[arm] Rework arm-common to use new feature bits.

This converts the recently added implicit -mthumb support code to use
the new data structures.  Since we have a very simple query and no
initialized copies of the sbitmaps, for now we simply scan the list of
features to look for the one of interest.

	* arm-opts.h (struct arm_arch_core_flag): Add new field ISA.
	Initialize it.
   	(arm_arch_core_flag): Delete flags field.
    	(arm_arch_core_flags): Don't initialize flags field.
 	* common/config/arm/arm-common.c (check_isa_bits_for): New function.
	(arm_target_thumb_only): Use new isa bits arrays.

From-SVN: r243704

gcc/ChangeLog

 2016-12-15  Richard Earnshaw  <rearnsha@arm.com>
 
+	* arm-opts.h (struct arm_arch_core_flag): Add new field ISA.
+	Initialize it.
+   	(arm_arch_core_flag): Delete flags field.
+    	(arm_arch_core_flags): Don't initialize flags field.
+ 	* common/config/arm/arm-common.c (check_isa_bits_for): New function.
+	(arm_target_thumb_only): Use new isa bits arrays.
+
+2016-12-15  Richard Earnshaw  <rearnsha@arm.com>
+
 	* arm-protos.h (insn_flags): Delete declaration.
 	(arm_arch7ve): Declare.
 	* arm.c (insn_flags): Delete.

gcc/common/config/arm/arm-common.c

@@ -101,23 +101,37 @@ arm_rewrite_mcpu (int argc, const char **argv)
 struct arm_arch_core_flag
 {
   const char *const name;
-  const arm_feature_set flags;
+  const enum isa_feature isa_bits[isa_num_bits];
 };
 
 static const struct arm_arch_core_flag arm_arch_core_flags[] =
 {
 #undef ARM_CORE
 #define ARM_CORE(NAME, X, IDENT, TUNE_FLAGS, ARCH, ISA, FLAGS, COSTS)	\
-  {NAME, FLAGS},
+  {NAME, {ISA isa_nobit}},
 #include "config/arm/arm-cores.def"
 #undef ARM_CORE
 #undef ARM_ARCH
 #define ARM_ARCH(NAME, CORE, TUNE_FLAGS, ARCH, ISA, FLAGS)	\
-  {NAME, FLAGS},
+  {NAME, {ISA isa_nobit}},
 #include "config/arm/arm-arches.def"
 #undef ARM_ARCH
 };
 
+/* Scan over a raw feature array BITS checking for BIT being present.
+   This is slower than the normal bitmask checks, but we would spend longer
+   initializing that than doing the check this way.  Returns true iff
+   BIT is found.  */
+static bool
+check_isa_bits_for (const enum isa_feature* bits, enum isa_feature bit)
+{
+  while (*bits != isa_nobit)
+    if (*bits++ == bit)
+      return true;
+
+  return false;
+}
+
 /* Called by the driver to check whether the target denoted by current
    command line options is a Thumb-only target.  ARGV is an array of
    -march and -mcpu values (ie. it contains the rhs after the equal
@@ -132,7 +146,8 @@ arm_target_thumb_only (int argc, const char **argv)
     {
       for (opt = 0; opt < (ARRAY_SIZE (arm_arch_core_flags)); opt++)
 	if ((strcmp (argv[argc - 1], arm_arch_core_flags[opt].name) == 0)
-	    && !ARM_FSET_HAS_CPU1(arm_arch_core_flags[opt].flags, FL_NOTM))
+	    && !check_isa_bits_for (arm_arch_core_flags[opt].isa_bits,
+				    isa_bit_notm))
 	  return "-mthumb";
 
       return NULL;

gcc/config/arm/arm-opts.h

@@ -26,6 +26,7 @@
 #define ARM_OPTS_H
 
 #include "arm-flags.h"
+#include "arm-isa.h"
 
 /* The various ARM cores.  */
 enum processor_type