[chore] Update gin to v1.9.0 (#1553)

vendor/github.com/twitchyliquid64/golang-asm/obj/x86/evex.go

@@ -0,0 +1,382 @@
+// Copyright 2018 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.
+
+package x86
+
+import (
+	"github.com/twitchyliquid64/golang-asm/obj"
+	"errors"
+	"fmt"
+	"strings"
+)
+
+// evexBits stores EVEX prefix info that is used during instruction encoding.
+type evexBits struct {
+	b1 byte // [W1mmLLpp]
+	b2 byte // [NNNbbZRS]
+
+	// Associated instruction opcode.
+	opcode byte
+}
+
+// newEVEXBits creates evexBits object from enc bytes at z position.
+func newEVEXBits(z int, enc *opBytes) evexBits {
+	return evexBits{
+		b1:     enc[z+0],
+		b2:     enc[z+1],
+		opcode: enc[z+2],
+	}
+}
+
+// P returns EVEX.pp value.
+func (evex evexBits) P() byte { return (evex.b1 & evexP) >> 0 }
+
+// L returns EVEX.L'L value.
+func (evex evexBits) L() byte { return (evex.b1 & evexL) >> 2 }
+
+// M returns EVEX.mm value.
+func (evex evexBits) M() byte { return (evex.b1 & evexM) >> 4 }
+
+// W returns EVEX.W value.
+func (evex evexBits) W() byte { return (evex.b1 & evexW) >> 7 }
+
+// BroadcastEnabled reports whether BCST suffix is permitted.
+func (evex evexBits) BroadcastEnabled() bool {
+	return evex.b2&evexBcst != 0
+}
+
+// ZeroingEnabled reports whether Z suffix is permitted.
+func (evex evexBits) ZeroingEnabled() bool {
+	return (evex.b2&evexZeroing)>>2 != 0
+}
+
+// RoundingEnabled reports whether RN_SAE, RZ_SAE, RD_SAE and RU_SAE suffixes
+// are permitted.
+func (evex evexBits) RoundingEnabled() bool {
+	return (evex.b2&evexRounding)>>1 != 0
+}
+
+// SaeEnabled reports whether SAE suffix is permitted.
+func (evex evexBits) SaeEnabled() bool {
+	return (evex.b2&evexSae)>>0 != 0
+}
+
+// DispMultiplier returns displacement multiplier that is calculated
+// based on tuple type, EVEX.W and input size.
+// If embedded broadcast is used, bcst should be true.
+func (evex evexBits) DispMultiplier(bcst bool) int32 {
+	if bcst {
+		switch evex.b2 & evexBcst {
+		case evexBcstN4:
+			return 4
+		case evexBcstN8:
+			return 8
+		}
+		return 1
+	}
+
+	switch evex.b2 & evexN {
+	case evexN1:
+		return 1
+	case evexN2:
+		return 2
+	case evexN4:
+		return 4
+	case evexN8:
+		return 8
+	case evexN16:
+		return 16
+	case evexN32:
+		return 32
+	case evexN64:
+		return 64
+	case evexN128:
+		return 128
+	}
+	return 1
+}
+
+// EVEX is described by using 2-byte sequence.
+// See evexBits for more details.
+const (
+	evexW   = 0x80 // b1[W... ....]
+	evexWIG = 0 << 7
+	evexW0  = 0 << 7
+	evexW1  = 1 << 7
+
+	evexM    = 0x30 // b2[..mm ...]
+	evex0F   = 1 << 4
+	evex0F38 = 2 << 4
+	evex0F3A = 3 << 4
+
+	evexL   = 0x0C // b1[.... LL..]
+	evexLIG = 0 << 2
+	evex128 = 0 << 2
+	evex256 = 1 << 2
+	evex512 = 2 << 2
+
+	evexP  = 0x03 // b1[.... ..pp]
+	evex66 = 1 << 0
+	evexF3 = 2 << 0
+	evexF2 = 3 << 0
+
+	// Precalculated Disp8 N value.
+	// N acts like a multiplier for 8bit displacement.
+	// Note that some N are not used, but their bits are reserved.
+	evexN    = 0xE0 // b2[NNN. ....]
+	evexN1   = 0 << 5
+	evexN2   = 1 << 5
+	evexN4   = 2 << 5
+	evexN8   = 3 << 5
+	evexN16  = 4 << 5
+	evexN32  = 5 << 5
+	evexN64  = 6 << 5
+	evexN128 = 7 << 5
+
+	// Disp8 for broadcasts.
