102 lines
2.8 KiB
Go
102 lines
2.8 KiB
Go
// Copyright (c) 2026 Petr Balvín <opensource@petrbalvin.org> (https://petrbalvin.org)
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// SPDX-License-Identifier: BSD-3-Clause
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package asm
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import "strings"
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// Encodable reports whether the amd64 encoder knows how to encode the
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// mnemonic. It mirrors the dispatch in (*enc).encode: the fixed-name
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// instructions, conditional jumps, the CMOV/SET condition families, the
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// VEX/EVEX/opmask/gather/scatter vector paths, the legacy SSE tables and the
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// explicit scalar cases. A mnemonic that parses (is in the architecture
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// table) but is not encodable would otherwise surface only at assembly time,
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// deep inside a build; the linter uses this predicate to flag it at edit
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// time.
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func Encodable(mnemonic string) bool {
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upper := strings.ToUpper(mnemonic)
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// Fixed-name instructions (no size suffix).
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switch upper {
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case "RET", "NOP", "CALL", "JMP":
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return true
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}
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if _, ok := condCode(upper); ok {
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return true
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}
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// VEX/EVEX and friends: the trailing B/W/L/Q/D is part of the mnemonic.
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base, _, err := parseEvexSuffix(upper)
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if err != nil {
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return false
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}
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if isVex(base) || isEvex(base) || isKOp(base) || isGather(base) || isScatter(base) ||
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base == "KMOVW" || base == "KMOVQ" {
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return true
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}
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// CMOV carries size then condition (CMOVLGT); SET carries the condition
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// alone (SETNE). The size letter is checked exactly as encodeCmov does,
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// so a spelling like CMOVBGT is not reported encodable when Encode
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// would reject it.
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if rest, ok := strings.CutPrefix(upper, "CMOV"); ok && len(rest) >= 2 {
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switch rest[0] {
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case 'W', 'L', 'Q':
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if _, ok := jccMap[rest[1:]]; ok {
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return true
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}
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}
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}
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if rest, ok := strings.CutPrefix(upper, "SET"); ok {
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if _, ok := jccMap[rest]; ok {
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return true
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}
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}
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// Legacy SSE shuffles and packed binaries dispatch on the full name.
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if _, ok := sseShufTable[upper]; ok {
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return true
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}
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if _, ok := sseBinTable[upper]; ok {
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return true
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}
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// The size-suffix split: retry the tables and the scalar switch on the
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// base.
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base2, size := splitSize(upper)
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if size == 0 {
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size = 8
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}
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_ = size
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if base2 != upper {
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if _, ok := sseBinTable[base2]; ok {
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return true
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}
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}
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switch base2 {
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case "MOV",
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"ADD", "SUB", "AND", "OR", "XOR", "CMP",
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"TEST",
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"LEA",
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"INC", "DEC", "NEG", "NOT",
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"SHL", "SHR", "SAR",
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"IMUL", "IMUL3",
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"PUSH", "POP",
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"BSF", "BSR", "LZCNT", "TZCNT", "POPCNT",
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"BSWAP",
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"PREFETCHNTA", "PREFETCHT0", "PREFETCHT1", "PREFETCHT2",
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"MOVBLZX", "MOVBQZX", "MOVWLZX", "MOVWQZX", "MOVWLSX", "MOVLQSX",
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"MOVBWZX", "MOVBWSX", "MOVBLSX", "MOVBQSX", "MOVWQSX", "MOVLQZX",
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"CVTSL2SD", "CVTSQ2SD",
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"MOVOU", "MOVO", "MOVUPS", "MOVAPS", "MOVUPD", "MOVAPD", "MOVSD", "MOVSS":
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return true
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}
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// Full-name dispatches the size split would eat (a trailing width
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// letter that is part of the mnemonic).
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switch upper {
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case "PMOVMSKB":
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return true
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}
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return false
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}
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