diff options
Diffstat (limited to 'gcc/fold-const.c')
| -rw-r--r-- | gcc/fold-const.c | 229 |
1 files changed, 229 insertions, 0 deletions
diff --git a/gcc/fold-const.c b/gcc/fold-const.c index c05c331daca..0937d74af0c 100644 --- a/gcc/fold-const.c +++ b/gcc/fold-const.c @@ -964,6 +964,235 @@ fail: *r = y.d; return 1; } + + +/* Convert C9X hexadecimal floating point string constant S. Return + real value type in mode MODE. This function uses the host computer's + fp arithmetic when there is no REAL_ARITHMETIC. */ + +REAL_VALUE_TYPE +real_hex_to_f (s, mode) + char *s; + enum machine_mode mode; +{ + REAL_VALUE_TYPE ip; + char *p = s; + unsigned HOST_WIDE_INT low, high; + int frexpon, expon, shcount, nrmcount, k; + int sign, expsign, decpt, isfloat, isldouble, gotp, lost; + char c; + + isldouble = 0; + isfloat = 0; + frexpon = 0; + expon = 0; + expsign = 1; + ip = 0.0; + + while (*p == ' ' || *p == '\t') + ++p; + + /* Sign, if any, comes first. */ + sign = 1; + if (*p == '-') + { + sign = -1; + ++p; + } + + /* The string is supposed to start with 0x or 0X . */ + if (*p == '0') + { + ++p; + if (*p == 'x' || *p == 'X') + ++p; + else + abort (); + } + else + abort (); + + while (*p == '0') + ++p; + + high = 0; + low = 0; + lost = 0; /* Nonzero low order bits shifted out and discarded. */ + frexpon = 0; /* Bits after the decimal point. */ + expon = 0; /* Value of exponent. */ + decpt = 0; /* How many decimal points. */ + gotp = 0; /* How many P's. */ + shcount = 0; + while ((c = *p) != '\0') + { + if ((c >= '0' && c <= '9') || (c >= 'A' && c <= 'F') + || (c >= 'a' && c <= 'f')) + { + k = c & 0x7f; + if (k >= 'a') + k = k - 'a' + 10; + else if (k >= 'A') + k = k - 'A' + 10; + else + k = k - '0'; + + if ((high & 0xf0000000) == 0) + { + high = (high << 4) + ((low >> 28) & 15); + low = (low << 4) + k; + shcount += 4; + if (decpt) + frexpon += 4; + } + else + { + /* Record nonzero lost bits. */ + lost |= k; + if (!decpt) + frexpon -= 4; + } + ++p; + } + else if ( c == '.') + { + ++decpt; + ++p; + } + else if (c == 'p' || c == 'P') + { + ++gotp; + ++p; + /* Sign of exponent. */ + if (*p == '-') + { + expsign = -1; + ++p; + } + /* Value of exponent. + The exponent field is a decimal integer. */ + while (isdigit(*p)) + { + k = (*p++ & 0x7f) - '0'; + expon = 10 * expon + k; + } + expon *= expsign; + /* F suffix is ambiguous in the significand part + so it must appear after the decimal exponent field. */ + if (*p == 'f' || *p == 'F') + { + isfloat = 1; + ++p; + break; + } + } + else if (c == 'l' || c == 'L') + { + isldouble = 1; + ++p; + break; + } + else + break; + } + /* Abort if last character read was not legitimate. */ + c = *p; + if ((c != '\0' && c != ' ' && c != '\n' && c != '\r') || (decpt > 1)) + abort (); + /* There must be either one decimal point or one p. */ + if (decpt == 0 && gotp == 0) + abort (); + shcount -= 4; + if ((high == 0) && (low == 0)) + { + return dconst0; + } + + /* Normalize. */ + nrmcount = 0; + if (high == 0) + { + high = low; + low = 0; + nrmcount += 32; + } + /* Leave a high guard bit for carry-out. */ + if ((high & 0x80000000) != 0) + { + lost |= low & 1; + low = (low >> 1) | (high << 31); + high = high >> 1; + nrmcount -= 1; + } + if ((high & 0xffff8000) == 0) + { + high = (high << 16) + ((low >> 16) & 0xffff); + low = low << 16; + nrmcount += 16; + } + while ((high & 0xc0000000) == 0) + { + high = (high << 1) + ((low >> 31) & 1); + low = low << 1; + nrmcount += 1; + } + if (isfloat || GET_MODE_SIZE(mode) == UNITS_PER_WORD) + { + /* Keep 24 bits precision, bits 0x7fffff80. + Rounding bit is 0x40. */ + lost = lost | low | (high & 0x3f); + low = 0; + if (high & 0x40) + { + if ((high & 0x80) || lost) + high += 0x40; + } + high &= 0xffffff80; + } + else + { + /* We need real.c to do long double formats, so here default + to double precision. */ +#if HOST_FLOAT_FORMAT == IEEE_FLOAT_FORMAT + /* IEEE double. + Keep 53 bits precision, bits 0x7fffffff fffffc00. + Rounding bit is low word 0x200. */ + lost = lost | (low & 0x1ff); + if (low & 0x200) + { + if ((low & 0x400) || lost) + { + low = (low + 0x200) & 0xfffffc00; + if (low == 0) + high += 1; + } + } + low &= 0xfffffc00; +#else + /* Assume it's a VAX with 56-bit significand, + bits 0x7fffffff ffffff80. */ + lost = lost | (low & 0x7f); + if (low & 0x40) + { + if ((low & 0x80) || lost) + { + low = (low + 0x40) & 0xffffff80; + if (low == 0) + high += 1; + } + } + low &= 0xffffff80; +#endif + } + ip = (double) high; + ip = REAL_VALUE_LDEXP (ip, 32) + (double) low; + /* Apply shifts and exponent value as power of 2. */ + ip = REAL_VALUE_LDEXP (ip, expon - (nrmcount + frexpon)); + + if (sign < 0) + ip = -ip; + return ip; +} + #endif /* no REAL_ARITHMETIC */ /* Split a tree IN into a constant and a variable part |