arm: Fix an incorrect warning when -mcpu=cortex-a55 is used with -mfloat-abi=soft

When a CPU such as cortex-a55 is used with the soft-float ABI variant,
the compiler is incorrectly issuing a warning about a mismatch between
the architecture (generated internally) and the CPU.  This is not
expected or intended.

The problem stems from the fact that we generate (correctly) an
architecture for a soft-float compilation, but then try to compare it
against the one recorded for the CPU.  Normally we strip out the
floating point information before doing that comparison, but we
currently only do that for the features that can be affected by the
-mfpu option.  For a soft-float environment we also need to strip out
any bits that depend on having floating-point present.

So this patch implements that and does a bit of housekeeping at the
same time:

- in arm-cpus.in it is not necessary for a CPU to specify both
  +dotprod and +simd in its architecture specification, since +dotprod
  implies +simd.

- I've refactored the ALL_SIMD fgroup in arm-cpus.in to create a new
  subgroup ALL_SIMD_EXTERNAL and containing the bits that were
  previously added directly to ALL_SIMD.  Similarly, I've added an
  ALL_FPU_EXTERNAL subgroup.

- in arm.c rename fpu_bitlist and all_fpubits to fpu_bitlist_internal
  and all_fpubits_internal for consistency with the fgroup bits which
  they contain.

	* config/arm/arm-cpus.in (ALL_SIMD_EXTERNAL): New fgroup.
	(ALL_SIMD): Use it.
	(ALL_FPU_EXTERNAL): New fgroup.
	(ALL_FP): Use it.
	(cortex-a55, cortex-a75, cortex-a76, cortex-a76ae): Remove redundant
	+simd from architecture specification.
	(cortex-a77, neoverse-n1, cortex-a75.cortex-a55): Likewise.
	* config/arm/arm.c (isa_all_fpubits, fpu_bitlist): Rename to ...
	(isa_all_fpubits_internal, fpu_bitlist_internal): ... these.
	(isa_all_fpbits): New bitmap.
	(arm_option_override): Initialize it.
	(arm_configure_build_target): If the target isa does not have any
	FP enabled, do not warn about mismatches in FP-related feature bits.

From-SVN: r279219

gcc/ChangeLog

+2019-12-11  Richard Earnshaw  <rearnsha@arm.com>
+
+	* config/arm/arm-cpus.in (ALL_SIMD_EXTERNAL): New fgroup.
+	(ALL_SIMD): Use it.
+	(ALL_FPU_EXTERNAL): New fgroup.
+	(ALL_FP): Use it.
+	(cortex-a55, cortex-a75, cortex-a76, cortex-a76ae): Remove redundant
+	+simd from architecture specification.
+	(cortex-a77, neoverse-n1, cortex-a75.cortex-a55): Likewise.
+	* config/arm/arm.c (isa_all_fpubits, fpu_bitlist): Rename to ...
+	(isa_all_fpubits_internal, fpu_bitlist_internal): ... these.
+	(isa_all_fpbits): New bitmap.
+	(arm_option_override): Initialize it.
+	(arm_configure_build_target): If the target isa does not have any
+	FP enabled, do not warn about mismatches in FP-related feature bits.
+
 2019-12-11  Stam Markianos-Wright  <stam.markianos-wright@arm.com>
 	* real.c (struct arm_bfloat_half_format,

gcc/config/arm/arm-cpus.in

@@ -213,15 +213,18 @@ define fgroup ALL_CRYPTO	crypto
 # strip off 32 D-registers, but does not remove support for
 # double-precision FP.
 define fgroup ALL_SIMD_INTERNAL	fp_d32 neon ALL_CRYPTO
-define fgroup ALL_SIMD	ALL_SIMD_INTERNAL dotprod fp16fml
+define fgroup ALL_SIMD_EXTERNAL dotprod fp16fml
+define fgroup ALL_SIMD	ALL_SIMD_INTERNAL ALL_SIMD_EXTERNAL
 
 # List of all FPU bits to strip out if -mfpu is used to override the
 # default.  fp16 is deliberately missing from this list.
 define fgroup ALL_FPU_INTERNAL	vfpv2 vfpv3 vfpv4 fpv5 fp16conv fp_dbl ALL_SIMD_INTERNAL
-
 # Similarly, but including fp16 and other extensions that aren't part of
 # -mfpu support.
-define fgroup ALL_FP	fp16 ALL_FPU_INTERNAL
+define fgroup ALL_FPU_EXTERNAL fp16
+
+# Everything related to the FPU extensions (FP or SIMD).
+define fgroup ALL_FP	ALL_FPU_EXTERNAL ALL_FPU_INTERNAL ALL_SIMD
 
