Files
wasmtime/cranelift/codegen/src/isa/x64/inst/mod.rs

906 lines
26 KiB
Rust

//! This module defines x86_64-specific machine instruction types.
#![allow(dead_code)]
#![allow(non_snake_case)]
#![allow(non_camel_case_types)]
use core::convert::TryFrom;
use smallvec::SmallVec;
use std::fmt;
use std::string::{String, ToString};
use regalloc::RegUsageCollector;
use regalloc::Set;
use regalloc::{RealRegUniverse, Reg, RegClass, RegUsageMapper, SpillSlot, VirtualReg, Writable};
use crate::binemit::CodeOffset;
use crate::ir::types::{B1, B128, B16, B32, B64, B8, F32, F64, I128, I16, I32, I64, I8};
use crate::ir::ExternalName;
use crate::ir::Type;
use crate::machinst::*;
use crate::settings::Flags;
use crate::{settings, CodegenError, CodegenResult};
pub mod args;
mod emit;
#[cfg(test)]
mod emit_tests;
pub mod regs;
use args::*;
use regs::{create_reg_universe_systemv, show_ireg_sized};
//=============================================================================
// Instructions (top level): definition
// Don't build these directly. Instead use the Inst:: functions to create them.
/// Instructions. Destinations are on the RIGHT (a la AT&T syntax).
#[derive(Clone)]
pub(crate) enum Inst {
/// nops of various sizes, including zero
Nop { len: u8 },
/// (add sub and or xor mul adc? sbb?) (32 64) (reg addr imm) reg
Alu_RMI_R {
is_64: bool,
op: RMI_R_Op,
src: RMI,
dst: Writable<Reg>,
},
/// (imm32 imm64) reg.
/// Either: movl $imm32, %reg32 or movabsq $imm64, %reg32
Imm_R {
dst_is_64: bool,
simm64: u64,
dst: Writable<Reg>,
},
/// mov (64 32) reg reg
Mov_R_R {
is_64: bool,
src: Reg,
dst: Writable<Reg>,
},
/// movz (bl bq wl wq lq) addr reg (good for all ZX loads except 64->64).
/// Note that the lq variant doesn't really exist since the default
/// zero-extend rule makes it unnecessary. For that case we emit the
/// equivalent "movl AM, reg32".
MovZX_M_R {
extMode: ExtMode,
addr: Addr,
dst: Writable<Reg>,
},
/// A plain 64-bit integer load, since MovZX_M_R can't represent that
Mov64_M_R { addr: Addr, dst: Writable<Reg> },
/// movs (bl bq wl wq lq) addr reg (good for all SX loads)
MovSX_M_R {
extMode: ExtMode,
addr: Addr,
dst: Writable<Reg>,
},
/// mov (b w l q) reg addr (good for all integer stores)
Mov_R_M {
size: u8, // 1, 2, 4 or 8
src: Reg,
addr: Addr,
},
/// (shl shr sar) (l q) imm reg
Shift_R {
is_64: bool,
kind: ShiftKind,
/// shift count: Some(0 .. #bits-in-type - 1), or None to mean "%cl".
num_bits: Option<u8>,
dst: Writable<Reg>,
},
/// cmp (b w l q) (reg addr imm) reg
Cmp_RMI_R {
size: u8, // 1, 2, 4 or 8
src: RMI,
dst: Reg,
},
/// pushq (reg addr imm)
Push64 { src: RMI },
/// popq reg
Pop64 { dst: Writable<Reg> },
/// call simm32
CallKnown {
dest: ExternalName,
uses: Set<Reg>,
defs: Set<Writable<Reg>>,
},
/// callq (reg mem)
CallUnknown {
dest: RM,
//uses: Set<Reg>,
//defs: Set<Writable<Reg>>,
},
// ---- branches (exactly one must appear at end of BB) ----
/// ret
Ret,
/// A placeholder instruction, generating no code, meaning that a function epilogue must be
/// inserted there.
EpiloguePlaceholder,
/// jmp simm32
JmpKnown { dest: BranchTarget },
/// jcond cond target target
/// Symmetrical two-way conditional branch.
/// Emitted as a compound sequence; the MachBuffer will shrink it
/// as appropriate.
JmpCondSymm {
cc: CC,
taken: BranchTarget,
not_taken: BranchTarget,
},
/// jmpq (reg mem)
JmpUnknown { target: RM },
}
// Handy constructors for Insts.
