aarch64: Rewrite architecture strings for assembler

Add infrastructure to allow rewriting the architecture strings passed to
the assembler (either as -march options or .arch directives).  There was
already canonicalisation everywhere except for an -march driver option
passed directly to the compiler; this patch applies the same
canonicalisation there as well.

gcc/ChangeLog:

	* common/config/aarch64/aarch64-common.cc
	(aarch64_get_arch_string_for_assembler): New.
	(aarch64_rewrite_march): New.
	(aarch64_rewrite_selected_cpu): Call new function.
	* config/aarch64/aarch64-elf.h (ASM_SPEC): Remove identity mapping.
	* config/aarch64/aarch64-protos.h
	(aarch64_get_arch_string_for_assembler): New.
	* config/aarch64/aarch64.cc
	(aarch64_declare_function_name): Call new function.
	(aarch64_start_file): Ditto.
	* config/aarch64/aarch64.h
	(EXTRA_SPEC_FUNCTIONS): Use new macro name.
	(MCPU_TO_MARCH_SPEC): Rename to...
	(MARCH_REWRITE_SPEC): ...this, and extend the spec rule.
	(aarch64_rewrite_march): New declaration.
	(MCPU_TO_MARCH_SPEC_FUNCTIONS): Rename to...
	(AARCH64_BASE_SPEC_FUNCTIONS): ...this, and add new function.
	(ASM_CPU_SPEC): Use new macro name.

Author: andrewcarlotti

gcc/common/config/aarch64/aarch64-common.cc

@@ -690,6 +690,48 @@ aarch64_get_extension_string_for_isa_flags
   return outstr;
 }
 
+/* Generate an arch string to be passed to the assembler.  */
+
+std::string
+aarch64_get_arch_string_for_assembler (aarch64_arch arch,
+				       aarch64_feature_flags flags)
+{
+  const struct aarch64_arch_info *entry;
+  for (entry = all_architectures; entry->arch != aarch64_no_arch; entry++)
+    if (entry->arch == arch)
+	break;
+
+  std::string outstr = entry->name
+	+ aarch64_get_extension_string_for_isa_flags (flags, entry->flags);
+
+  return outstr;
+}
+
+/* Called by the driver to rewrite a name passed to the -march
+   argument in preparation to be passed to the assembler.  The
+   names passed from the commend line will be in ARGV, we want
+   to use the right-most argument, which should be in
+   ARGV[ARGC - 1].  ARGC should always be greater than 0.  */
+
+const char *
+aarch64_rewrite_march (int argc, const char **argv)
+{
+  gcc_assert (argc);
+  const char *name = argv[argc - 1];
+  aarch64_arch arch;
+  aarch64_feature_flags flags;
+
+  aarch64_validate_march (name, &arch, &flags);
+
+  std::string outstr = aarch64_get_arch_string_for_assembler (arch, flags);
+
+  /* We are going to memory leak here, nobody elsewhere
+     in the callchain is going to clean up after us.  The alternative is
+     to allocate a static buffer, and assert that it is big enough for our
+     modified string, which seems much worse!  */
+  return xstrdup (outstr.c_str ());
+}
+
 /* Attempt to rewrite NAME, which has been passed on the command line
    as a -mcpu option to an equivalent -march value.  If we can do so,
    return the new string, otherwise return an error.  */
@@ -733,7 +775,7 @@ aarch64_rewrite_selected_cpu (const char *name)
 	break;
     }
 
-  /* We couldn't find that proceesor name, or the processor name we
+  /* We couldn't find that processor name, or the processor name we
      found does not map to an architecture we understand.  */
   if (p_to_a->arch == aarch64_no_arch
       || a_to_an->arch == aarch64_no_arch)
@@ -742,9 +784,8 @@ aarch64_rewrite_selected_cpu (const char *name)
   aarch64_feature_flags extensions = p_to_a->flags;
   aarch64_parse_extension (extension_str.c_str (), &extensions, NULL);
 
-  std::string outstr = a_to_an->name
-	+ aarch64_get_extension_string_for_isa_flags (extensions,
-						      a_to_an->flags);
+  std::string outstr = aarch64_get_arch_string_for_assembler (a_to_an->arch,
+							      extensions);
 
   /* We are going to memory leak here, nobody elsewhere
      in the callchain is going to clean up after us.  The alternative is

gcc/config/aarch64/aarch64-elf.h

@@ -136,7 +136,6 @@
 #define ASM_SPEC "\
 %{mbig-endian:-EB} \
 %{mlittle-endian:-EL} \
-%{march=*:-march=%*} \
 %(asm_cpu_spec)" \
 ASM_MABI_SPEC
 #endif

gcc/config/aarch64/aarch64-protos.h

@@ -1213,6 +1213,8 @@ bool aarch64_validate_mtune (const char *, aarch64_cpu *);
 const char *aarch64_rewrite_selected_cpu (const char *name);
 std::string aarch64_get_extension_string_for_isa_flags (aarch64_feature_flags,
 							aarch64_feature_flags);
+std::string aarch64_get_arch_string_for_assembler (aarch64_arch,
+						   aarch64_feature_flags);
 
 rtl_opt_pass *make_pass_aarch64_early_ra (gcc::context *);
 rtl_opt_pass *make_pass_fma_steering (gcc::context *);

gcc/config/aarch64/aarch64.cc

@@ -24850,16 +24850,12 @@ aarch64_declare_function_name (FILE *stream, const char* name,
     targ_options = TREE_TARGET_OPTION (target_option_current_node);
   gcc_assert (targ_options);
 
