Re: [PATCH, gas/ARM] Clean up selection of feature bits

[Thomas Preudhomme <thomas dot preudhomme at foss dot arm dot com>]

Hi Nick,

Thank you for the approval and the quick review. I've noticed one more issue in 
mark_feature_used which was referring to selected architecture but testing 
cpu_variant (which only represents what is allowed). I've considered this to be 
an obvious fix so have committed the patch with that comment fix.

You'll find attached the patch I've committed. As I said, the only difference is 
in mark_feature_used so just search for that function if you want to double check.

Updated ChangeLog entry is as follows:

*** gas/ChangeLog ***

2018-03-01  Thomas Preud'homme  <thomas.preudhomme@arm.com>

	* config/tc-arm.c (cpu_variant, arm_arch_used, thumb_arch_used,
	legacy_cpu, legacy_fpu, mcpu_cpu_opt, dyn_mcpu_ext_opt,
	mcpu_fpu_opt, march_cpu_opt, dyn_march_ext_opt, march_fpu_opt,
	mfpu_opt, object_arch, selected_cpu): Comment meaning of variables.
	(dyn_mcpu_ext_opt): Also rename into ...
	(mcpu_ext_opt): This.
	(dyn_march_ext_opt): Also rename into ...
	(march_ext_opt): This.
	(object_arch): Also rename into ...
	(selected_object_arch): This and make it a plain arm_feature_set
	structure.
	(selected_arch, selected_ext, selected_fpu): New static variables.
	(mark_feature_used): Fix comments, feature is marked as used iff
	it is currently allowed.
	(do_bx): Adapt to change in name and type of object_arch.
	(md_begin): Set selected_arch rather than mcpu_cpu_opt, selected_ext
	rather than dyn_mcpu_ext_opt and selected_fpu rather than mfpu_opt.
	Remove dead code to set default FPU if architecture version is greater
	than 5.  Set all CPU bits of cpu_variant directly in autodection
	leaving mcpu_cpu_opt, selected_arch and selected_cpu unset.
	(arm_parse_extension): Take extension feature set pointer
	parameter by value rather than by pointer.  Remove allocation
	code.  Adapt code accordingly.
	(arm_parse_cpu): Adapt to variable renaming and changes in
	arm_parse_extension () signature.
	(arm_parse_arch): Likewise.
	(aeabi_set_public_attributes): Also set selected_arch and selected_ext
	in addition to selected_cpu.  Set flags_arch and flags_ext from them
	instead of selected_cpu.  Adapt to variables renaming and type change.
	(arm_md_post_relax): Adapt to variable renaming.
	(s_arm_cpu): Set selcted_cpu_cpu and selected_ext instead of
	mcpu_cpu_opt and dyn_mcpu_ext_opt.  Set selected_cpu from them
	and cpu_variant from selected_cpu and selected_fpu.
	(s_arm_arch): Likewise.
	(s_arm_object_arch): Adapt to variable renaming.
	(s_arm_arch_extension): Use ARM_CPU_IS_ANY instead of checking
	feature set against arm_any.  Check selected_arch rather than
	*mcpu_cpu_opt.  Set selected_ext rather than *dyn_mcpu_ext_opt and
	remove allocation code.
	(s_arm_fpu): Set selected_fpu instead of mfpu_opt.  Set all CPU
	feature bits if in autodetection mode.