// For various sizes, will some number of lowest bits sign extend to be the
// same as the whole value?
pub(crate) fn low32willSXto64(x: u64) -> bool {
let xs = x as i64;
xs == ((xs << 32) >> 32)
}
impl Inst {
pub(crate) fn nop(len: u8) -> Self {
debug_assert!(len <= 16);
Self::Nop { len }
}
pub(crate) fn alu_rmi_r(is_64: bool, op: RMI_R_Op, src: RMI, dst: Writable<Reg>) -> Self {
debug_assert!(dst.to_reg().get_class() == RegClass::I64);
Self::Alu_RMI_R {
is_64,
op,
src,
dst,
}
}
pub(crate) fn imm_r(dst_is_64: bool, simm64: u64, dst: Writable<Reg>) -> Inst {
debug_assert!(dst.to_reg().get_class() == RegClass::I64);
if !dst_is_64 {
debug_assert!(low32willSXto64(simm64));
}
Inst::Imm_R {
dst_is_64,
simm64,
dst,
}
}
pub(crate) fn mov_r_r(is_64: bool, src: Reg, dst: Writable<Reg>) -> Inst {
debug_assert!(src.get_class() == RegClass::I64);
debug_assert!(dst.to_reg().get_class() == RegClass::I64);
Inst::Mov_R_R { is_64, src, dst }
}
pub(crate) fn movzx_m_r(extMode: ExtMode, addr: Addr, dst: Writable<Reg>) -> Inst {
debug_assert!(dst.to_reg().get_class() == RegClass::I64);
Inst::MovZX_M_R { extMode, addr, dst }
}
pub(crate) fn mov64_m_r(addr: Addr, dst: Writable<Reg>) -> Inst {
debug_assert!(dst.to_reg().get_class() == RegClass::I64);
Inst::Mov64_M_R { addr, dst }
}
pub(crate) fn movsx_m_r(extMode: ExtMode, addr: Addr, dst: Writable<Reg>) -> Inst {
debug_assert!(dst.to_reg().get_class() == RegClass::I64);
Inst::MovSX_M_R { extMode, addr, dst }
}
pub(crate) fn mov_r_m(
size: u8, // 1, 2, 4 or 8
src: Reg,
addr: Addr,
) -> Inst {
debug_assert!(size == 8 || size == 4 || size == 2 || size == 1);
debug_assert!(src.get_class() == RegClass::I64);
Inst::Mov_R_M { size, src, addr }
}
pub(crate) fn shift_r(
is_64: bool,
kind: ShiftKind,
num_bits: Option<u8>,
dst: Writable<Reg>,
) -> Inst {
debug_assert!(if let Some(num_bits) = num_bits {
num_bits < if is_64 { 64 } else { 32 }
} else {
true
});
debug_assert!(dst.to_reg().get_class() == RegClass::I64);
Inst::Shift_R {
is_64,
kind,
num_bits,
dst,
}
}
pub(crate) fn cmp_rmi_r(
size: u8, // 1, 2, 4 or 8
src: RMI,
dst: Reg,
) -> Inst {
debug_assert!(size == 8 || size == 4 || size == 2 || size == 1);
debug_assert!(dst.get_class() == RegClass::I64);
Inst::Cmp_RMI_R { size, src, dst }
}
pub(crate) fn push64(src: RMI) -> Inst {
Inst::Push64 { src }
}
pub(crate) fn pop64(dst: Writable<Reg>) -> Inst {
Inst::Pop64 { dst }
}
pub(crate) fn call_unknown(dest: RM) -> Inst {
Inst::CallUnknown { dest }
}
pub(crate) fn ret() -> Inst {
Inst::Ret
}
pub(crate) fn epilogue_placeholder() -> Inst {
Inst::EpiloguePlaceholder
}
pub(crate) fn jmp_known(dest: BranchTarget) -> Inst {
Inst::JmpKnown { dest }
}
pub(crate) fn jmp_cond_symm(cc: CC, taken: BranchTarget, not_taken: BranchTarget) -> Inst {
Inst::JmpCondSymm {
cc,
taken,
not_taken,
}
}
pub(crate) fn jmp_unknown(target: RM) -> Inst {
Inst::JmpUnknown { target }
}
}
//=============================================================================
// Instructions: printing
impl ShowWithRRU for Inst {
fn show_rru(&self, mb_rru: Option<&RealRegUniverse>) -> String {
fn ljustify(s: String) -> String {
let w = 7;
if s.len() >= w {
s
} else {
let need = usize::min(w, w - s.len());
s + &format!("{nil: <width$}", nil = "", width = need)
}
}
fn ljustify2(s1: String, s2: String) -> String {
ljustify(s1 + &s2)
}
fn suffixLQ(is_64: bool) -> String {
(if is_64 { "q" } else { "l" }).to_string()
}
fn sizeLQ(is_64: bool) -> u8 {
if is_64 {
8
} else {
4
}
}
fn suffixBWLQ(size: u8) -> String {
match size {
1 => "b".to_string(),
2 => "w".to_string(),
4 => "l".to_string(),
8 => "q".to_string(),
_ => panic!("Inst(x64).show.suffixBWLQ: size={}", size),
}
}
match self {
