src/lj_vmmath.c

   1 /*
   2 ** Math helper functions for assembler VM.
   3 ** Copyright (C) 2005-2023 Mike Pall. See Copyright Notice in luajit.h
   4 */
   5
   6 #define lj_vmmath_c
   7 #define LUA_CORE
   8
   9 #include <errno.h>
  10 #include <math.h>
  11
  12 #include "lj_obj.h"
  13 #include "lj_ir.h"
  14 #include "lj_vm.h"
  15
  16 /* -- Wrapper functions --------------------------------------------------- */
  17
  18 #if LJ_TARGET_X86 && __ELF__ && __PIC__
  19 /* Wrapper functions to deal with the ELF/x86 PIC disaster. */
  20 LJ_FUNCA double lj_wrap_log(double x) { return log(x); }
  21 LJ_FUNCA double lj_wrap_log10(double x) { return log10(x); }
  22 LJ_FUNCA double lj_wrap_exp(double x) { return exp(x); }
  23 LJ_FUNCA double lj_wrap_sin(double x) { return sin(x); }
  24 LJ_FUNCA double lj_wrap_cos(double x) { return cos(x); }
  25 LJ_FUNCA double lj_wrap_tan(double x) { return tan(x); }
  26 LJ_FUNCA double lj_wrap_asin(double x) { return asin(x); }
  27 LJ_FUNCA double lj_wrap_acos(double x) { return acos(x); }
  28 LJ_FUNCA double lj_wrap_atan(double x) { return atan(x); }
  29 LJ_FUNCA double lj_wrap_sinh(double x) { return sinh(x); }
  30 LJ_FUNCA double lj_wrap_cosh(double x) { return cosh(x); }
  31 LJ_FUNCA double lj_wrap_tanh(double x) { return tanh(x); }
  32 LJ_FUNCA double lj_wrap_atan2(double x, double y) { return atan2(x, y); }
  33 LJ_FUNCA double lj_wrap_pow(double x, double y) { return pow(x, y); }
  34 LJ_FUNCA double lj_wrap_fmod(double x, double y) { return fmod(x, y); }
  35 #endif
  36
  37 /* -- Helper functions ---------------------------------------------------- */
  38
  39 /* Required to prevent the C compiler from applying FMA optimizations.
  40 **
  41 ** Yes, there's -ffp-contract and the FP_CONTRACT pragma ... in theory.
  42 ** But the current state of C compilers is a mess in this regard.
  43 ** Also, this function is not performance sensitive at all.
  44 */
  45 LJ_NOINLINE static double lj_vm_floormul(double x, double y)
  46 {
  47   return lj_vm_floor(x / y) * y;
  48 }
  49
  50 double lj_vm_foldarith(double x, double y, int op)
  51 {
  52   switch (op) {
  53   case IR_ADD - IR_ADD: return x+y; break;
  54   case IR_SUB - IR_ADD: return x-y; break;
  55   case IR_MUL - IR_ADD: return x*y; break;
  56   case IR_DIV - IR_ADD: return x/y; break;
  57   case IR_MOD - IR_ADD: return x-lj_vm_floormul(x, y); break;
  58   case IR_POW - IR_ADD: return pow(x, y); break;
  59   case IR_NEG - IR_ADD: return -x; break;
  60   case IR_ABS - IR_ADD: return fabs(x); break;
  61 #if LJ_HASJIT
  62   case IR_LDEXP - IR_ADD: return ldexp(x, (int)y); break;
  63   case IR_MIN - IR_ADD: return x < y ? x : y; break;
  64   case IR_MAX - IR_ADD: return x > y ? x : y; break;
  65 #endif
  66   default: return x;
  67   }
  68 }
  69
  70 /* -- Helper functions for generated machine code ------------------------- */
  71
  72 #if (LJ_HASJIT && !(LJ_TARGET_ARM || LJ_TARGET_ARM64 || LJ_TARGET_PPC)) || LJ_TARGET_MIPS
  73 int32_t LJ_FASTCALL lj_vm_modi(int32_t a, int32_t b)
  74 {
  75   uint32_t y, ua, ub;
  76   /* This must be checked before using this function. */
  77   lj_assertX(b != 0, "modulo with zero divisor");
  78   ua = a < 0 ? ~(uint32_t)a+1u : (uint32_t)a;
  79   ub = b < 0 ? ~(uint32_t)b+1u : (uint32_t)b;
  80   y = ua % ub;
  81   if (y != 0 && (a^b) < 0) y = y - ub;
  82   if (((int32_t)y^b) < 0) y = ~y+1u;
  83   return (int32_t)y;
  84 }
  85 #endif
  86
  87 #if LJ_HASJIT
  88
  89 #ifdef LUAJIT_NO_LOG2
  90 double lj_vm_log2(double a)
  91 {
  92   return log(a) * 1.4426950408889634074;
  93 }
  94 #endif
  95
  96 /* Computes fpm(x) for extended math functions. */
  97 double lj_vm_foldfpm(double x, int fpm)
  98 {
  99   switch (fpm) {
 100   case IRFPM_FLOOR: return lj_vm_floor(x);
 101   case IRFPM_CEIL: return lj_vm_ceil(x);
 102   case IRFPM_TRUNC: return lj_vm_trunc(x);
 103   case IRFPM_SQRT: return sqrt(x);
 104   case IRFPM_LOG: return log(x);
 105   case IRFPM_LOG2: return lj_vm_log2(x);
 106   default: lj_assertX(0, "bad fpm %d", fpm);
 107   }
 108   return 0;
 109 }
 110
 111 #if LJ_HASFFI
 112 int lj_vm_errno(void)
 113 {
 114   return errno;
 115 }
 116 #endif
 117
 118 #endif