Best regards,

Thomas

On 01/03/18 10:58, Nick Clifton wrote:
> Hi Thomas,
>
> > I've always found the code in ARM backend of gas to control what
> > CPU/architecture and FPU are selected by the user and to support
> > autodetection of features complex and confusing. Chief among the
> > issues I have with that code is the lack of comments to explain
> > the meaning of the various variables. This patch addresses that
> > and much more:
>
> Wow - thank you for doing this.
>
> My first thought actually was whether this improvement ought to be generalized
> and used for other targets, and not just ARM.  I think however that there is
> probably too much target specific knowledge to be handled, but it might be worth
> thinking about for the future.
>
> > *** gas/ChangeLog ***
> > 2018-02-21  Thomas Preud'homme  <thomas.preudhomme@arm.com>
> >
> >      * config/tc-arm.c (cpu_variant, arm_arch_used, thumb_arch_used,
> >      legacy_cpu, legacy_fpu, mcpu_cpu_opt, dyn_mcpu_ext_opt,
> >      mcpu_fpu_opt, march_cpu_opt, dyn_march_ext_opt, march_fpu_opt,
> >      mfpu_opt, object_arch, selected_cpu): Comment meaning of variables.
> >      (dyn_mcpu_ext_opt): Also rename into ...
> >      (mcpu_ext_opt): This.
> >      (dyn_march_ext_opt): Also rename into ...
> >      (march_ext_opt): This.
> >      (object_arch): Also rename into ...
> >      (selected_object_arch): This and make it a plain arm_feature_set
> >      structure.
> >      (selected_arch, selected_ext, selected_fpu): New static variables.
> >      (do_bx): Adapt to change in name and type of object_arch.
> >      (md_begin): Set selected_arch rather than mcpu_cpu_opt, selected_ext
> >      rather than dyn_mcpu_ext_opt and selected_fpu rather than mfpu_opt.
> >      Remove dead code to set default FPU if architecture version is greater
> >      than 5.  Set all CPU bits of cpu_variant directly in autodection
> >      leaving mcpu_cpu_opt, selected_arch and selected_cpu unset.
> >      (arm_parse_extension): Take extension feature set pointer
> >      parameter by value rather than by pointer.  Remove allocation
> >      code.  Adapt code accordingly.
> >      (arm_parse_cpu): Adapt to variable renaming and changes in
> >      arm_parse_extension () signature.
> >      (arm_parse_arch): Likewise.
> >      (aeabi_set_public_attributes): Also set selected_arch and selected_ext
> >      in addition to selected_cpu.  Set flags_arch and flags_ext from them
> >      instead of selected_cpu.  Adapt to variables renaming and type change.
> >      (arm_md_post_relax): Adapt to variable renaming.
> >      (s_arm_cpu): Set selcted_cpu_cpu and selected_ext instead of
> >      mcpu_cpu_opt and dyn_mcpu_ext_opt.  Set selected_cpu from them
> >      and cpu_variant from selected_cpu and selected_fpu.
> >      (s_arm_arch): Likewise.
> >      (s_arm_object_arch): Adapt to variable renaming.
> >      (s_arm_arch_extension): Use ARM_CPU_IS_ANY instead of checking
> >      feature set against arm_any.  Check selected_arch rather than
> >      *mcpu_cpu_opt.  Set selected_ext rather than *dyn_mcpu_ext_opt and
> >      remove allocation code.
> >      (s_arm_fpu): Set selected_fpu instead of mfpu_opt.  Set all CPU
> >      feature bits if in autodetection mode.
>
> Approved - please apply.
>
> Cheers
>    Nick
diff --git a/gas/config/tc-arm.c b/gas/config/tc-arm.c
index d6a923d9b9853f30b47dd8ac7817b1e4d1cfdbd2..ac403cc74e9871721f1b522239997241eddefb4f 100644
--- a/gas/config/tc-arm.c
+++ b/gas/config/tc-arm.c
@@ -123,7 +123,12 @@ enum arm_float_abi
 
 #define streq(a, b)	      (strcmp (a, b) == 0)
 
+/* Current set of feature bits available (CPU+FPU).  Different from
+   selected_cpu + selected_fpu in case of autodetection since the CPU
+   feature bits are then all set.  */
 static arm_feature_set cpu_variant;
+/* Feature bits used in each execution state.  Used to set build attribute
+   (in particular Tag_*_ISA_use) in CPU autodetection mode.  */
 static arm_feature_set arm_arch_used;
 static arm_feature_set thumb_arch_used;
 
@@ -143,17 +148,24 @@ bfd_boolean codecomposer_syntax = FALSE;
 /* Variables that we set while parsing command-line options.  Once all
    options have been read we re-process these values to set the real
    assembly flags.  */
-static const arm_feature_set *  legacy_cpu = NULL;
-static const arm_feature_set *  legacy_fpu = NULL;
-
-static const arm_feature_set *  mcpu_cpu_opt = NULL;
-static arm_feature_set *        dyn_mcpu_ext_opt = NULL;
-static const arm_feature_set *  mcpu_fpu_opt = NULL;
-static const arm_feature_set *  march_cpu_opt = NULL;
-static arm_feature_set *        dyn_march_ext_opt = NULL;
-static const arm_feature_set *  march_fpu_opt = NULL;
-static const arm_feature_set *  mfpu_opt = NULL;
-static const arm_feature_set *  object_arch = NULL;
+
+/* CPU and FPU feature bits set for legacy CPU and FPU options (eg. -marm1
+   instead of -mcpu=arm1).  */
+static const arm_feature_set *legacy_cpu = NULL;
+static const arm_feature_set *legacy_fpu = NULL;
+
+/* CPU, extension and FPU feature bits selected by -mcpu.  */
+static const arm_feature_set *mcpu_cpu_opt = NULL;
+static arm_feature_set *mcpu_ext_opt = NULL;
+static const arm_feature_set *mcpu_fpu_opt = NULL;
+
+/* CPU, extension and FPU feature bits selected by -march.  */
+static const arm_feature_set *march_cpu_opt = NULL;
+static arm_feature_set *march_ext_opt = NULL;
+static const arm_feature_set *march_fpu_opt = NULL;
+
+/* Feature bits selected by -mfpu.  */
+static const arm_feature_set *mfpu_opt = NULL;
 