+	evexBcst   = 0x18 // b2[...b b...]
+	evexBcstN4 = 1 << 3
+	evexBcstN8 = 2 << 3
+
+	// Flags that permit certain AVX512 features.
+	// It's semantically illegal to combine evexZeroing and evexSae.
+	evexZeroing         = 0x4 // b2[.... .Z..]
+	evexZeroingEnabled  = 1 << 2
+	evexRounding        = 0x2 // b2[.... ..R.]
+	evexRoundingEnabled = 1 << 1
+	evexSae             = 0x1 // b2[.... ...S]
+	evexSaeEnabled      = 1 << 0
+)
+
+// compressedDisp8 calculates EVEX compressed displacement, if applicable.
+func compressedDisp8(disp, elemSize int32) (disp8 byte, ok bool) {
+	if disp%elemSize == 0 {
+		v := disp / elemSize
+		if v >= -128 && v <= 127 {
+			return byte(v), true
+		}
+	}
+	return 0, false
+}
+
+// evexZcase reports whether given Z-case belongs to EVEX group.
+func evexZcase(zcase uint8) bool {
+	return zcase > Zevex_first && zcase < Zevex_last
+}
+
+// evexSuffixBits carries instruction EVEX suffix set flags.
+//
+// Examples:
+//	"RU_SAE.Z" => {rounding: 3, zeroing: true}
+//	"Z" => {zeroing: true}
+//	"BCST" => {broadcast: true}
+//	"SAE.Z" => {sae: true, zeroing: true}
+type evexSuffix struct {
+	rounding  byte
+	sae       bool
+	zeroing   bool
+	broadcast bool
+}
+
+// Rounding control values.
+// Match exact value for EVEX.L'L field (with exception of rcUnset).
+const (
+	rcRNSAE = 0 // Round towards nearest
+	rcRDSAE = 1 // Round towards -Inf
+	rcRUSAE = 2 // Round towards +Inf
+	rcRZSAE = 3 // Round towards zero
+	rcUnset = 4
+)
+
+// newEVEXSuffix returns proper zero value for evexSuffix.
+func newEVEXSuffix() evexSuffix {
+	return evexSuffix{rounding: rcUnset}
+}
+
+// evexSuffixMap maps obj.X86suffix to its decoded version.
+// Filled during init().
+var evexSuffixMap [255]evexSuffix
+
+func init() {
+	// Decode all valid suffixes for later use.
+	for i := range opSuffixTable {
+		suffix := newEVEXSuffix()
+		parts := strings.Split(opSuffixTable[i], ".")
+		for j := range parts {
+			switch parts[j] {
+			case "Z":
+				suffix.zeroing = true
+			case "BCST":
+				suffix.broadcast = true
+			case "SAE":
+				suffix.sae = true
+
+			case "RN_SAE":
+				suffix.rounding = rcRNSAE
+			case "RD_SAE":
+				suffix.rounding = rcRDSAE
+			case "RU_SAE":
+				suffix.rounding = rcRUSAE
+			case "RZ_SAE":
+				suffix.rounding = rcRZSAE
+			}
+		}
+		evexSuffixMap[i] = suffix
+	}
+}
+
+// toDisp8 tries to convert disp to proper 8-bit displacement value.
+func toDisp8(disp int32, p *obj.Prog, asmbuf *AsmBuf) (disp8 byte, ok bool) {
+	if asmbuf.evexflag {
+		bcst := evexSuffixMap[p.Scond].broadcast
+		elemSize := asmbuf.evex.DispMultiplier(bcst)
+		return compressedDisp8(disp, elemSize)
+	}
+	return byte(disp), disp >= -128 && disp < 128
+}
+
+// EncodeRegisterRange packs [reg0-reg1] list into 64-bit value that
+// is intended to be stored inside obj.Addr.Offset with TYPE_REGLIST.
+func EncodeRegisterRange(reg0, reg1 int16) int64 {
+	return (int64(reg0) << 0) |
+		(int64(reg1) << 16) |
+		obj.RegListX86Lo
+}
+
+// decodeRegisterRange unpacks [reg0-reg1] list from 64-bit value created by EncodeRegisterRange.
