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go/src/math/dim_amd64.s
Charlie Dorian ec92af650c math: Dim, Max, Min - allow more bit patterns for NaN
Fixes #9919

Change-Id: Ib443c762f727d4986ca7f8a404362f92b0e91aff
Reviewed-on: https://go-review.googlesource.com/5553
Reviewed-by: Minux Ma <minux@golang.org>
2015-02-23 23:07:01 +00:00

137 lines
2.6 KiB
ArmAsm

// Copyright 2010 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
#include "textflag.h"
#define PosInf 0x7FF0000000000000
#define NaN 0x7FF8000000000001
#define NegInf 0xFFF0000000000000
// func Dim(x, y float64) float64
TEXT ·Dim(SB),NOSPLIT,$0
// (+Inf, +Inf) special case
MOVQ x+0(FP), BX
MOVQ y+8(FP), CX
MOVQ $PosInf, AX
CMPQ AX, BX
JNE dim2
CMPQ AX, CX
JEQ bothInf
dim2: // (-Inf, -Inf) special case
MOVQ $NegInf, AX
CMPQ AX, BX
JNE dim3
CMPQ AX, CX
JEQ bothInf
dim3: // (NaN, x) or (x, NaN)
MOVQ $~(1<<63), DX
MOVQ $PosInf, AX
ANDQ DX, BX // x = |x|
CMPQ AX, BX
JLT isDimNaN
ANDQ DX, CX // y = |y|
CMPQ AX, CX
JLT isDimNaN
MOVSD x+0(FP), X0
SUBSD y+8(FP), X0
MOVSD $(0.0), X1
MAXSD X1, X0
MOVSD X0, ret+16(FP)
RET
bothInf: // Dim(-Inf, -Inf) or Dim(+Inf, +Inf)
isDimNaN:
MOVQ $NaN, AX
MOVQ AX, ret+16(FP)
RET
// func ·Max(x, y float64) float64
TEXT ·Max(SB),NOSPLIT,$0
// +Inf special cases
MOVQ $PosInf, AX
MOVQ x+0(FP), R8
CMPQ AX, R8
JEQ isPosInf
MOVQ y+8(FP), R9
CMPQ AX, R9
JEQ isPosInf
// NaN special cases
MOVQ $~(1<<63), DX // bit mask
MOVQ $PosInf, AX
MOVQ R8, BX
ANDQ DX, BX // x = |x|
CMPQ AX, BX
JLT isMaxNaN
MOVQ R9, CX
ANDQ DX, CX // y = |y|
CMPQ AX, CX
JLT isMaxNaN
// ±0 special cases
ORQ CX, BX
JEQ isMaxZero
MOVQ R8, X0
MOVQ R9, X1
MAXSD X1, X0
MOVSD X0, ret+16(FP)
RET
isMaxNaN: // return NaN
MOVQ $NaN, AX
isPosInf: // return +Inf
MOVQ AX, ret+16(FP)
RET
isMaxZero:
MOVQ $(1<<63), AX // -0.0
CMPQ AX, R8
JEQ +3(PC)
MOVQ R8, ret+16(FP) // return 0
RET
MOVQ R9, ret+16(FP) // return other 0
RET
// func Min(x, y float64) float64
TEXT ·Min(SB),NOSPLIT,$0
// -Inf special cases
MOVQ $NegInf, AX
MOVQ x+0(FP), R8
CMPQ AX, R8
JEQ isNegInf
MOVQ y+8(FP), R9
CMPQ AX, R9
JEQ isNegInf
// NaN special cases
MOVQ $~(1<<63), DX
MOVQ $PosInf, AX
MOVQ R8, BX
ANDQ DX, BX // x = |x|
CMPQ AX, BX
JLT isMinNaN
MOVQ R9, CX
ANDQ DX, CX // y = |y|
CMPQ AX, CX
JLT isMinNaN
// ±0 special cases
ORQ CX, BX
JEQ isMinZero
MOVQ R8, X0
MOVQ R9, X1
MINSD X1, X0
MOVSD X0, ret+16(FP)
RET
isMinNaN: // return NaN
MOVQ $NaN, AX
isNegInf: // return -Inf
MOVQ AX, ret+16(FP)
RET
isMinZero:
MOVQ $(1<<63), AX // -0.0
CMPQ AX, R8
JEQ +3(PC)
MOVQ R9, ret+16(FP) // return other 0
RET
MOVQ R8, ret+16(FP) // return -0
RET