 /* Constants for known architecture features.  */
 static const arm_feature_set fpu_default = FPU_DEFAULT;
@@ -302,8 +314,20 @@ static const arm_feature_set fpu_neon_ext_dotprod =
   ARM_FEATURE_COPROC (FPU_NEON_EXT_DOTPROD);
 
 static int mfloat_abi_opt = -1;
-/* Record user cpu selection for object attributes.  */
+/* Architecture feature bits selected by the last -mcpu/-march or .cpu/.arch
+   directive.  */
+static arm_feature_set selected_arch = ARM_ARCH_NONE;
+/* Extension feature bits selected by the last -mcpu/-march or .arch_extension
+   directive.  */
+static arm_feature_set selected_ext = ARM_ARCH_NONE;
+/* Feature bits selected by the last -mcpu/-march or by the combination of the
+   last .cpu/.arch directive .arch_extension directives since that
+   directive.  */
 static arm_feature_set selected_cpu = ARM_ARCH_NONE;
+/* FPU feature bits selected by the last -mfpu or .fpu directive.  */
+static arm_feature_set selected_fpu = FPU_NONE;
+/* Feature bits selected by the last .object_arch directive.  */
+static arm_feature_set selected_object_arch = ARM_ARCH_NONE;
 /* Must be long enough to hold any of the names in arm_cpus.  */
 static char selected_cpu_name[20];
 
@@ -6160,17 +6184,16 @@ record_feature_use (const arm_feature_set *feature)
     ARM_MERGE_FEATURE_SETS (arm_arch_used, arm_arch_used, *feature);
 }
 
-/* If the given feature available in the selected CPU, mark it as used.
-   Returns TRUE iff feature is available.  */
+/* If the given feature is currently allowed, mark it as used and return TRUE.
+   Return FALSE otherwise.  */
 static bfd_boolean
 mark_feature_used (const arm_feature_set *feature)
 {
-  /* Ensure the option is valid on the current architecture.  */
+  /* Ensure the option is currently allowed.  */
   if (!ARM_CPU_HAS_FEATURE (cpu_variant, *feature))
     return FALSE;
 
-  /* Add the appropriate architecture feature for the barrier option used.
-     */
+  /* Add the appropriate architecture feature for the barrier option used.  */
   record_feature_use (feature);
 
   return TRUE;
@@ -8610,7 +8633,8 @@ do_bx (void)
   /* Output R_ARM_V4BX relocations if is an EABI object that looks like
      it is for ARMv4t or earlier.  */
   want_reloc = !ARM_CPU_HAS_FEATURE (selected_cpu, arm_ext_v5);
-  if (object_arch && !ARM_CPU_HAS_FEATURE (*object_arch, arm_ext_v5))
+  if (!ARM_FEATURE_ZERO (selected_object_arch)
+      && !ARM_CPU_HAS_FEATURE (selected_object_arch, arm_ext_v5))
       want_reloc = TRUE;
 
 #ifdef OBJ_ELF
@@ -25352,71 +25376,70 @@ md_begin (void)
       if (mcpu_cpu_opt || march_cpu_opt)
 	as_bad (_("use of old and new-style options to set CPU type"));
 