+func decodeRegisterRange(list int64) (reg0, reg1 int) {
+	return int((list >> 0) & 0xFFFF),
+		int((list >> 16) & 0xFFFF)
+}
+
+// ParseSuffix handles the special suffix for the 386/AMD64.
+// Suffix bits are stored into p.Scond.
+//
+// Leading "." in cond is ignored.
+func ParseSuffix(p *obj.Prog, cond string) error {
+	cond = strings.TrimPrefix(cond, ".")
+
+	suffix := newOpSuffix(cond)
+	if !suffix.IsValid() {
+		return inferSuffixError(cond)
+	}
+
+	p.Scond = uint8(suffix)
+	return nil
+}
+
+// inferSuffixError returns non-nil error that describes what could be
+// the cause of suffix parse failure.
+//
+// At the point this function is executed there is already assembly error,
+// so we can burn some clocks to construct good error message.
+//
+// Reported issues:
+//	- duplicated suffixes
+//	- illegal rounding/SAE+broadcast combinations
+//	- unknown suffixes
+//	- misplaced suffix (e.g. wrong Z suffix position)
+func inferSuffixError(cond string) error {
+	suffixSet := make(map[string]bool)  // Set for duplicates detection.
+	unknownSet := make(map[string]bool) // Set of unknown suffixes.
+	hasBcst := false
+	hasRoundSae := false
+	var msg []string // Error message parts
+
+	suffixes := strings.Split(cond, ".")
+	for i, suffix := range suffixes {
+		switch suffix {
+		case "Z":
+			if i != len(suffixes)-1 {
+				msg = append(msg, "Z suffix should be the last")
+			}
+		case "BCST":
+			hasBcst = true
+		case "SAE", "RN_SAE", "RZ_SAE", "RD_SAE", "RU_SAE":
+			hasRoundSae = true
+		default:
+			if !unknownSet[suffix] {
+				msg = append(msg, fmt.Sprintf("unknown suffix %q", suffix))
+			}
+			unknownSet[suffix] = true
+		}
+
+		if suffixSet[suffix] {
+			msg = append(msg, fmt.Sprintf("duplicate suffix %q", suffix))
+		}
+		suffixSet[suffix] = true
+	}
+
+	if hasBcst && hasRoundSae {
+		msg = append(msg, "can't combine rounding/SAE and broadcast")
+	}
+
+	if len(msg) == 0 {
+		return errors.New("bad suffix combination")
+	}
+	return errors.New(strings.Join(msg, "; "))
+}
+
+// opSuffixTable is a complete list of possible opcode suffix combinations.
+// It "maps" uint8 suffix bits to their string representation.
+// With the exception of first and last elements, order is not important.
+var opSuffixTable = [...]string{
+	"", // Map empty suffix to empty string.
+
+	"Z",
+
+	"SAE",
+	"SAE.Z",
+
+	"RN_SAE",
+	"RZ_SAE",
+	"RD_SAE",
+	"RU_SAE",
+	"RN_SAE.Z",
+	"RZ_SAE.Z",
+	"RD_SAE.Z",
+	"RU_SAE.Z",
+
+	"BCST",
+	"BCST.Z",
+
+	"<bad suffix>",
+}
+
+// opSuffix represents instruction opcode suffix.
+// Compound (multi-part) suffixes expressed with single opSuffix value.
+//
+// uint8 type is used to fit obj.Prog.Scond.
+type opSuffix uint8
+
+// badOpSuffix is used to represent all invalid suffix combinations.
+const badOpSuffix = opSuffix(len(opSuffixTable) - 1)
+
+// newOpSuffix returns opSuffix object that matches suffixes string.
+//
+// If no matching suffix is found, special "invalid" suffix is returned.
+// Use IsValid method to check against this case.
+func newOpSuffix(suffixes string) opSuffix {
+	for i := range opSuffixTable {
+		if opSuffixTable[i] == suffixes {
+			return opSuffix(i)
+		}
+	}
+	return badOpSuffix
+}
+
+// IsValid reports whether suffix is valid.
+// Empty suffixes are valid.
+func (suffix opSuffix) IsValid() bool {
+	return suffix != badOpSuffix
+}
+
+// String returns suffix printed representation.
+//
+// It matches the string that was used to create suffix with NewX86Suffix()
+// for valid suffixes.
+// For all invalid suffixes, special marker is returned.
+func (suffix opSuffix) String() string {
+	return opSuffixTable[suffix]
+}