Inst::Nop { len } => format!("{} len={}", ljustify("nop".to_string()), len),
Inst::Alu_RMI_R {
is_64,
op,
src,
dst,
} => format!(
"{} {}, {}",
ljustify2(op.to_string(), suffixLQ(*is_64)),
src.show_rru_sized(mb_rru, sizeLQ(*is_64)),
show_ireg_sized(dst.to_reg(), mb_rru, sizeLQ(*is_64)),
),
Inst::Imm_R {
dst_is_64,
simm64,
dst,
} => {
if *dst_is_64 {
format!(
"{} ${}, {}",
ljustify("movabsq".to_string()),
*simm64 as i64,
show_ireg_sized(dst.to_reg(), mb_rru, 8)
)
} else {
format!(
"{} ${}, {}",
ljustify("movl".to_string()),
(*simm64 as u32) as i32,
show_ireg_sized(dst.to_reg(), mb_rru, 4)
)
}
}
Inst::Mov_R_R { is_64, src, dst } => format!(
"{} {}, {}",
ljustify2("mov".to_string(), suffixLQ(*is_64)),
show_ireg_sized(*src, mb_rru, sizeLQ(*is_64)),
show_ireg_sized(dst.to_reg(), mb_rru, sizeLQ(*is_64))
),
Inst::MovZX_M_R { extMode, addr, dst } => {
if *extMode == ExtMode::LQ {
format!(
"{} {}, {}",
ljustify("movl".to_string()),
addr.show_rru(mb_rru),
show_ireg_sized(dst.to_reg(), mb_rru, 4)
)
} else {
format!(
"{} {}, {}",
ljustify2("movz".to_string(), extMode.to_string()),
addr.show_rru(mb_rru),
show_ireg_sized(dst.to_reg(), mb_rru, extMode.dst_size())
)
}
}
Inst::Mov64_M_R { addr, dst } => format!(
"{} {}, {}",
ljustify("movq".to_string()),
addr.show_rru(mb_rru),
dst.show_rru(mb_rru)
),
Inst::MovSX_M_R { extMode, addr, dst } => format!(
"{} {}, {}",
ljustify2("movs".to_string(), extMode.to_string()),
addr.show_rru(mb_rru),
show_ireg_sized(dst.to_reg(), mb_rru, extMode.dst_size())
),
Inst::Mov_R_M { size, src, addr } => format!(
"{} {}, {}",
ljustify2("mov".to_string(), suffixBWLQ(*size)),
show_ireg_sized(*src, mb_rru, *size),
addr.show_rru(mb_rru)
),
Inst::Shift_R {
is_64,
kind,
num_bits,
dst,
} => match num_bits {
None => format!(
"{} %cl, {}",
ljustify2(kind.to_string(), suffixLQ(*is_64)),
show_ireg_sized(dst.to_reg(), mb_rru, sizeLQ(*is_64))
),
Some(num_bits) => format!(
"{} ${}, {}",
ljustify2(kind.to_string(), suffixLQ(*is_64)),
num_bits,
show_ireg_sized(dst.to_reg(), mb_rru, sizeLQ(*is_64))
),
},
Inst::Cmp_RMI_R { size, src, dst } => format!(
"{} {}, {}",
ljustify2("cmp".to_string(), suffixBWLQ(*size)),
src.show_rru_sized(mb_rru, *size),
show_ireg_sized(*dst, mb_rru, *size)
),
Inst::Push64 { src } => {
format!("{} {}", ljustify("pushq".to_string()), src.show_rru(mb_rru))
}
Inst::Pop64 { dst } => {
format!("{} {}", ljustify("popq".to_string()), dst.show_rru(mb_rru))
}
//Inst::CallKnown { target } => format!("{} {:?}", ljustify("call".to_string()), target),
Inst::CallKnown { .. } => "**CallKnown**".to_string(),
Inst::CallUnknown { dest } => format!(
"{} *{}",
ljustify("call".to_string()),
dest.show_rru(mb_rru)
),
Inst::Ret => "ret".to_string(),
Inst::EpiloguePlaceholder => "epilogue placeholder".to_string(),
Inst::JmpKnown { dest } => {
format!("{} {}", ljustify("jmp".to_string()), dest.show_rru(mb_rru))
}
Inst::JmpCondSymm {
cc,
taken,
not_taken,
} => format!(
"{} taken={} not_taken={}",
ljustify2("j".to_string(), cc.to_string()),
taken.show_rru(mb_rru),
not_taken.show_rru(mb_rru)
),
//
Inst::JmpUnknown { target } => format!(
"{} *{}",
ljustify("jmp".to_string()),
target.show_rru(mb_rru)
),
}
}
}
// Temp hook for legacy printing machinery
impl fmt::Debug for Inst {
fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
// Print the insn without a Universe :-(
write!(fmt, "{}", self.show_rru(None))
}
}
fn x64_get_regs(inst: &Inst, collector: &mut RegUsageCollector) {
// This is a bit subtle. If some register is in the modified set, then it may not be in either
// the use or def sets. However, enforcing that directly is somewhat difficult. Instead,
// regalloc.rs will "fix" this for us by removing the the modified set from the use and def
// sets.