-      mcpu_cpu_opt = legacy_cpu;
+      selected_arch = *legacy_cpu;
     }
-  else if (!mcpu_cpu_opt)
+  else if (mcpu_cpu_opt)
+    {
+      selected_arch = *mcpu_cpu_opt;
+      selected_ext = *mcpu_ext_opt;
+    }
+  else if (march_cpu_opt)
     {
-      mcpu_cpu_opt = march_cpu_opt;
-      dyn_mcpu_ext_opt = dyn_march_ext_opt;
-      /* Avoid double free in arm_md_end.  */
-      dyn_march_ext_opt = NULL;
+      selected_arch = *march_cpu_opt;
+      selected_ext = *march_ext_opt;
     }
+  ARM_MERGE_FEATURE_SETS (selected_cpu, selected_arch, selected_ext);
 
   if (legacy_fpu)
     {
       if (mfpu_opt)
 	as_bad (_("use of old and new-style options to set FPU type"));
 
-      mfpu_opt = legacy_fpu;
+      selected_fpu = *legacy_fpu;
     }
-  else if (!mfpu_opt)
+  else if (mfpu_opt)
+    selected_fpu = *mfpu_opt;
+  else
     {
 #if !(defined (EABI_DEFAULT) || defined (TE_LINUX) \
 	|| defined (TE_NetBSD) || defined (TE_VXWORKS))
       /* Some environments specify a default FPU.  If they don't, infer it
 	 from the processor.  */
       if (mcpu_fpu_opt)
-	mfpu_opt = mcpu_fpu_opt;
+	selected_fpu = *mcpu_fpu_opt;
       else
-	mfpu_opt = march_fpu_opt;
+	selected_fpu = *march_fpu_opt;
 #else
-      mfpu_opt = &fpu_default;
+      selected_fpu = fpu_default;
 #endif
     }
 
-  if (!mfpu_opt)
+  if (ARM_FEATURE_ZERO (selected_fpu))
     {
-      if (mcpu_cpu_opt != NULL)
-	mfpu_opt = &fpu_default;
-      else if (mcpu_fpu_opt != NULL && ARM_CPU_HAS_FEATURE (*mcpu_fpu_opt, arm_ext_v5))
-	mfpu_opt = &fpu_arch_vfp_v2;
+      if (!no_cpu_selected ())
+	selected_fpu = fpu_default;
       else
-	mfpu_opt = &fpu_arch_fpa;
+	selected_fpu = fpu_arch_fpa;
     }
 
 #ifdef CPU_DEFAULT
-  if (!mcpu_cpu_opt)
+  if (ARM_FEATURE_ZERO (selected_arch))
     {
-      mcpu_cpu_opt = &cpu_default;
-      selected_cpu = cpu_default;
+      selected_arch = cpu_default;
+      selected_cpu = selected_arch;
     }
-  else if (dyn_mcpu_ext_opt)
-    ARM_MERGE_FEATURE_SETS (selected_cpu, *mcpu_cpu_opt, *dyn_mcpu_ext_opt);
-  else
-    selected_cpu = *mcpu_cpu_opt;
+  ARM_MERGE_FEATURE_SETS (cpu_variant, selected_cpu, selected_fpu);
 #else
-  if (mcpu_cpu_opt && dyn_mcpu_ext_opt)
-    ARM_MERGE_FEATURE_SETS (selected_cpu, *mcpu_cpu_opt, *dyn_mcpu_ext_opt);
-  else if (mcpu_cpu_opt)
-    selected_cpu = *mcpu_cpu_opt;
+  /*  Autodection of feature mode: allow all features in cpu_variant but leave
+      selected_cpu unset.  It will be set in aeabi_set_public_attributes ()
+      after all instruction have been processed and we can decide what CPU
+      should be selected.  */
+  if (ARM_FEATURE_ZERO (selected_arch))
+    ARM_MERGE_FEATURE_SETS (cpu_variant, arm_arch_any, selected_fpu);
   else
-    mcpu_cpu_opt = &arm_arch_any;
+    ARM_MERGE_FEATURE_SETS (cpu_variant, selected_cpu, selected_fpu);
 #endif
 
-  ARM_MERGE_FEATURE_SETS (cpu_variant, *mcpu_cpu_opt, *mfpu_opt);
-  if (dyn_mcpu_ext_opt)
-    ARM_MERGE_FEATURE_SETS (cpu_variant, cpu_variant, *dyn_mcpu_ext_opt);
-
   autoselect_thumb_from_cpu_variant ();
 
   arm_arch_used = thumb_arch_used = arm_arch_none;
@@ -26444,7 +26467,7 @@ struct arm_long_option_table
 
 static bfd_boolean
 arm_parse_extension (const char *str, const arm_feature_set *opt_set,
-		     arm_feature_set **ext_set_p)
+		     arm_feature_set *ext_set)
 {
   /* We insist on extensions being specified in alphabetical order, and with
      extensions being added before being removed.  We achieve this by having
@@ -26456,12 +26479,6 @@ arm_parse_extension (const char *str, const arm_feature_set *opt_set,
   const arm_feature_set arm_any = ARM_ANY;
   int adding_value = -1;
 
