[compiler-rt] Support FreeBSD standalone (boot) environment

[jrtc27]

Summary

FreeBSD uses -Ddouble=jagged-little-pill -Dfloat=floaty-mcfloatface to
poison uses of floating point in its standalone environment. It also
deprecates machine/limits.h in favour of sys/limits.h and does not even
provide the former on newer architectures.

This is a cleaner reimplementation of equivalent patches in FreeBSD's
vendored copy of compiler-rt.

[dim]

LGTM.

compiler-rt/lib/builtins/int_types.h

170

To avoid this repetition, maybe we should conditionally define something like CRT_HAS_FLOATING_POINT at the top of the file (for now under #if !(defined(__FreeBSD__) && defined(_STANDALONE)), and check #if CRT_HAS_FLOATING_POINT here and in the previous instance?

[jrtc27]

compiler-rt/lib/builtins/int_types.h

170

I thought about it but it was only two uses and didn't want to have to come up with a sensible name. But yes, that's probably nicer, will update.

[jrtc27]

Introduce CRT_HAS_FLOATING_POINT macro to avoid code duplication

compiler-rt/lib/builtins/int_lib.h

#define COMPILER_RT_ALIAS(name, aliasname) \
   __asm__(SYMBOL_NAME(aliasname) " = " SYMBOL_NAME(name)); \
   COMPILER_RT_ABI __typeof(name) aliasname;
 #elif defined(_WIN32)
 #define COMPILER_RT_ALIAS(name, aliasname)
 #else
 #error Unsupported target
 #endif
 
-#if defined(__NetBSD__) && (defined(_KERNEL) || defined(_STANDALONE))
+#if (defined(__FreeBSD__) || defined(__NetBSD__)) &&                           \
+    (defined(_KERNEL) || defined(_STANDALONE))
 //
 // Kernel and boot environment can't use normal headers,
 // so use the equivalent system headers.
+// NB: FreeBSD (and OpenBSD) deprecate machine/limits.h in
+// favour of sys/limits.h, so prefer the former, but fall
+// back on the latter if not available since NetBSD only has
+// the latter.
 //
+#if defined(__has_include) && __has_include(<sys/limits.h>)
+#include <sys/limits.h>
+#else
 #include <machine/limits.h>
+#endif
 #include <sys/stdint.h>
 #include <sys/types.h>
 #else
 // Include the standard compiler builtin headers we use functionality from.
 #include <float.h>
 #include <limits.h>
 #include <stdbool.h>
 #include <stdint.h>

compiler-rt/lib/builtins/int_types.h

static __inline tu_int make_tu(du_int h, du_int l) {
   utwords r;
   r.s.high = h;
   r.s.low = l;
   return r.all;
 }
 
 #endif // CRT_HAS_128BIT
 
+// FreeBSD's boot environment does not support using floating-point and poisons
+// the float and double keywords.
+#if defined(__FreeBSD__) && defined(_STANDALONE)
+#define CRT_HAS_FLOATING_POINT 0
+#else
+#define CRT_HAS_FLOATING_POINT 1
+#endif
+
+#if CRT_HAS_FLOATING_POINT
 typedef union {
   su_int u;
   float f;
 } float_bits;
 
 typedef union {
   udwords u;
   double f;
 } double_bits;
+#endif
 
 typedef struct {
 #if _YUGA_LITTLE_ENDIAN
   udwords low;
   udwords high;
 #else
   udwords high;
   udwords low;
#if (defined(__i386__) || defined(__x86_64__)) &&                              \
     !(defined(_MSC_VER) || defined(__ANDROID__))
 #define HAS_80_BIT_LONG_DOUBLE 1
 #elif defined(__m68k__) || defined(__ia64__)
 #define HAS_80_BIT_LONG_DOUBLE 1
 #else
 #define HAS_80_BIT_LONG_DOUBLE 0
 #endif
 
+#if CRT_HAS_FLOATING_POINT
 typedef union {
   uqwords u;
   long double f;
 } long_double_bits;
 
 #if __STDC_VERSION__ >= 199901L
 typedef float _Complex Fcomplex;
 typedef double _Complex Dcomplex;
 typedef long double _Complex Lcomplex;
 

 
 typedef struct {
   long double real, imaginary;
 } Lcomplex;
 
 #define COMPLEX_REAL(x) (x).real
 #define COMPLEX_IMAGINARY(x) (x).imaginary
 #endif
+#endif
 #endif // INT_TYPES_H