match inst {
// ** Nop
Inst::Alu_RMI_R {
is_64: _,
op: _,
src,
dst,
} => {
src.get_regs_as_uses(collector);
collector.add_mod(*dst);
}
Inst::Imm_R {
dst_is_64: _,
simm64: _,
dst,
} => {
collector.add_def(*dst);
}
Inst::Mov_R_R { is_64: _, src, dst } => {
collector.add_use(*src);
collector.add_def(*dst);
}
Inst::MovZX_M_R {
extMode: _,
addr,
dst,
} => {
addr.get_regs_as_uses(collector);
collector.add_def(*dst);
}
Inst::Mov64_M_R { addr, dst } => {
addr.get_regs_as_uses(collector);
collector.add_def(*dst);
}
Inst::MovSX_M_R {
extMode: _,
addr,
dst,
} => {
addr.get_regs_as_uses(collector);
collector.add_def(*dst);
}
Inst::Mov_R_M { size: _, src, addr } => {
collector.add_use(*src);
addr.get_regs_as_uses(collector);
}
Inst::Shift_R {
is_64: _,
kind: _,
num_bits,
dst,
} => {
if num_bits.is_none() {
collector.add_use(regs::rcx());
}
collector.add_mod(*dst);
}
Inst::Cmp_RMI_R { size: _, src, dst } => {
src.get_regs_as_uses(collector);
collector.add_use(*dst); // yes, really `add_use`
}
Inst::Push64 { src } => {
src.get_regs_as_uses(collector);
collector.add_mod(Writable::from_reg(regs::rsp()));
}
Inst::Pop64 { dst } => {
collector.add_def(*dst);
}
Inst::CallKnown {
dest: _,
uses: _,
defs: _,
} => {
// FIXME add arg regs (iru.used) and caller-saved regs (iru.defined)
unimplemented!();
}
Inst::CallUnknown { dest } => {
dest.get_regs_as_uses(collector);
}
Inst::Ret => {}
Inst::EpiloguePlaceholder => {}
Inst::JmpKnown { dest: _ } => {}
Inst::JmpCondSymm {
cc: _,
taken: _,
not_taken: _,
} => {}
//Inst::JmpUnknown { target } => {
// target.get_regs_as_uses(collector);
//}
Inst::Nop { .. } | Inst::JmpUnknown { .. } => unimplemented!("x64_get_regs inst"),
}
}
//=============================================================================
// Instructions and subcomponents: map_regs
fn map_use<RUM: RegUsageMapper>(m: &RUM, r: &mut Reg) {
if r.is_virtual() {
let new = m.get_use(r.to_virtual_reg()).unwrap().to_reg();
*r = new;
}
}
fn map_def<RUM: RegUsageMapper>(m: &RUM, r: &mut Writable<Reg>) {
if r.to_reg().is_virtual() {
let new = m.get_def(r.to_reg().to_virtual_reg()).unwrap().to_reg();
*r = Writable::from_reg(new);
}
}
fn map_mod<RUM: RegUsageMapper>(m: &RUM, r: &mut Writable<Reg>) {
if r.to_reg().is_virtual() {
let new = m.get_mod(r.to_reg().to_virtual_reg()).unwrap().to_reg();
*r = Writable::from_reg(new);
}
}
impl Addr {
fn map_uses<RUM: RegUsageMapper>(&mut self, map: &RUM) {
match self {
Addr::IR {
simm32: _,
ref mut base,
} => map_use(map, base),
Addr::IRRS {
simm32: _,
ref mut base,
ref mut index,
shift: _,
} => {
map_use(map, base);
map_use(map, index);
}
}
}
}
impl RMI {
fn map_uses<RUM: RegUsageMapper>(&mut self, map: &RUM) {
match self {
RMI::R { ref mut reg } => map_use(map, reg),
RMI::M { ref mut addr } => addr.map_uses(map),
RMI::I { simm32: _ } => {}
}
}
}
impl RM {
fn map_uses<RUM: RegUsageMapper>(&mut self, map: &RUM) {
match self {
RM::R { ref mut reg } => map_use(map, reg),
RM::M { ref mut addr } => addr.map_uses(map),
}
}
}
fn x64_map_regs<RUM: RegUsageMapper>(inst: &mut Inst, mapper: &RUM) {
// Note this must be carefully synchronized with x64_get_regs.
