[arm] Simplify run-time CPU selection.

src/flag-definitions.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // This file defines all of the flags.  It is separated into different section,
 // for Debug, Release, Logging and Profiling, etc.  To add a new flag, find the
 // correct section, and use one of the DEFINE_ macros, without a trailing ';'.
 //
 // This include does not have a guard, because it is a template-style include,
 // which can be included multiple times in different modes.  It expects to have
@@ skipping 101 matching lines @@
   bool has_value;
   bool value;
 };
 #endif
 
 #ifdef DEBUG
 #define DEBUG_BOOL true
 #else
 #define DEBUG_BOOL false
 #endif
-#if (defined CAN_USE_VFP3_INSTRUCTIONS) || !(defined ARM_TEST_NO_FEATURE_PROBE)
-#define ENABLE_VFP3_DEFAULT true
+
+// Supported ARM configurations are:
+//  "armv6":       ARMv6 + VFPv2
+//  "armv7":       ARMv7 + VFPv3-D32 + NEON
+//  "armv7+sudiv": ARMv7 + VFPv4-D32 + NEON + SUDIV
+//  "armv8":       ARMv8 (including all of the above)
+#if !defined(ARM_TEST_NO_FEATURE_PROBE) ||                            \
+    (defined(CAN_USE_ARMV8_INSTRUCTIONS) &&                           \
+     defined(CAN_USE_ARMV7_INSTRUCTIONS) && defined(CAN_USE_SUDIV) && \
+     defined(CAN_USE_NEON) && defined(CAN_USE_VFP3_INSTRUCTIONS))
+#define ARM_ARCH_DEFAULT "armv8"
+#elif defined(CAN_USE_ARMV7_INSTRUCTIONS) && defined(CAN_USE_SUDIV) && \
+    defined(CAN_USE_NEON) && defined(CAN_USE_VFP3_INSTRUCTIONS)
+#define ARM_ARCH_DEFAULT "armv7+sudiv"
+#elif defined(CAN_USE_ARMV7_INSTRUCTIONS) && defined(CAN_USE_NEON) && \
+    defined(CAN_USE_VFP3_INSTRUCTIONS)
+#define ARM_ARCH_DEFAULT "armv7"
 #else
-#define ENABLE_VFP3_DEFAULT false
+#define ARM_ARCH_DEFAULT "armv6"
 #endif
-#if (defined CAN_USE_ARMV7_INSTRUCTIONS) || !(defined ARM_TEST_NO_FEATURE_PROBE)
-#define ENABLE_ARMV7_DEFAULT true
-#else
-#define ENABLE_ARMV7_DEFAULT false
-#endif
-#if (defined CAN_USE_ARMV8_INSTRUCTIONS) || !(defined ARM_TEST_NO_FEATURE_PROBE)
-#define ENABLE_ARMV8_DEFAULT true
-#else
-#define ENABLE_ARMV8_DEFAULT false
-#endif
-#if (defined CAN_USE_VFP32DREGS) || !(defined ARM_TEST_NO_FEATURE_PROBE)
-#define ENABLE_32DREGS_DEFAULT true
-#else
-#define ENABLE_32DREGS_DEFAULT false
-#endif
-#if (defined CAN_USE_NEON) || !(defined ARM_TEST_NO_FEATURE_PROBE)
-# define ENABLE_NEON_DEFAULT true
-#else
-# define ENABLE_NEON_DEFAULT false
-#endif
+
 #ifdef V8_OS_WIN
 # define ENABLE_LOG_COLOUR false
 #else
 # define ENABLE_LOG_COLOUR true
 #endif
 