 define fgroup ARMv4       armv4 notm
 define fgroup ARMv4t      ARMv4 thumb
@@ -1301,7 +1304,7 @@ begin cpu cortex-a55
  cname cortexa55
  tune for cortex-a53
  tune flags LDSCHED
- architecture armv8.2-a+fp16+dotprod+simd
+ architecture armv8.2-a+fp16+dotprod
  option crypto add FP_ARMv8 CRYPTO
  option nofp remove ALL_FP
  costs cortex_a53
@@ -1313,7 +1316,7 @@ begin cpu cortex-a75
  cname cortexa75
  tune for cortex-a57
  tune flags LDSCHED
- architecture armv8.2-a+fp16+dotprod+simd
+ architecture armv8.2-a+fp16+dotprod
  option crypto add FP_ARMv8 CRYPTO
  costs cortex_a73
  vendor 41
@@ -1324,7 +1327,7 @@ begin cpu cortex-a76
  cname cortexa76
  tune for cortex-a57
  tune flags LDSCHED
- architecture armv8.2-a+fp16+dotprod+simd
+ architecture armv8.2-a+fp16+dotprod
  option crypto add FP_ARMv8 CRYPTO
  costs cortex_a57
  vendor 41
@@ -1335,7 +1338,7 @@ begin cpu cortex-a76ae
  cname cortexa76ae
  tune for cortex-a57
  tune flags LDSCHED
- architecture armv8.2-a+fp16+dotprod+simd
+ architecture armv8.2-a+fp16+dotprod
  option crypto add FP_ARMv8 CRYPTO
  costs cortex_a57
  vendor 41
@@ -1346,7 +1349,7 @@ begin cpu cortex-a77
  cname cortexa77
  tune for cortex-a57
  tune flags LDSCHED
- architecture armv8.2-a+fp16+dotprod+simd
+ architecture armv8.2-a+fp16+dotprod
  option crypto add FP_ARMv8 CRYPTO
  costs cortex_a57
  vendor 41
@@ -1358,7 +1361,7 @@ begin cpu neoverse-n1
  alias !ares
  tune for cortex-a57
  tune flags LDSCHED
- architecture armv8.2-a+fp16+dotprod+simd
+ architecture armv8.2-a+fp16+dotprod
  option crypto add FP_ARMv8 CRYPTO
  costs cortex_a57
  vendor 41
@@ -1370,7 +1373,7 @@ begin cpu cortex-a75.cortex-a55
  cname cortexa75cortexa55
  tune for cortex-a53
  tune flags LDSCHED
- architecture armv8.2-a+fp16+dotprod+simd
+ architecture armv8.2-a+fp16+dotprod
  option crypto add FP_ARMv8 CRYPTO
  costs cortex_a73
 end cpu cortex-a75.cortex-a55
@@ -1379,7 +1382,7 @@ begin cpu cortex-a76.cortex-a55
  cname cortexa76cortexa55
  tune for cortex-a53
  tune flags LDSCHED
- architecture armv8.2-a+fp16+dotprod+simd
+ architecture armv8.2-a+fp16+dotprod
  option crypto add FP_ARMv8 CRYPTO
  costs cortex_a57
 end cpu cortex-a76.cortex-a55

