ARM JIT: use static configuration

The output of "/proc/cpuinfo" seems wrong for a Raspberry Pi running
the latest Raspian, because it claims ARMv6-compatible but also claims
"thumb" as a feature and 7 as the CPU architecture. Use the C compiler's
configuraton, instead, which is relatively straightforward and drops
code that will turn out to be dead.

src/racket/src/lightning/arm/asm-common.h

@@ -65,6 +65,7 @@ struct jit_local_state {
     jit_insn	*thumb;
 };
 
+#ifdef JIT_ARM_DYNAMIC_CPU
 struct {
     _ui		version		: 4;
     _ui		extend		: 1;
@@ -74,6 +75,8 @@ struct {
     _ui		neon		: 1;
     _ui		abi		: 2;
 } jit_cpu;
+#endif
+
 struct {
     /* prevent using thumb instructions that set flags? */
     _ui		no_set_flags	: 1;

src/racket/src/lightning/arm/asm.h

@@ -103,9 +103,79 @@ typedef enum {
 /* match vfpv3 result */
 #define NAN_TO_INT_IS_ZERO		1
 
-#define jit_thumb_p()			jit_cpu.thumb
+#if defined(__ARM_ARCH_4__)
-#define jit_armv6_p()			(jit_cpu.version >= 6)
+# define JIT_ARM_VERSION 4
-#define jit_advsimd_p()			((jit_cpu.version >= 7) && jit_thumb_p())
+#elif defined(__ARM_ARCH_4T__)
+# define JIT_ARM_THUMB 1
+# define JIT_ARM_VERSION 4
+#elif (defined(__ARM_ARCH_5T__) || defined(__ARM_ARCH_5__))
+# define JIT_ARM_THUMB 1
+# define JIT_ARM_VERSION 5
+#elif (defined(__ARM_ARCH_5TE__) || defined(__ARM_ARCH_5TEJ__))
+# define JIT_ARM_THUMB 1
+# define JIT_ARM_VERSION 5
+# define JIT_ARM_EXTENDED 1
+#elif defined(__ARM_ARCH_6__) || defined(__ARM_ARCH_6K__)
+# define JIT_ARM_VERSION 6
+#elif defined(__ARM_ARCH_6T__) || defined(__ARM_ARCH_6T2__)
+# define JIT_ARM_THUMB 2
+# define JIT_ARM_VERSION 6
+#elif (defined(__ARM_ARCH_7A__) || defined(__ARM_ARCH_7R__) || defined(__ARM_ARCH_7M__) || defined(__ARM_ARCH_7__))
+# define JIT_ARM_THUMB 2
+# define JIT_ARM_VERSION 7
+# if defined(__ARM_ARCH_7R__)
+#  define JIT_ARM_REALTIME 1
+# endif
+#else
+# define JIT_ARM_VERSION 4
+#endif
+
+#if defined(__ARM_PCS_VFP) || defined(__VFP_FP__)
+# define JIT_ARM_VFP 1
+#endif
+
+#if defined(__ARM_NEON__)
+# define JIT_ARM_NEON 1
+#endif
+
+#ifndef JIT_ARM_THUMB
+# define JIT_ARM_THUMB 0
+#endif
+
+#ifndef JIT_ARM_NEON
+# define JIT_ARM_NEON 0
+#endif
+
+#ifndef JIT_ARM_EXTENDED
+# define JIT_ARM_EXTENDED 0
+#endif
+
+#ifndef JIT_ARM_REALTIME 
+# define JIT_ARM_REALTIME 0
+#endif
+
+#ifndef JIT_ARM_VFP
+# define JIT_ARM_VFP 0
+#endif
+
+/* For now, thumb doesn't work with software float: */
+#if JIT_ARM_THUMB && !JIT_ARM_VFP
+# undef JIT_ARM_THUMB
+# define JIT_ARM_THUMB 0
+#endif
+
+# define jit_thumb_p() JIT_ARM_THUMB
+# define jit_neon_p()  JIT_ARM_NEON
+# define jit_hardfp_p() JIT_ARM_VFP
+# define jit_swf_p()    !JIT_ARM_VFP
+
+#define jit_armv5_p()   (JIT_ARM_VERSION >= 5)
+#define jit_armv5e_p()  ((JIT_ARM_VERSION > 5) || JIT_ARM_EXTENDED)
+#define jit_armv6_p()   (JIT_ARM_VERSION >= 6)
+#define jit_armv6t_p()  ((JIT_ARM_VERSION >= 6) && jit_thumb_p())
+#define jit_armv7r_p()	((JIT_ARM_VERSION >= 7) && JIT_ARM_REALTIME)
+
+
 typedef union _jit_thumb_t {
     int		i;
     short	s[2];
@@ -520,7 +590,7 @@ encode_vfp_double(int mov, int inv, unsigned lo, unsigned hi)
 {
     int		code, mode, imm, mask;
 