-  if (!*ext_set_p)
-    {
-      *ext_set_p = XNEW (arm_feature_set);
-      **ext_set_p = arm_arch_none;
-    }
-
   while (str != NULL && *str != 0)
     {
       const char *ext;
@@ -26539,10 +26556,9 @@ arm_parse_extension (const char *str, const arm_feature_set *opt_set,
 
 	    /* Add or remove the extension.  */
 	    if (adding_value)
-	      ARM_MERGE_FEATURE_SETS (**ext_set_p, **ext_set_p,
-				      opt->merge_value);
+	      ARM_MERGE_FEATURE_SETS (*ext_set, *ext_set, opt->merge_value);
 	    else
-	      ARM_CLEAR_FEATURE (**ext_set_p, **ext_set_p, opt->clear_value);
+	      ARM_CLEAR_FEATURE (*ext_set, *ext_set, opt->clear_value);
 
 	    /* Allowing Thumb division instructions for ARMv7 in autodetection
 	       rely on this break so that duplicate extensions (extensions
@@ -26603,9 +26619,9 @@ arm_parse_cpu (const char *str)
     if (opt->name_len == len && strncmp (opt->name, str, len) == 0)
       {
 	mcpu_cpu_opt = &opt->value;
-	if (!dyn_mcpu_ext_opt)
-	  dyn_mcpu_ext_opt = XNEW (arm_feature_set);
-	*dyn_mcpu_ext_opt = opt->ext;
+	if (mcpu_ext_opt == NULL)
+	  mcpu_ext_opt = XNEW (arm_feature_set);
+	*mcpu_ext_opt = opt->ext;
 	mcpu_fpu_opt = &opt->default_fpu;
 	if (opt->canonical_name)
 	  {
@@ -26625,7 +26641,7 @@ arm_parse_cpu (const char *str)
 	  }
 
 	if (ext != NULL)
-	  return arm_parse_extension (ext, mcpu_cpu_opt, &dyn_mcpu_ext_opt);
+	  return arm_parse_extension (ext, mcpu_cpu_opt, mcpu_ext_opt);
 
 	return TRUE;
       }
@@ -26656,11 +26672,14 @@ arm_parse_arch (const char *str)
     if (opt->name_len == len && strncmp (opt->name, str, len) == 0)
       {
 	march_cpu_opt = &opt->value;
+	if (march_ext_opt == NULL)
+	  march_ext_opt = XNEW (arm_feature_set);
+	*march_ext_opt = arm_arch_none;
 	march_fpu_opt = &opt->default_fpu;
 	strcpy (selected_cpu_name, opt->name);
 
 	if (ext != NULL)
-	  return arm_parse_extension (ext, march_cpu_opt, &dyn_march_ext_opt);
+	  return arm_parse_extension (ext, march_cpu_opt, march_ext_opt);
 
 	return TRUE;
       }
@@ -27152,26 +27171,31 @@ aeabi_set_public_attributes (void)
 	ARM_MERGE_FEATURE_SETS (flags, flags, arm_ext_v4t);
 
       /* Code run during relaxation relies on selected_cpu being set.  */
+      ARM_CLEAR_FEATURE (flags_arch, flags, fpu_any);
+      flags_ext = arm_arch_none;
+      ARM_CLEAR_FEATURE (selected_arch, flags_arch, flags_ext);
+      selected_ext = flags_ext;
       selected_cpu = flags;
     }
   /* Otherwise, choose the architecture based on the capabilities of the
      requested cpu.  */
   else
-    flags = selected_cpu;
-  ARM_MERGE_FEATURE_SETS (flags, flags, *mfpu_opt);
+    {
+      ARM_MERGE_FEATURE_SETS (flags_arch, selected_arch, selected_ext);
+      ARM_CLEAR_FEATURE (flags_arch, flags_arch, fpu_any);
+      flags_ext = selected_ext;
+      flags = selected_cpu;
+    }
+  ARM_MERGE_FEATURE_SETS (flags, flags, selected_fpu);
 
