diff options
Diffstat (limited to 'sysdeps/i386/fpu/e_powl.S')
| -rw-r--r-- | sysdeps/i386/fpu/e_powl.S | 56 |
1 files changed, 48 insertions, 8 deletions
diff --git a/sysdeps/i386/fpu/e_powl.S b/sysdeps/i386/fpu/e_powl.S index c0aa194c62..0e7c05bb82 100644 --- a/sysdeps/i386/fpu/e_powl.S +++ b/sysdeps/i386/fpu/e_powl.S @@ -117,7 +117,7 @@ ENTRY(__ieee754_powl) fucomp %st(1) // y : x fnstsw sahf - jne 2f + jne 3f /* OK, we have an integer value for y. */ popl %eax @@ -160,7 +160,14 @@ ENTRY(__ieee754_powl) cfi_adjust_cfa_offset (8) .align ALIGNARG(4) -2: /* y is a real number. */ +2: // y is a large integer (absolute value at least 1L<<63), but + // may be odd unless at least 1L<<64. So it may be necessary + // to adjust the sign of a negative result afterwards. + fxch // x : y + fabs // |x| : y + fxch // y : |x| + .align ALIGNARG(4) +3: /* y is a real number. */ fxch // x : y fldl MO(one) // 1.0 : x : y fldl MO(limit) // 0.29 : 1.0 : x : y @@ -190,18 +197,51 @@ ENTRY(__ieee754_powl) f2xm1 // 2^fract(y*log2(x))-1 : int(y*log2(x)) faddl MO(one) // 2^fract(y*log2(x)) : int(y*log2(x)) fscale // 2^fract(y*log2(x))*2^int(y*log2(x)) : int(y*log2(x)) - addl $8, %esp - cfi_adjust_cfa_offset (-8) fstp %st(1) // 2^fract(y*log2(x))*2^int(y*log2(x)) - ret + jmp 29f - cfi_adjust_cfa_offset (8) 28: fstp %st(1) // y*log2(x) fldl MO(one) // 1 : y*log2(x) fscale // 2^(y*log2(x)) : y*log2(x) - addl $8, %esp - cfi_adjust_cfa_offset (-8) fstp %st(1) // 2^(y*log2(x)) +29: testb $2, %dh + jz 292f + // x is negative. If y is an odd integer, negate the result. + fldt 24(%esp) // y : abs(result) + fld %st // y : y : abs(result) + fabs // |y| : y : abs(result) + fcompl MO(p64) // y : abs(result) + fnstsw + sahf + jnc 291f + fldl MO(p63) // p63 : y : abs(result) + fxch // y : p63 : abs(result) + fprem // y%p63 : p63 : abs(result) + fstp %st(1) // y%p63 : abs(result) + + // We must find out whether y is an odd integer. + fld %st // y : y : abs(result) + fistpll (%esp) // y : abs(result) + fildll (%esp) // int(y) : y : abs(result) + fucompp // abs(result) + fnstsw + sahf + jne 292f + + // OK, the value is an integer, but is it odd? + popl %eax + cfi_adjust_cfa_offset (-4) + popl %edx + cfi_adjust_cfa_offset (-4) + andb $1, %al + jz 290f // jump if not odd + // It's an odd integer. + fchs +290: ret + cfi_adjust_cfa_offset (8) +291: fstp %st(0) // abs(result) +292: addl $8, %esp + cfi_adjust_cfa_offset (-8) ret // pow(x,±0) = 1 |