gcc/config/arm/arm.c

@@ -3109,7 +3109,8 @@ arm_option_override_internal (struct gcc_options *opts,
 #endif
 }
-static sbitmap isa_all_fpubits;
+static sbitmap isa_all_fpubits_internal;
+static sbitmap isa_all_fpbits;
 static sbitmap isa_quirkbits;
 /* Configure a build target TARGET from the user-specified options OPTS and
@@ -3176,7 +3177,12 @@ arm_configure_build_target (struct arm_build_target *target,
 	  /* Ignore any bits that are quirk bits.  */
 	  bitmap_and_compl (isa_delta, isa_delta, isa_quirkbits);
 	  /* Ignore (for now) any bits that might be set by -mfpu.  */
-	  bitmap_and_compl (isa_delta, isa_delta, isa_all_fpubits);
+	  bitmap_and_compl (isa_delta, isa_delta, isa_all_fpubits_internal);
+
+	  /* And if the target ISA lacks floating point, ignore any
+	     extensions that depend on that.  */
+	  if (!bitmap_bit_p (target->isa, isa_bit_vfpv2))
+	    bitmap_and_compl (isa_delta, isa_delta, isa_all_fpbits);
 	  if (!bitmap_empty_p (isa_delta))
 	    {
@@ -3335,7 +3341,7 @@ arm_configure_build_target (struct arm_build_target *target,
       auto_sbitmap fpu_bits (isa_num_bits);
       arm_initialize_isa (fpu_bits, arm_selected_fpu->isa_bits);
-      bitmap_and_compl (target->isa, target->isa, isa_all_fpubits);
+      bitmap_and_compl (target->isa, target->isa, isa_all_fpubits_internal);
       bitmap_ior (target->isa, target->isa, fpu_bits);
     }
@@ -3361,16 +3367,20 @@ arm_configure_build_target (struct arm_build_target *target,
 static void
 arm_option_override (void)
 {
-  static const enum isa_feature fpu_bitlist[]
+  static const enum isa_feature fpu_bitlist_internal[]
     = { ISA_ALL_FPU_INTERNAL, isa_nobit };
+  static const enum isa_feature fp_bitlist[]
+    = { ISA_ALL_FP, isa_nobit };
   static const enum isa_feature quirk_bitlist[] = { ISA_ALL_QUIRKS, isa_nobit};
   cl_target_option opts;
   isa_quirkbits = sbitmap_alloc (isa_num_bits);
   arm_initialize_isa (isa_quirkbits, quirk_bitlist);
-  isa_all_fpubits = sbitmap_alloc (isa_num_bits);
-  arm_initialize_isa (isa_all_fpubits, fpu_bitlist);
+  isa_all_fpubits_internal = sbitmap_alloc (isa_num_bits);
+  isa_all_fpbits = sbitmap_alloc (isa_num_bits);
+  arm_initialize_isa (isa_all_fpubits_internal, fpu_bitlist_internal);
+  arm_initialize_isa (isa_all_fpbits, fp_bitlist);
   arm_active_target.isa = sbitmap_alloc (isa_num_bits);
@@ -27258,7 +27268,7 @@ arm_print_asm_arch_directives ()
 	     don't print anything if all the bits are part of the
 	     FPU specification.  */
 	  if (bitmap_subset_p (opt_bits, arm_active_target.isa)
-	      && !bitmap_subset_p (opt_bits, isa_all_fpubits))
+	      && !bitmap_subset_p (opt_bits, isa_all_fpubits_internal))
 	    asm_fprintf (asm_out_file, "\t.arch_extension %s\n", opt->name);
 	}
     }
@@ -31771,7 +31781,7 @@ arm_identify_fpu_from_isa (sbitmap isa)
   auto_sbitmap fpubits (isa_num_bits);
   auto_sbitmap cand_fpubits (isa_num_bits);
-  bitmap_and (fpubits, isa, isa_all_fpubits);
+  bitmap_and (fpubits, isa, isa_all_fpubits_internal);
   /* If there are no ISA feature bits relating to the FPU, we must be
      doing soft-float.  */
@@ -31831,7 +31841,7 @@ arm_declare_function_name (FILE *stream, const char *name, tree decl)
 		{
 		  arm_initialize_isa (opt_bits, opt->isa_bits);
 		  if (bitmap_subset_p (opt_bits, arm_active_target.isa)
-		      && !bitmap_subset_p (opt_bits, isa_all_fpubits))
+		      && !bitmap_subset_p (opt_bits, isa_all_fpubits_internal))
 		    asm_fprintf (asm_out_file, "\t.arch_extension %s\n",
 				 opt->name);
 		}
@@ -32504,28 +32514,28 @@ arm_test_cpu_arch_data (void)
 static void
 arm_test_fpu_data (void)
 {
-  auto_sbitmap isa_all_fpubits (isa_num_bits);
+  auto_sbitmap isa_all_fpubits_internal (isa_num_bits);
   auto_sbitmap fpubits (isa_num_bits);
   auto_sbitmap tmpset (isa_num_bits);
-  static const enum isa_feature fpu_bitlist[]
+  static const enum isa_feature fpu_bitlist_internal[]
     = { ISA_ALL_FPU_INTERNAL, isa_nobit };
-  arm_initialize_isa (isa_all_fpubits, fpu_bitlist);
+  arm_initialize_isa (isa_all_fpubits_internal, fpu_bitlist_internal);
   for (unsigned int i = 0; i < TARGET_FPU_auto; i++)
   {
     arm_initialize_isa (fpubits, all_fpus[i].isa_bits);
-    bitmap_and_compl (tmpset, isa_all_fpubits, fpubits);
-    bitmap_clear (isa_all_fpubits);
-    bitmap_copy (isa_all_fpubits, tmpset);
+    bitmap_and_compl (tmpset, isa_all_fpubits_internal, fpubits);
+    bitmap_clear (isa_all_fpubits_internal);
+    bitmap_copy (isa_all_fpubits_internal, tmpset);
   }
-  if (!bitmap_empty_p (isa_all_fpubits))
+  if (!bitmap_empty_p (isa_all_fpubits_internal))
     {
 	fprintf (stderr, "Error: found feature bits in the ALL_FPU_INTERAL"
 			 " group that are not defined by any FPU.\n"
 			 "       Check your arm-cpus.in.\n");
-	ASSERT_TRUE (bitmap_empty_p (isa_all_fpubits));
+	ASSERT_TRUE (bitmap_empty_p (isa_all_fpubits_internal));
     }
 }