   /* Allow the user to override the reported architecture.  */
-  if (object_arch)
+  if (!ARM_FEATURE_ZERO (selected_object_arch))
     {
-      ARM_CLEAR_FEATURE (flags_arch, *object_arch, fpu_any);
+      ARM_CLEAR_FEATURE (flags_arch, selected_object_arch, fpu_any);
       flags_ext = arm_arch_none;
     }
   else
-    {
-      ARM_CLEAR_FEATURE (flags_arch, flags, fpu_any);
-      flags_ext = dyn_mcpu_ext_opt ? *dyn_mcpu_ext_opt : arm_arch_none;
-      skip_exact_match = ARM_FEATURE_EQUAL (selected_cpu, arm_arch_any);
-    }
+    skip_exact_match = ARM_FEATURE_EQUAL (selected_cpu, arm_arch_any);
 
   /* When this function is run again after relaxation has happened there is no
      way to determine whether an architecture or CPU was specified by the user:
@@ -27212,7 +27236,7 @@ aeabi_set_public_attributes (void)
     aeabi_set_attribute_int (Tag_CPU_arch_profile, profile);
 
   /* Tag_DSP_extension.  */
-  if (dyn_mcpu_ext_opt && ARM_CPU_HAS_FEATURE (*dyn_mcpu_ext_opt, arm_ext_dsp))
+  if (ARM_CPU_HAS_FEATURE (selected_ext, arm_ext_dsp))
     aeabi_set_attribute_int (Tag_DSP_extension, 1);
 
   ARM_CLEAR_FEATURE (flags_arch, flags, fpu_any);
@@ -27335,10 +27359,10 @@ void
 arm_md_post_relax (void)
 {
   aeabi_set_public_attributes ();
-  XDELETE (dyn_mcpu_ext_opt);
-  dyn_mcpu_ext_opt = NULL;
-  XDELETE (dyn_march_ext_opt);
-  dyn_march_ext_opt = NULL;
+  XDELETE (mcpu_ext_opt);
+  mcpu_ext_opt = NULL;
+  XDELETE (march_ext_opt);
+  march_ext_opt = NULL;
 }
 
 /* Add the default contents for the .ARM.attributes section.  */
@@ -27372,11 +27396,9 @@ s_arm_cpu (int ignored ATTRIBUTE_UNUSED)
   for (opt = arm_cpus + 1; opt->name != NULL; opt++)
     if (streq (opt->name, name))
       {
-	mcpu_cpu_opt = &opt->value;
-	if (!dyn_mcpu_ext_opt)
-	  dyn_mcpu_ext_opt = XNEW (arm_feature_set);
-	*dyn_mcpu_ext_opt = opt->ext;
-	ARM_MERGE_FEATURE_SETS (selected_cpu, *mcpu_cpu_opt, *dyn_mcpu_ext_opt);
+	selected_arch = opt->value;
+	selected_ext = opt->ext;
+	ARM_MERGE_FEATURE_SETS (selected_cpu, selected_arch, selected_ext);
 	if (opt->canonical_name)
 	  strcpy (selected_cpu_name, opt->canonical_name);
 	else
@@ -27387,9 +27409,8 @@ s_arm_cpu (int ignored ATTRIBUTE_UNUSED)
 
