parse AARCH64_CPU_STRING, then the others, be careful
+ with -march as, if -mcpu is not present on the command line, march
+ must set a sensible default CPU. */
+ if (aarch64_cpu_string)
{
- aarch64_parse_arch ();
- aarch64_cpu_string = NULL;
+ aarch64_parse_cpu ();
}
- if (aarch64_cpu_string)
+ if (aarch64_arch_string)
{
- aarch64_parse_cpu ();
- selected_arch = NULL;
+ aarch64_parse_arch ();
}
if (aarch64_tune_string)