-  const struct processor *this_arch
-    = aarch64_get_arch (targ_options->x_selected_arch);
-
   auto isa_flags = aarch64_get_asm_isa_flags (targ_options);
-  std::string extension
-    = aarch64_get_extension_string_for_isa_flags (isa_flags,
-						  this_arch->flags);
+  aarch64_arch arch = targ_options->x_selected_arch;
+  std::string to_print
+    = aarch64_get_arch_string_for_assembler (arch, isa_flags);
   /* Only update the assembler .arch string if it is distinct from the last
      such string we printed.  */
-  std::string to_print = this_arch->name + extension;
   if (to_print != aarch64_last_printed_arch_string)
     {
       asm_fprintf (asm_out_file, "\t.arch %s\n", to_print.c_str ());
@@ -24981,19 +24977,16 @@ aarch64_start_file (void)
   struct cl_target_option *default_options
     = TREE_TARGET_OPTION (target_option_default_node);
 
-  const struct processor *default_arch
-    = aarch64_get_arch (default_options->x_selected_arch);
+  aarch64_arch default_arch = default_options->x_selected_arch;
   auto default_isa_flags = aarch64_get_asm_isa_flags (default_options);
-  std::string extension
-    = aarch64_get_extension_string_for_isa_flags (default_isa_flags,
-						  default_arch->flags);
-
-   aarch64_last_printed_arch_string = default_arch->name + extension;
-   aarch64_last_printed_tune_string = "";
-   asm_fprintf (asm_out_file, "\t.arch %s\n",
-		aarch64_last_printed_arch_string.c_str ());
-
-   default_file_start ();
+  std::string arch_string
+    = aarch64_get_arch_string_for_assembler (default_arch, default_isa_flags);
+  aarch64_last_printed_arch_string = arch_string;
+  aarch64_last_printed_tune_string = "";
+  asm_fprintf (asm_out_file, "\t.arch %s\n",
+	       arch_string.c_str ());
+
+  default_file_start ();
 }
 
 /* Emit load exclusive.  */

gcc/config/aarch64/aarch64.h

@@ -1474,7 +1474,7 @@ extern const char *host_detect_local_cpu (int argc, const char **argv);
 #define HAVE_LOCAL_CPU_DETECT
 # define EXTRA_SPEC_FUNCTIONS                                           \
   { "local_cpu_detect", host_detect_local_cpu },                        \
-  MCPU_TO_MARCH_SPEC_FUNCTIONS
+  AARCH64_BASE_SPEC_FUNCTIONS
 
 /* Rewrite -m{arch,cpu,tune}=native based on the host system information.
    When rewriting -march=native convert it into an -mcpu option if no other
@@ -1491,7 +1491,7 @@ extern const char *host_detect_local_cpu (int argc, const char **argv);
  { "tune", "%{!mcpu=*:%{!mtune=*:%{!march=native:-mtune=%(VALUE)}}}" },
 #else
 # define MCPU_MTUNE_NATIVE_SPECS ""
-# define EXTRA_SPEC_FUNCTIONS MCPU_TO_MARCH_SPEC_FUNCTIONS
+# define EXTRA_SPEC_FUNCTIONS AARCH64_BASE_SPEC_FUNCTIONS
 # define CONFIG_TUNE_SPEC                                                \
   {"tune", "%{!mcpu=*:%{!mtune=*:-mtune=%(VALUE)}}"},
 #endif
@@ -1506,18 +1506,21 @@ extern const char *host_detect_local_cpu (int argc, const char **argv);
   {"cpu",  "%{!march=*:%{!mcpu=*:-mcpu=%(VALUE)}}" },   \
   CONFIG_TUNE_SPEC
 
-#define MCPU_TO_MARCH_SPEC \
-   "%{!march=*:%{mcpu=*:-march=%:rewrite_mcpu(%{mcpu=*:%*})}}"
+#define MARCH_REWRITE_SPEC \
+   "%{march=*:-march=%:rewrite_march(%{march=*:%*});" \
+     "mcpu=*:-march=%:rewrite_mcpu(%{mcpu=*:%*})}"
 
+extern const char *aarch64_rewrite_march (int argc, const char **argv);
 extern const char *aarch64_rewrite_mcpu (int argc, const char **argv);
 extern const char *is_host_cpu_not_armv8_base (int argc, const char **argv);
-#define MCPU_TO_MARCH_SPEC_FUNCTIONS		       \
+#define AARCH64_BASE_SPEC_FUNCTIONS		       \
+  { "rewrite_march", aarch64_rewrite_march },          \
   { "rewrite_mcpu",            aarch64_rewrite_mcpu }, \
   { "is_local_not_armv8_base", is_host_cpu_not_armv8_base },
 
 
 #define ASM_CPU_SPEC \
-   MCPU_TO_MARCH_SPEC
+   MARCH_REWRITE_SPEC
 
 #define EXTRA_SPECS						\
   { "asm_cpu_spec",		ASM_CPU_SPEC }