 	    selected_cpu_name[i] = 0;
 	  }
-	ARM_MERGE_FEATURE_SETS (cpu_variant, *mcpu_cpu_opt, *mfpu_opt);
-	if (dyn_mcpu_ext_opt)
-	  ARM_MERGE_FEATURE_SETS (cpu_variant, cpu_variant, *dyn_mcpu_ext_opt);
+	ARM_MERGE_FEATURE_SETS (cpu_variant, selected_cpu, selected_fpu);
+
 	*input_line_pointer = saved_char;
 	demand_empty_rest_of_line ();
 	return;
@@ -27418,12 +27439,11 @@ s_arm_arch (int ignored ATTRIBUTE_UNUSED)
   for (opt = arm_archs + 1; opt->name != NULL; opt++)
     if (streq (opt->name, name))
       {
-	mcpu_cpu_opt = &opt->value;
-	XDELETE (dyn_mcpu_ext_opt);
-	dyn_mcpu_ext_opt = NULL;
-	selected_cpu = *mcpu_cpu_opt;
+	selected_arch = opt->value;
+	selected_ext = arm_arch_none;
+	selected_cpu = selected_arch;
 	strcpy (selected_cpu_name, opt->name);
-	ARM_MERGE_FEATURE_SETS (cpu_variant, selected_cpu, *mfpu_opt);
+	ARM_MERGE_FEATURE_SETS (cpu_variant, selected_cpu, selected_fpu);
 	*input_line_pointer = saved_char;
 	demand_empty_rest_of_line ();
 	return;
@@ -27453,7 +27473,7 @@ s_arm_object_arch (int ignored ATTRIBUTE_UNUSED)
   for (opt = arm_archs + 1; opt->name != NULL; opt++)
     if (streq (opt->name, name))
       {
-	object_arch = &opt->value;
+	selected_object_arch = opt->value;
 	*input_line_pointer = saved_char;
 	demand_empty_rest_of_line ();
 	return;
@@ -27470,7 +27490,6 @@ static void
 s_arm_arch_extension (int ignored ATTRIBUTE_UNUSED)
 {
   const struct arm_option_extension_value_table *opt;
-  const arm_feature_set arm_any = ARM_ANY;
   char saved_char;
   char *name;
   int adding_value = 1;
@@ -27496,9 +27515,9 @@ s_arm_arch_extension (int ignored ATTRIBUTE_UNUSED)
 	for (i = 0; i < nb_allowed_archs; i++)
 	  {
 	    /* Empty entry.  */
-	    if (ARM_FEATURE_EQUAL (opt->allowed_archs[i], arm_any))
+	    if (ARM_CPU_IS_ANY (opt->allowed_archs[i]))
 	      continue;
-	    if (ARM_FSET_CPU_SUBSET (opt->allowed_archs[i], *mcpu_cpu_opt))
+	    if (ARM_FSET_CPU_SUBSET (opt->allowed_archs[i], selected_arch))
 	      break;
 	  }
 
@@ -27509,20 +27528,14 @@ s_arm_arch_extension (int ignored ATTRIBUTE_UNUSED)
 	    break;
 	  }
 
-	if (!dyn_mcpu_ext_opt)
-	  {
-	    dyn_mcpu_ext_opt = XNEW (arm_feature_set);
-	    *dyn_mcpu_ext_opt = arm_arch_none;
-	  }
 	if (adding_value)
-	  ARM_MERGE_FEATURE_SETS (*dyn_mcpu_ext_opt, *dyn_mcpu_ext_opt,
+	  ARM_MERGE_FEATURE_SETS (selected_ext, selected_ext,
 				  opt->merge_value);
 	else
-	  ARM_CLEAR_FEATURE (*dyn_mcpu_ext_opt, *dyn_mcpu_ext_opt,
-			     opt->clear_value);
+	  ARM_CLEAR_FEATURE (selected_ext, selected_ext, opt->clear_value);
 
-	ARM_MERGE_FEATURE_SETS (selected_cpu, *mcpu_cpu_opt, *dyn_mcpu_ext_opt);
-	ARM_MERGE_FEATURE_SETS (cpu_variant, selected_cpu, *mfpu_opt);
+	ARM_MERGE_FEATURE_SETS (selected_cpu, selected_arch, selected_ext);
+	ARM_MERGE_FEATURE_SETS (cpu_variant, selected_cpu, selected_fpu);
 	*input_line_pointer = saved_char;
 	demand_empty_rest_of_line ();
 	/* Allowing Thumb division instructions for ARMv7 in autodetection rely
@@ -27557,10 +27570,13 @@ s_arm_fpu (int ignored ATTRIBUTE_UNUSED)
   for (opt = arm_fpus; opt->name != NULL; opt++)
     if (streq (opt->name, name))
       {
-	mfpu_opt = &opt->value;
-	ARM_MERGE_FEATURE_SETS (cpu_variant, *mcpu_cpu_opt, *mfpu_opt);
-	if (dyn_mcpu_ext_opt)
-	  ARM_MERGE_FEATURE_SETS (cpu_variant, cpu_variant, *dyn_mcpu_ext_opt);
+	selected_fpu = opt->value;
+#ifndef CPU_DEFAULT
+	if (no_cpu_selected ())
+	  ARM_MERGE_FEATURE_SETS (cpu_variant, arm_arch_any, selected_fpu);
+	else
+#endif
+	  ARM_MERGE_FEATURE_SETS (cpu_variant, selected_cpu, selected_fpu);
 	*input_line_pointer = saved_char;
 	demand_empty_rest_of_line ();
 	return;