 #define DEFINE_BOOL(nam, def, cmt) FLAG(BOOL, bool, nam, def, cmt)
 #define DEFINE_BOOL_READONLY(nam, def, cmt) \
   FLAG_READONLY(BOOL, bool, nam, def, cmt)
 #define DEFINE_MAYBE_BOOL(nam, cmt) \
@@ skipping 397 matching lines @@
             "enable use of SSE4.1 instructions if available")
 DEFINE_BOOL(enable_sahf, true,
             "enable use of SAHF instruction if available (X64 only)")
 DEFINE_BOOL(enable_avx, true, "enable use of AVX instructions if available")
 DEFINE_BOOL(enable_fma3, true, "enable use of FMA3 instructions if available")
 DEFINE_BOOL(enable_bmi1, true, "enable use of BMI1 instructions if available")
 DEFINE_BOOL(enable_bmi2, true, "enable use of BMI2 instructions if available")
 DEFINE_BOOL(enable_lzcnt, true, "enable use of LZCNT instruction if available")
 DEFINE_BOOL(enable_popcnt, true,
             "enable use of POPCNT instruction if available")
-DEFINE_BOOL(enable_vfp3, ENABLE_VFP3_DEFAULT,
-            "enable use of VFP3 instructions if available")
-DEFINE_BOOL(enable_armv7, ENABLE_ARMV7_DEFAULT,
-            "enable use of ARMv7 instructions if available (ARM only)")
-DEFINE_BOOL(enable_armv8, ENABLE_ARMV8_DEFAULT,
-            "enable use of ARMv8 instructions if available (ARM 32-bit only)")
-DEFINE_BOOL(enable_neon, ENABLE_NEON_DEFAULT,
-            "enable use of NEON instructions if available (ARM only)")
-DEFINE_BOOL(enable_sudiv, true,
-            "enable use of SDIV and UDIV instructions if available (ARM only)")
+DEFINE_STRING(arm_arch, ARM_ARCH_DEFAULT,
+              "generate instructions for the selected ARM architecture if "
+              "available: armv6, armv7, armv7+sudiv or armv8")
 DEFINE_BOOL(enable_movw_movt, false,
-            "enable loading 32-bit constant by means of movw/movt "
-            "instruction pairs (ARM only)")
-DEFINE_BOOL(enable_32dregs, ENABLE_32DREGS_DEFAULT,
-            "enable use of d16-d31 registers on ARM - this requires VFP3")
+            "prefer to load 32-bit constants using movw/movt instruction pairs "
+            "(ARM only)")
 DEFINE_BOOL(enable_vldr_imm, false,
             "enable use of constant pools for double immediate (ARM only)")
 DEFINE_BOOL(force_long_branches, false,
             "force all emitted branches to be in long mode (MIPS/PPC only)")
 DEFINE_STRING(mcpu, "auto", "enable optimization for specific cpu")
 
+// Deprecated ARM flags (replaced by arm_arch).
+DEFINE_MAYBE_BOOL(enable_armv7, "deprecated (use --arm_arch instead)")
+DEFINE_MAYBE_BOOL(enable_vfp3, "deprecated (use --arm_arch instead)")
+DEFINE_MAYBE_BOOL(enable_32dregs, "deprecated (use --arm_arch instead)")
+DEFINE_MAYBE_BOOL(enable_neon, "deprecated (use --arm_arch instead)")
+DEFINE_MAYBE_BOOL(enable_sudiv, "deprecated (use --arm_arch instead)")
+DEFINE_MAYBE_BOOL(enable_armv8, "deprecated (use --arm_arch instead)")
+
 // regexp-macro-assembler-*.cc
 DEFINE_BOOL(enable_regexp_unaligned_accesses, true,
             "enable unaligned accesses for the regexp engine")
 
-DEFINE_IMPLICATION(enable_armv8, enable_vfp3)
-DEFINE_IMPLICATION(enable_armv8, enable_neon)
-DEFINE_IMPLICATION(enable_armv8, enable_32dregs)
-DEFINE_IMPLICATION(enable_armv8, enable_sudiv)
-
 // bootstrapper.cc
 DEFINE_STRING(expose_natives_as, NULL, "expose natives in global object")
 DEFINE_STRING(expose_debug_as, NULL, "expose debug in global object")
 DEFINE_BOOL(expose_free_buffer, false, "expose freeBuffer extension")
 DEFINE_BOOL(expose_gc, false, "expose gc extension")
 DEFINE_STRING(expose_gc_as, NULL,
               "expose gc extension under the specified name")
 DEFINE_IMPLICATION(expose_gc_as, expose_gc)
 DEFINE_BOOL(expose_externalize_string, false,
             "expose externalize string extension")
@@ skipping 609 matching lines @@
 #undef DEFINE_ALIAS_FLOAT
 #undef DEFINE_ALIAS_ARGS
 
 #undef FLAG_MODE_DECLARE
 #undef FLAG_MODE_DEFINE
 #undef FLAG_MODE_DEFINE_DEFAULTS
 #undef FLAG_MODE_META
 #undef FLAG_MODE_DEFINE_IMPLICATIONS
 
 #undef COMMA