diff options
Diffstat (limited to 'sysdeps/sparc/sparc64/fpu/multiarch/s_floor-vis3.S')
| -rw-r--r-- | sysdeps/sparc/sparc64/fpu/multiarch/s_floor-vis3.S | 38 |
1 files changed, 11 insertions, 27 deletions
diff --git a/sysdeps/sparc/sparc64/fpu/multiarch/s_floor-vis3.S b/sysdeps/sparc/sparc64/fpu/multiarch/s_floor-vis3.S index 169d206549..c2ffe9f411 100644 --- a/sysdeps/sparc/sparc64/fpu/multiarch/s_floor-vis3.S +++ b/sysdeps/sparc/sparc64/fpu/multiarch/s_floor-vis3.S @@ -19,57 +19,41 @@ #include <sysdep.h> - /* Since changing the rounding mode is extremely expensive, we - try to round up using a method that is rounding mode - agnostic. + /* 'siam' (Set Interval Arithmetic Mode) is used to quickly override + the rounding mode during this routine. We add then subtract (or subtract than add if the initial value was negative) 2**23 to the value, then subtract it back out. - This will clear out the fractional portion of the value. - One of two things will happen for non-whole initial values. - Either the rounding mode will round it up, or it will be - rounded down. If the value started out whole, it will be - equal after the addition and subtraction. This means we - can accurately detect with one test whether we need to add - another 1.0 to round it up properly. + This will clear out the fractional portion of the value and, + with suitable 'siam' initiated rouding mode settings, round + the final result in the proper direction. - VIS instructions are used to facilitate the formation of - easier constants, and the propagation of the sign bit. */ + We also use VIS3 moves to avoid using the stack to transfer + values between float and integer registers. */ #define TWO_FIFTYTWO 0x43300000 /* 2**52 */ -#define ONE_DOT_ZERO 0x3ff00000 /* 1.0 */ #define ZERO %f10 /* 0.0 */ #define SIGN_BIT %f12 /* -0.0 */ ENTRY (__floor_vis3) sethi %hi(TWO_FIFTYTWO), %o2 - sethi %hi(ONE_DOT_ZERO), %o3 fzero ZERO - sllx %o2, 32, %o2 fnegd ZERO, SIGN_BIT - - sllx %o3, 32, %o3 movxtod %o2, %f16 fabsd %f0, %f14 - fcmpd %fcc3, %f14, %f16 - fmovduge %fcc3, ZERO, %f16 fand %f0, SIGN_BIT, SIGN_BIT - for %f16, SIGN_BIT, %f16 + siam (1 << 2) | 3 faddd %f0, %f16, %f18 + siam (1 << 2) | 0 fsubd %f18, %f16, %f18 - fcmpd %fcc2, %f18, %f0 - movxtod %o3, %f20 - - fmovdule %fcc2, ZERO, %f20 - fsubd %f18, %f20, %f0 - fabsd %f0, %f0 + siam (0 << 2) retl - for %f0, SIGN_BIT, %f0 + for %f18, SIGN_BIT, %f0 END (__floor_vis3) |