-    if (!jit_advsimd_p()) return -1;
+    if (!jit_neon_p()) return -1;
 
     if (hi != lo) {
 	if (mov && !inv) {

src/racket/src/lightning/arm/core-common.h

@@ -40,8 +40,8 @@
 #define	jit_get_label()			jit_get_ip()
 #define	jit_forward()			jit_get_ip()
 
-#define jit_adjust_ip(x) ((jit_insn *)(((char *)(x)) + jit_cpu.thumb))
+#define jit_adjust_ip(x) ((jit_insn *)(((char *)(x)) + (jit_thumb_p() ? 1 : 0)))
-#define jit_unadjust_ip(x) ((jit_insn *)(((char *)(x)) - jit_cpu.thumb))
+#define jit_unadjust_ip(x) ((jit_insn *)(((char *)(x)) - (jit_thumb_p() ? 1 : 0)))
 
 #define	jit_field(struc, f)		( ((long) (&((struc *) 8)->f) ) - 8)
 #define	jit_ptr_field(struc_p, f)	( ((long) (&((struc_p) 8)->f) ) - 8)

src/racket/src/lightning/arm/core.h

@@ -52,12 +52,6 @@ jit_v_order[JIT_V_NUM] = {
 #define JIT_V2				_R6
 
 #define jit_no_set_flags()		jit_flags.no_set_flags
-#define jit_armv5_p()			(jit_cpu.version >= 5)
-#define jit_armv5e_p()			(jit_cpu.version >= 5 && jit_cpu.extend)
-#define jit_armv7r_p()			0
-#define jit_armv6t_p()			((jit_cpu.version >= 6) && (jit_cpu.thumb))
-#define jit_swf_p()			(jit_cpu.vfp == 0)
-#define jit_hardfp_p()			jit_cpu.abi
 
 extern int	__aeabi_idivmod(int, int);
 extern unsigned	__aeabi_uidivmod(unsigned, unsigned);

src/racket/src/lightning/arm/funcs.h

@@ -67,6 +67,11 @@ jit_flush_code(void *start, void *end)
 __jit_constructor __jit_inline void
 jit_get_cpu(void)
 {
+#ifdef JIT_ARM_DYNAMIC_CPU
+  /* Dynamic tests may not be reliable ("/proc/cpuinfo" seems to give bad info
+     on Raspbian as of April 2013), and a static configuration has the advatange
+     of generating a more compact JIT. Some variant of this code may make sense
+     in the future, though. */
   static int	 initialized;
   
   if (initialized)
@@ -74,7 +79,7 @@ jit_get_cpu(void)
   
   initialized = 1;
   
-#if defined(__linux__)
+# if defined(__linux__)
   {
     FILE	*fp;
     char	*ptr;
@@ -110,18 +115,18 @@ jit_get_cpu(void)
     }
     fclose(fp);
   }
-#endif
+# endif
-#if defined(__ARM_PCS_VFP)
+# if defined(__ARM_PCS_VFP)
     if (!jit_cpu.vfp)
 	jit_cpu.vfp = 3;
     if (!jit_cpu.version)
 	jit_cpu.version = 7;
     jit_cpu.abi = 1;
-#endif
+# endif
-#ifdef __VFP_FP__
+# ifdef __VFP_FP__
     if (!jit_cpu.vfp)
 	jit_cpu.vfp = 1;
-#endif
+# endif
     /* armv6t2 todo (software float and thumb2) */
     if (!jit_cpu.vfp && jit_cpu.thumb)
 	jit_cpu.thumb = 0;
@@ -131,6 +136,7 @@ jit_get_cpu(void)
        whether or not a VFP ABI is in use (since we avoid passing
        floating-point arguments or receiving floating-point results in
        that mode). */
+#endif
 }
 
 #endif /* __lightning_funcs_h */