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PPC: Add heavily optimized floor/ceil/trunc functions.

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Mike Pall 2010-09-08 00:09:36 +02:00
parent db735e0519
commit e9e7df5bfe
1 changed files with 69 additions and 3 deletions
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72
src/buildvm_ppc.dasc
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@ -887,10 +887,75 @@ static void build_subroutines(BuildCtx *ctx)
| |
|// FP value rounding. Called by math.floor/math.ceil fast functions |// FP value rounding. Called by math.floor/math.ceil fast functions
|// and from JIT code. |// and from JIT code.
| |//
|// This can be inlined if the CPU has the frin/friz/frip/frim instructions.
|// The alternative hard-float approaches have a deep dependency chain.
|// The resulting latency is at least 3x-7x the double-precision FP latency
|// (e500v2: 6cy, e600: 5cy, Cell: 10cy) or around 20-70 cycles.
|//
|// The soft-float approach is tedious, but much faster (e500v2: ~11cy/~6cy).
|// However it relies on a fast way to transfer the FP value to GPRs
|// (e500v2: 0cy for lo-word, 1cy for hi-word).
|//
|.macro vm_round, name, mode |.macro vm_round, name, mode
|->name: | // Used temporaries: TMP0, TMP1, TMP2, TMP3.
| NYI |->name: // Input: CARG2, output: CRET2
| evmergehi CARG1, CARG2, CARG2
|->name.._hilo:
| // Input: CARG1 (hi), CARG2 (hi, lo), output: CRET2
| rlwinm TMP2, CARG1, 12, 21, 31
| addic. TMP2, TMP2, -1023 // exp = exponent(x) - 1023
| li TMP1, -1
| cmplwi cr1, TMP2, 51 // 0 <= exp < 51?
| subfic TMP0, TMP2, 52
| bgt cr1, >1
| lus TMP3, 0xfff0
| slw TMP0, TMP1, TMP0 // lomask = -1 << (52-exp)
| sraw TMP1, TMP3, TMP2 // himask = (int32_t)0xfff00000 >> exp
|.if mode == 2 // trunc(x):
| evmergelo TMP0, TMP1, TMP0
| evand CRET2, CARG2, TMP0 // hi &= himask, lo &= lomask
|.else
| andc TMP2, CARG2, TMP0
| andc TMP3, CARG1, TMP1
| or TMP2, TMP2, TMP3 // ztest = (hi&~himask) | (lo&~lomask)
| srawi TMP3, CARG1, 31 // signmask = (int32_t)hi >> 31
|.if mode == 0 // floor(x):
| and. TMP2, TMP2, TMP3 // iszero = ((ztest & signmask) == 0)
|.else // ceil(x):
| andc. TMP2, TMP2, TMP3 // iszero = ((ztest & ~signmask) == 0)
|.endif
| and CARG2, CARG2, TMP0 // lo &= lomask
| and CARG1, CARG1, TMP1 // hi &= himask
| subc TMP0, CARG2, TMP0
| iseleq TMP0, CARG2, TMP0 // lo = iszero ? lo : lo-lomask
| sube TMP1, CARG1, TMP1
| iseleq TMP1, CARG1, TMP1 // hi = iszero ? hi : hi-himask+carry
| evmergelo CRET2, TMP1, TMP0
|.endif
| blr
|1:
| bgtlr // Already done if >=2^52, +-inf or nan.
|.if mode == 2 // trunc(x):
| rlwinm TMP1, CARG1, 0, 0, 0 // hi = sign(x)
| li TMP0, 0
| evmergelo CRET2, TMP1, TMP0
|.else
| rlwinm TMP2, CARG1, 0, 1, 31
| srawi TMP0, CARG1, 31 // signmask = (int32_t)hi >> 31
| or TMP2, TMP2, CARG2 // ztest = abs(hi) | lo
| lus TMP1, 0x3ff0
|.if mode == 0 // floor(x):
| and. TMP2, TMP2, TMP0 // iszero = ((ztest & signmask) == 0)
|.else // ceil(x):
| andc. TMP2, TMP2, TMP0 // iszero = ((ztest & ~signmask) == 0)
|.endif
| li TMP0, 0
| iseleq TMP1, r0, TMP1
| rlwimi CARG1, TMP1, 0, 1, 31 // hi = sign(x) | (iszero ? 0.0 : 1.0)
| evmergelo CRET2, CARG1, TMP0
|.endif
| blr
|.endmacro |.endmacro
| |
| vm_round vm_floor, 0 | vm_round vm_floor, 0
@ -899,6 +964,7 @@ static void build_subroutines(BuildCtx *ctx)
| vm_round vm_trunc, 2 | vm_round vm_trunc, 2
#else #else
|->vm_trunc: |->vm_trunc:
|->vm_trunc_hilo:
#endif #endif
| |
|->vm_powi: |->vm_powi: