asmgen

package standard library
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 Go to latest Published: Jul 8, 2025 License: BSD-3-Clause Imports: 6 Imported by: 0

Documentation

Overview

Asmgen generates math/big assembly.

Usage: 

cd go/src/math/big
go test ./internal/asmgen -generate

Or: 

go generate math/big

Index

Constants

This section is empty.

Variables

View Source 
var Arch386 = &Arch{
	Name:      "386",
	WordBits:  32,
	WordBytes: 4,

	regs: []string{
		"BX", "SI", "DI", "BP",
		"CX", "DX", "AX",
	},
	op3:              x86Op3,
	hint:             x86Hint,
	memOK:            true,
	subCarryIsBorrow: true,
	maxColumns:       1,

	memIndex: _386MemIndex,

	mov:      "MOVL",
	adds:     "ADDL",
	adcs:     "ADCL",
	subs:     "SUBL",
	sbcs:     "SBBL",
	lsh:      "SHLL",
	lshd:     "SHLL",
	rsh:      "SHRL",
	rshd:     "SHRL",
	and:      "ANDL",
	or:       "ORL",
	xor:      "XORL",
	neg:      "NEGL",
	lea:      "LEAL",
	mulWideF: x86MulWide,

	addWords: "LEAL (%[2]s)(%[1]s*4), %[3]s",

	jmpZero:       "TESTL %[1]s, %[1]s; JZ %[2]s",
	jmpNonZero:    "TESTL %[1]s, %[1]s; JNZ %[2]s",
	loopBottom:    "SUBL $1, %[1]s; JNZ %[2]s",
	loopBottomNeg: "ADDL $1, %[1]s; JNZ %[2]s",
}
View Source 
var ArchAMD64 = &Arch{
	Name:      "amd64",
	WordBits:  64,
	WordBytes: 8,

	regs: []string{
		"BX", "SI", "DI",
		"R8", "R9", "R10", "R11", "R12", "R13", "R14", "R15",
		"AX", "DX", "CX",
	},
	op3:              x86Op3,
	hint:             x86Hint,
	memOK:            true,
	subCarryIsBorrow: true,

	options: map[Option]func(*Asm, string){
		OptionAltCarry: amd64JmpADX,
	},

	mov:      "MOVQ",
	adds:     "ADDQ",
	adcs:     "ADCQ",
	subs:     "SUBQ",
	sbcs:     "SBBQ",
	lsh:      "SHLQ",
	lshd:     "SHLQ",
	rsh:      "SHRQ",
	rshd:     "SHRQ",
	and:      "ANDQ",
	or:       "ORQ",
	xor:      "XORQ",
	neg:      "NEGQ",
	lea:      "LEAQ",
	addF:     amd64Add,
	mulWideF: x86MulWide,

	addWords: "LEAQ (%[2]s)(%[1]s*8), %[3]s",

	jmpZero:       "TESTQ %[1]s, %[1]s; JZ %[2]s",
	jmpNonZero:    "TESTQ %[1]s, %[1]s; JNZ %[2]s",
	loopBottom:    "SUBQ $1, %[1]s; JNZ %[2]s",
	loopBottomNeg: "ADDQ $1, %[1]s; JNZ %[2]s",
}
View Source 
var ArchARM = &Arch{
	Name:          "arm",
	WordBits:      32,
	WordBytes:     4,
	CarrySafeLoop: true,

	regs: []string{

		"R0", "R1", "R2", "R3", "R4", "R5", "R6", "R7", "R8", "R9", "R11", "R12",
	},
	regShift: true,

	mov:  "MOVW",
	add:  "ADD",
	adds: "ADD.S",
	adc:  "ADC",
	adcs: "ADC.S",
	sub:  "SUB",
	subs: "SUB.S",
	sbc:  "SBC",
	sbcs: "SBC.S",
	rsb:  "RSB",
	and:  "AND",
	or:   "ORR",
	xor:  "EOR",

	mulWideF: armMulWide,

	addWords: "ADD %s<<2, %s, %s",

	jmpZero:    "TEQ $0, %s; BEQ %s",
	jmpNonZero: "TEQ $0, %s; BNE %s",

	loadIncN:  armLoadIncN,
	loadDecN:  armLoadDecN,
	storeIncN: armStoreIncN,
	storeDecN: armStoreDecN,
}
View Source 
var ArchARM64 = &Arch{
	Name:          "arm64",
	WordBits:      64,
	WordBytes:     8,
	CarrySafeLoop: true,

	regs: []string{

		"R0", "R1", "R2", "R3", "R4", "R5", "R6", "R7", "R8", "R9",
		"R10", "R11", "R12", "R13", "R14", "R15", "R16", "R17", "R19",
		"R20", "R21", "R22", "R23", "R24", "R25", "R26",
	},
	reg0: "ZR",

	mov:   "MOVD",
	add:   "ADD",
	adds:  "ADDS",
	adc:   "ADC",
	adcs:  "ADCS",
	sub:   "SUB",
	subs:  "SUBS",
	sbc:   "SBC",
	sbcs:  "SBCS",
	mul:   "MUL",
	mulhi: "UMULH",
	lsh:   "LSL",
	rsh:   "LSR",
	and:   "AND",
	or:    "ORR",
	xor:   "EOR",

	addWords: "ADD %[1]s<<3, %[2]s, %[3]s",

	jmpZero:    "CBZ %s, %s",
	jmpNonZero: "CBNZ %s, %s",

	loadIncN:  arm64LoadIncN,
	loadDecN:  arm64LoadDecN,
	storeIncN: arm64StoreIncN,
	storeDecN: arm64StoreDecN,
}
View Source 
var ArchLoong64 = &Arch{
	Name:          "loong64",
	WordBits:      64,
	WordBytes:     8,
	CarrySafeLoop: true,

	regs: []string{

		"R4", "R5", "R6", "R7", "R8", "R9",
		"R10", "R11", "R12", "R13", "R14", "R15", "R16", "R17", "R18", "R19",
		"R20", "R21", "R23", "R24", "R25", "R26", "R27",
		"R31",
	},
	reg0:        "R0",
	regCarry:    "R28",
	regAltCarry: "R29",
	regTmp:      "R30",

	mov:   "MOVV",
	add:   "ADDVU",
	sub:   "SUBVU",
	sltu:  "SGTU",
	mul:   "MULV",
	mulhi: "MULHVU",
	lsh:   "SLLV",
	rsh:   "SRLV",
	and:   "AND",
	or:    "OR",
	xor:   "XOR",

	jmpZero:    "BEQ %s, %s",
	jmpNonZero: "BNE %s, %s",
}
View Source 
var ArchMIPS = &Arch{
	Name:          "mipsx",
	Build:         "mips || mipsle",
	WordBits:      32,
	WordBytes:     4,
	CarrySafeLoop: true,

	regs: []string{

		"R1", "R2", "R3", "R4", "R5", "R6", "R7", "R8", "R9",
		"R10", "R11", "R12", "R13", "R14", "R15", "R16", "R17", "R18", "R19",
		"R20", "R21", "R22", "R24", "R25",
	},
	reg0:        "R0",
	regTmp:      "R23",
	regCarry:    "R24",
	regAltCarry: "R25",

	mov:      "MOVW",
	add:      "ADDU",
	sltu:     "SGTU",
	sub:      "SUBU",
	mulWideF: mipsMulWide,
	lsh:      "SLL",
	rsh:      "SRL",
	and:      "AND",
	or:       "OR",
	xor:      "XOR",

	jmpZero:    "BEQ %s, %s",
	jmpNonZero: "BNE %s, %s",
}
View Source 
var ArchMIPS64x = &Arch{
	Name:          "mips64x",
	Build:         "mips64 || mips64le",
	WordBits:      64,
	WordBytes:     8,
	CarrySafeLoop: true,

	regs: []string{

		"R1", "R2", "R3", "R4", "R5", "R6", "R7", "R8", "R9",
		"R10", "R11", "R12", "R13", "R14", "R15", "R16", "R17", "R18", "R19",
		"R20", "R21", "R22", "R24", "R25",
	},
	reg0:        "R0",
	regTmp:      "R23",
	regCarry:    "R24",
	regAltCarry: "R25",

	mov:      "MOVV",
	add:      "ADDVU",
	sltu:     "SGTU",
	sub:      "SUBVU",
	mulWideF: mips64MulWide,
	lsh:      "SLLV",
	rsh:      "SRLV",
	and:      "AND",
	or:       "OR",
	xor:      "XOR",

	jmpZero:    "BEQ %s, %s",
	jmpNonZero: "BNE %s, %s",
}
View Source 
var ArchPPC64x = &Arch{
	Name:          "ppc64x",
	Build:         "ppc64 || ppc64le",
	WordBits:      64,
	WordBytes:     8,
	CarrySafeLoop: true,

	regs: []string{

		"R3", "R4", "R5", "R6", "R7", "R8", "R9",
		"R10", "R11", "R12", "R14", "R15", "R16", "R17", "R18", "R19",
		"R20", "R21", "R22", "R23", "R24", "R25", "R26", "R27", "R28", "R29",
	},
	reg0:   "R0",
	regTmp: "R31",

	mov:   "MOVD",
	add:   "ADD",
	adds:  "ADDC",
	adcs:  "ADDE",
	sub:   "SUB",
	subs:  "SUBC",
	sbcs:  "SUBE",
	mul:   "MULLD",
	mulhi: "MULHDU",
	lsh:   "SLD",
	rsh:   "SRD",
	and:   "ANDCC",
	or:    "OR",
	xor:   "XOR",

	jmpZero:    "CMP %[1]s, $0; BEQ %[2]s",
	jmpNonZero: "CMP %s, $0; BNE %s",

	loopTop:    "CMP %[1]s, $0; BEQ %[2]s; MOVD %[1]s, CTR",
	loopBottom: "BDNZ %[2]s",
}
View Source 
var ArchRISCV64 = &Arch{
	Name:          "riscv64",
	WordBits:      64,
	WordBytes:     8,
	CarrySafeLoop: true,

	regs: []string{

		"X5", "X6", "X7", "X8", "X9",
		"X10", "X11", "X12", "X13", "X14", "X15", "X16", "X17", "X18", "X19",
		"X20", "X21", "X22", "X23", "X24", "X25", "X26",
		"X30",
	},

	reg0:        "X0",
	regCarry:    "X28",
	regAltCarry: "X29",
	regTmp:      "X31",

	mov:   "MOV",
	add:   "ADD",
	sub:   "SUB",
	mul:   "MUL",
	mulhi: "MULHU",
	lsh:   "SLL",
	rsh:   "SRL",
	and:   "AND",
	or:    "OR",
	xor:   "XOR",
	sltu:  "SLTU",

	jmpZero:    "BEQZ %s, %s",
	jmpNonZero: "BNEZ %s, %s",
}
View Source 
var ArchS390X = &Arch{
	Name:          "s390x",
	WordBits:      64,
	WordBytes:     8,
	CarrySafeLoop: true,

	regs: []string{

		"R1", "R2", "R3", "R4", "R5", "R6", "R7", "R8", "R9",
		"R10", "R11", "R12",
	},
	reg0:       "R0",
	regTmp:     "R10",
	setup:      s390xSetup,
	maxColumns: 2,
	op3:        s390xOp3,
	hint:       s390xHint,

	mov:      "MOVD",
	adds:     "ADDC",
	adcs:     "ADDE",
	subs:     "SUBC",
	sbcs:     "SUBE",
	mulWideF: s390MulWide,
	lsh:      "SLD",
	rsh:      "SRD",
	and:      "AND",
	or:       "OR",
	xor:      "XOR",
	neg:      "NEG",
	lea:      "LAY",

	jmpZero:    "CMPBEQ %s, $0, %s",
	jmpNonZero: "CMPBNE %s, $0, %s",
}

Functions

This section is empty.

Types

type Arch 

type Arch struct {
	Name          string // name of architecture
	Build         string // build tag
	WordBits      int    // length of word in bits (32 or 64)
	WordBytes     int    // length of word in bytes (4 or 8)
	CarrySafeLoop bool   // whether loops preserve carry flag across iterations
	// contains filtered or unexported fields
}

An Arch defines how to generate assembly for a specific architecture.

func (*Arch) HasShiftWide 

func (a *Arch) HasShiftWide() bool

HasShiftWide reports whether the Arch has working LshWide/RshWide instructions. If not, calling them will panic.

type Asm 

type Asm struct {
	Arch *Arch // architecture
	// contains filtered or unexported fields
}

An Asm is an assembly file being written.

func NewAsm 

func NewAsm(arch *Arch) *Asm

NewAsm returns a new Asm preparing assembly for the given architecture to be written to file.

func (*Asm) Add 

func (a *Asm) Add(src1, src2, dst Reg, carry Carry)

Add emits dst = src1+src2, with the specified carry behavior.

func (*Asm) AddWords 

func (a *Asm) AddWords(src1 Reg, src2, dst RegPtr)

AddWords emits dst = src1*WordBytes + src2. It does not set or use the carry flag.

func (*Asm) AltCarry 

func (a *Asm) AltCarry() Reg

AltCarry returns the secondary carry register, or else the zero Reg.

func (*Asm) And 

func (a *Asm) And(src1, src2, dst Reg)

And emits dst = src1 & src2 It may modify the carry flag.

func (*Asm) Carry 

func (a *Asm) Carry() Reg

Carry returns the carry register, or else the zero Reg.

func (*Asm) ClearCarry 

func (a *Asm) ClearCarry(which Carry)

ClearCarry clears the carry flag. The ‘which’ parameter must be AddCarry or SubCarry to specify how the flag will be used. (On some systems, the sub carry's actual processor bit is inverted from its usual value.)

func (*Asm) Comment 

func (a *Asm) Comment(format string, args ...any)

Comment emits a line comment to the assembly output.

func (*Asm) ConvertCarry 

func (a *Asm) ConvertCarry(which Carry, dst Reg)

ConvertCarry converts the carry flag in dst from the internal format to a 0 or 1. The carry flag is left in an undefined state.

func (*Asm) EOL 

func (a *Asm) EOL(format string, args ...any)

EOL appends an end-of-line comment to the previous line.

func (*Asm) Enabled 

func (a *Asm) Enabled(option Option) bool

Enabled reports whether the optional CPU feature is considered to be enabled at this point in the assembly output.

func (*Asm) Fatalf 

func (a *Asm) Fatalf(format string, args ...any)

Fatalf reports a fatal error by panicking. Panicking is appropriate because there is a bug in the generator, and panicking will show the exact source lines leading to that bug.

func (*Asm) Free 

func (a *Asm) Free(r Reg)

Free frees a previously allocated register. If r is not a register (if it's an immediate or a memory reference), Free is a no-op.

func (*Asm) FreeAll 

func (a *Asm) FreeAll()

FreeAll frees all known registers.

func (*Asm) Func 

func (a *Asm) Func(decl string) *Func

Func starts a new function in the assembly output.

func (*Asm) HasRegShift 

func (a *Asm) HasRegShift() bool

HasRegShift reports whether the architecture can use shift expressions as operands.

func (*Asm) Imm 

func (a *Asm) Imm(x int) Reg

Imm returns a Reg representing an immediate (constant) value.

func (*Asm) IsZero 

func (a *Asm) IsZero(r Reg) bool

IsZero reports whether r is a zero immediate or the zero register.

func (*Asm) Jmp 

func (a *Asm) Jmp(label string)

Jmp jumps to the label.

func (*Asm) JmpEnable 

func (a *Asm) JmpEnable(option Option, label string) bool

JmpEnable emits a test for the optional CPU feature that jumps to label if the feature is present. If JmpEnable returns false, the feature is not available on this architecture and no code was emitted.

func (*Asm) JmpNonZero 

func (a *Asm) JmpNonZero(src Reg, label string)

JmpNonZero jumps to the label if src is non-zero. It may modify the carry flag unless a.Arch,CarrySafeLoop is true.

func (*Asm) JmpZero 

func (a *Asm) JmpZero(src Reg, label string)

JmpZero jumps to the label if src is zero. It may modify the carry flag unless a.Arch.CarrySafeLoop is true.

func (*Asm) Label 

func (a *Asm) Label(name string)

Label emits a label with the given name.

func (*Asm) Lsh 

func (a *Asm) Lsh(shift, src, dst Reg)

Lsh emits dst = src << shift. It may modify the carry flag.

func (*Asm) LshReg 

func (a *Asm) LshReg(shift, src Reg) Reg

LshReg returns a shift-expression operand src<<shift. If a.HasRegShift() == false, LshReg panics.

func (*Asm) LshWide 

func (a *Asm) LshWide(shift, adj, src, dst Reg)

LshWide emits dst = src << shift with low bits shifted from adj. It may modify the carry flag.

func (*Asm) Mov 

func (a *Asm) Mov(src, dst Reg)

Mov emits dst = src.

func (*Asm) MulWide 

func (a *Asm) MulWide(src1, src2, dstlo, dsthi Reg)

MulWide emits dstlo = src1 * src2 and dsthi = (src1 * src2) >> WordBits. The carry flag is left in an undefined state. If dstlo or dsthi is the zero Reg, then those outputs are discarded.

func (*Asm) Neg 

func (a *Asm) Neg(src, dst Reg)

Neg emits dst = -src. It may modify the carry flag.

func (*Asm) Or 

func (a *Asm) Or(src1, src2, dst Reg)

Or emits dst = src1 | src2 It may modify the carry flag.

func (*Asm) Printf 

func (a *Asm) Printf(format string, args ...any)

Printf emits to the assembly output.

func (*Asm) Reg 

func (a *Asm) Reg() Reg

Reg allocates a new register.

func (*Asm) RegHint 

func (a *Asm) RegHint(hint Hint) Reg

RegHint allocates a new register, with a hint as to its purpose.

func (*Asm) RegsUsed 

func (a *Asm) RegsUsed() RegsUsed

RegsUsed returns a snapshot of which registers are currently allocated, which can be passed to a future call to Asm.SetRegsUsed.

func (*Asm) RestoreCarry 

func (a *Asm) RestoreCarry(src Reg)

RestoreCarry restores the carry flag from src. src is left in an undefined state.

func (*Asm) Ret 

func (a *Asm) Ret()

Ret returns.

func (*Asm) Rsh 

func (a *Asm) Rsh(shift, src, dst Reg)

Rsh emits dst = src >> shift. It may modify the carry flag.

func (*Asm) RshReg 

func (a *Asm) RshReg(shift, src Reg) Reg

RshReg returns a shift-expression operand src>>shift. If a.HasRegShift() == false, RshReg panics.

func (*Asm) RshWide 

func (a *Asm) RshWide(shift, adj, src, dst Reg)

RshWide emits dst = src >> shift with high bits shifted from adj. It may modify the carry flag.

func (*Asm) SLTU 

func (a *Asm) SLTU(src1, src2, dst Reg)

SLTU emits dst = src2 < src1 (0 or 1), using an unsigned comparison.

func (*Asm) SaveCarry 

func (a *Asm) SaveCarry(dst Reg)

SaveCarry saves the carry flag into dst. The meaning of the bits in dst is architecture-dependent. The carry flag is left in an undefined state.

func (*Asm) SaveConvertCarry 

func (a *Asm) SaveConvertCarry(which Carry, dst Reg)

SaveConvertCarry saves and converts the carry flag into dst: 0 unset, 1 set. The carry flag is left in an undefined state.

func (*Asm) SetOption 

func (a *Asm) SetOption(option Option, on bool)

SetOption changes whether the optional CPU feature should be considered to be enabled.

func (*Asm) SetRegsUsed 

func (a *Asm) SetRegsUsed(used RegsUsed)

SetRegsUsed sets which registers are currently allocated. The argument should have been returned from a previous call to Asm.RegsUsed.

func (*Asm) Sub 

func (a *Asm) Sub(src1, src2, dst Reg, carry Carry)

Sub emits dst = src2-src1, with the specified carry behavior.

func (*Asm) Unfree 

func (a *Asm) Unfree(r Reg)

Unfree reallocates a previously freed register r. If r is not a register (if it's an immediate or a memory reference), Unfree is a no-op. If r is not free for allocation, Unfree panics. A Free paired with Unfree can release a register for use temporarily but then reclaim it, such as at the end of a loop body when it must be restored.

func (*Asm) Xor 

func (a *Asm) Xor(src1, src2, dst Reg)

Xor emits dst = src1 ^ src2 It may modify the carry flag.

func (*Asm) ZR 

func (a *Asm) ZR() Reg

ZR returns the zero register (the specific register guaranteed to hold the integer 0), or else the zero Reg (Reg{}, which has r.Valid() == false).

type Carry 

type Carry uint

A Carry is a flag field explaining how an instruction sets and uses the carry flags. Different operations expect different sets of bits. Add and Sub expect: UseCarry or 0, SetCarry, KeepCarry, or SmashCarry; and AltCarry or 0. ClearCarry, SaveCarry, and ConvertCarry expect: AddCarry or SubCarry; and AltCarry or 0. 

const (
	SetCarry   Carry = 1 << iota // sets carry
	UseCarry                     // uses carry
	KeepCarry                    // must preserve carry
	SmashCarry                   // can modify carry or not, whatever is easiest

	AltCarry // use the secondary carry flag
	AddCarry // use add carry flag semantics (for ClearCarry, ConvertCarry)
	SubCarry // use sub carry flag semantics (for ClearCarry, ConvertCarry)
)

type Func 

type Func struct {
	Name string
	Asm  *Asm
	// contains filtered or unexported fields
}

A Func represents a single assembly function.

func (*Func) Arg 

func (f *Func) Arg(name string) Reg

Arg allocates a new register, copies the named argument (or result) into it, and returns that register.

func (*Func) ArgHint 

func (f *Func) ArgHint(name string, hint Hint) Reg

ArgHint is like Arg but uses a register allocation hint.

func (*Func) ArgPtr 

func (f *Func) ArgPtr(name string) RegPtr

ArgPtr is like Arg but returns a RegPtr.

func (*Func) Pipe 

func (f *Func) Pipe() *Pipe

Pipe creates and returns a new pipe for use in the function f.

func (*Func) StoreArg 

func (f *Func) StoreArg(src Reg, name string)

StoreArg stores src into the named argument (or result).

type Hint 

type Hint uint

A Hint is a hint about what a register will be used for, so that an appropriate one can be selected. 

const (
	HintNone       Hint = iota
	HintShiftCount      // shift count (CX on x86)
	HintMulSrc          // mul source operand (AX on x86)
	HintMulHi           // wide mul high output (DX on x86)
	HintMemOK           // a memory reference is okay
	HintCarry           // carry flag
	HintAltCarry        // secondary carry flag
)

type Option 

type Option int

An Option denotes an optional CPU feature that can be tested at runtime. 

const (

	// OptionAltCarry checks whether there is an add instruction
	// that uses a secondary carry flag, so that two different sums
	// can be accumulated in parallel with independent carry flags.
	// Some architectures (MIPS, Loong64, RISC-V) provide this
	// functionality natively, indicated by asm.Carry().Valid() being true.
	OptionAltCarry Option
)

type Pipe 

type Pipe struct {
	// contains filtered or unexported fields
}

A Pipe manages the input and output data pipelines for a function's memory operations.

The input is one or more equal-length slices of words, so collectively it can be viewed as a matrix, in which each slice is a row and each column is a set of corresponding words from the different slices. The output can be viewed the same way, although it is often just one row.

func (*Pipe) AtUnrollEnd 

func (p *Pipe) AtUnrollEnd(end func())

AtUnrollEnd sets a function to call at the end of an unrolled sequence. See Pipe.Loop for details.

func (*Pipe) AtUnrollStart 

func (p *Pipe) AtUnrollStart(start func())

AtUnrollStart sets a function to call at the start of an unrolled sequence. See Pipe.Loop for details.

func (*Pipe) Done 

func (p *Pipe) Done()

Done frees all the registers allocated by the pipe.

func (*Pipe) DropInput 

func (p *Pipe) DropInput(name string)

DropInput deletes the named input from the pipe, usually because it has been exhausted. (This is not used yet but will be used in a future generator.)

func (*Pipe) LoadN 

func (p *Pipe) LoadN(n int) [][]Reg

LoadN returns the next n columns of input words as a slice of rows. Regs for inputs that have been marked using p.SetMemOK will be direct memory references. Regs for other inputs will be newly allocated registers and must be freed.

func (*Pipe) LoadPtrs 

func (p *Pipe) LoadPtrs(n Reg)

LoadPtrs loads the slice pointer arguments into registers, assuming that the slice length n has already been loaded into the register n.

Start will call LoadPtrs if it has not been called already. LoadPtrs only needs to be called explicitly when code needs to use LoadN before Start, like when the shift.go generators read an initial word before the loop.

func (*Pipe) Loop 

func (p *Pipe) Loop(block func(in, out [][]Reg))

Loop emits code for the loop, calling block repeatedly to emit code that handles a block of N input columns (for arbitrary N = len(in[0]) chosen by p). block must call p.StoreN(out) to write N output columns. The out slice is a pre-allocated matrix of uninitialized Reg values. block is expected to set each entry to the Reg that should be written before calling p.StoreN(out).

For example, if the loop is to be unrolled 4x in blocks of 2 columns each, the sequence of calls to emit the unrolled loop body is: 

start()  // set by pAtUnrollStart
... reads for 2 columns ...
block()
... writes for 2 columns ...
... reads for 2 columns ...
block()
... writes for 2 columns ...
end()  // set by p.AtUnrollEnd

Any registers allocated during block are freed automatically when block returns.

func (*Pipe) Restart 

func (p *Pipe) Restart(n Reg, factors ...int)

Restart prepares to loop over an additional n columns, beyond a previous loop run by p.Start/p.Loop.

func (*Pipe) SetBackward 

func (p *Pipe) SetBackward()

SetBackward sets the pipe to process the input and output columns in reverse order. This is needed for left shifts, which might otherwise overwrite data they will read later.

func (*Pipe) SetHint 

func (p *Pipe) SetHint(name string, hint Hint)

SetHint records that the inputs from the named vector should be allocated with the given register hint.

If the hint indicates a single register on the target architecture, then SetHint calls SetMaxColumns(1), since the hinted register can only be used for one value at a time.

func (*Pipe) SetLabel 

func (p *Pipe) SetLabel(label string)

SetLabel sets the label prefix for the loops emitted by the pipe. The default prefix is "loop".

func (*Pipe) SetMaxColumns 

func (p *Pipe) SetMaxColumns(m int)

SetMaxColumns sets the maximum number of columns processed in a single loop body call.

func (*Pipe) SetUseIndexCounter 

func (p *Pipe) SetUseIndexCounter()

SetUseIndexCounter sets the pipe to use an index counter if possible, meaning the loop counter is also used as an index for accessing the slice data. This clever trick is slower on modern processors, but it is still necessary on 386. On non-386 systems, SetUseIndexCounter is a no-op.

func (*Pipe) Start 

func (p *Pipe) Start(n Reg, factors ...int)

Start prepares to loop over n columns. The factors give a sequence of unrolling factors to use, which must be either strictly increasing or strictly decreasing and must include 1. For example, 4, 1 means to process 4 elements at a time and then 1 at a time for the final 0-3; specifying 1,4 instead handles 0-3 elements first and then 4 at a time. Similarly, 32, 4, 1 means to process 32 at a time, then 4 at a time, then 1 at a time.

One benefit of using 1, 4 instead of 4, 1 is that the body processing 4 at a time needs more registers, and if it is the final body, the register holding the fragment count (0-3) has been freed and is available for use.

Start may modify the carry flag.

Start must be followed by a call to Loop1 or LoopN, but it is permitted to emit other instructions first, for example to set an initial carry flag.

func (*Pipe) StoreN 

func (p *Pipe) StoreN(regs [][]Reg)

StoreN writes regs (a slice of rows) to the next n columns of output, where n = len(regs[0]).

type Reg 

type Reg struct {
	// contains filtered or unexported fields
}

A Reg is an allocated register or other assembly operand. (For example, a constant might have name "$123" and a memory reference might have name "0(R8)".)

func (Reg) IsImm 

func (r Reg) IsImm() bool

IsImm reports whether r is an immediate value.

func (Reg) IsMem 

func (r Reg) IsMem() bool

IsMem reports whether r is a memory value.

func (Reg) String 

func (r Reg) String() string

String returns the assembly syntax for r.

func (Reg) Valid 

func (r Reg) Valid() bool

Valid reports whether is valid, meaning r is not the zero value of Reg (a register with no name).

type RegPtr 

type RegPtr struct {
	// contains filtered or unexported fields
}

A RegPtr is like a Reg but expected to hold a pointer. The separate Go type helps keeps pointers and scalars separate and avoid mistakes; it is okay to convert to Reg as needed to use specific routines.

func (RegPtr) String 

func (r RegPtr) String() string

String returns the assembly syntax for r.

func (RegPtr) Valid 

func (r RegPtr) Valid() bool

Valid reports whether is valid, meaning r is not the zero value of RegPtr (a register with no name).

type RegsUsed 

type RegsUsed struct {
	// contains filtered or unexported fields
}

A RegsUsed is a snapshot of which registers are allocated.

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