match inst {
// ** Nop
Inst::Alu_RMI_R {
is_64: _,
op: _,
ref mut src,
ref mut dst,
} => {
src.map_uses(mapper);
map_mod(mapper, dst);
}
Inst::Imm_R {
dst_is_64: _,
simm64: _,
ref mut dst,
} => map_def(mapper, dst),
Inst::Mov_R_R {
is_64: _,
ref mut src,
ref mut dst,
} => {
map_use(mapper, src);
map_def(mapper, dst);
}
Inst::MovZX_M_R {
extMode: _,
ref mut addr,
ref mut dst,
} => {
addr.map_uses(mapper);
map_def(mapper, dst);
}
Inst::Mov64_M_R { addr, dst } => {
addr.map_uses(mapper);
map_def(mapper, dst);
}
Inst::MovSX_M_R {
extMode: _,
ref mut addr,
ref mut dst,
} => {
addr.map_uses(mapper);
map_def(mapper, dst);
}
Inst::Mov_R_M {
size: _,
ref mut src,
ref mut addr,
} => {
map_use(mapper, src);
addr.map_uses(mapper);
}
Inst::Shift_R {
is_64: _,
kind: _,
num_bits: _,
ref mut dst,
} => {
map_mod(mapper, dst);
}
Inst::Cmp_RMI_R {
size: _,
ref mut src,
ref mut dst,
} => {
src.map_uses(mapper);
map_use(mapper, dst);
}
Inst::Push64 { ref mut src } => src.map_uses(mapper),
Inst::Pop64 { ref mut dst } => {
map_def(mapper, dst);
}
Inst::CallKnown {
dest: _,
uses: _,
defs: _,
} => {}
Inst::CallUnknown { dest } => dest.map_uses(mapper),
Inst::Ret => {}
Inst::EpiloguePlaceholder => {}
Inst::JmpKnown { dest: _ } => {}
Inst::JmpCondSymm {
cc: _,
taken: _,
not_taken: _,
} => {}
//Inst::JmpUnknown { target } => {
// target.apply_map(mapper);
//}
Inst::Nop { .. } | Inst::JmpUnknown { .. } => unimplemented!("x64_map_regs opcode"),
}
}
//=============================================================================
// Instructions: misc functions and external interface
impl MachInst for Inst {
fn get_regs(&self, collector: &mut RegUsageCollector) {
x64_get_regs(&self, collector)
}
fn map_regs<RUM: RegUsageMapper>(&mut self, mapper: &RUM) {
x64_map_regs(self, mapper);
}
fn is_move(&self) -> Option<(Writable<Reg>, Reg)> {
// Note (carefully!) that a 32-bit mov *isn't* a no-op since it zeroes
// out the upper 32 bits of the destination. For example, we could
// conceivably use `movl %reg, %reg` to zero out the top 32 bits of
// %reg.
match self {
Self::Mov_R_R { is_64, src, dst } if *is_64 => Some((*dst, *src)),
_ => None,
}
}
fn is_epilogue_placeholder(&self) -> bool {
if let Self::EpiloguePlaceholder = self {
true
} else {
false
}
}
fn is_term<'a>(&'a self) -> MachTerminator<'a> {
match self {
// Interesting cases.
&Self::Ret | &Self::EpiloguePlaceholder => MachTerminator::Ret,
&Self::JmpKnown { dest } => MachTerminator::Uncond(dest.as_label().unwrap()),
&Self::JmpCondSymm {
cc: _,
taken,
not_taken,
} => MachTerminator::Cond(taken.as_label().unwrap(), not_taken.as_label().unwrap()),
// All other cases are boring.
_ => MachTerminator::None,
}
}
fn gen_move(dst_reg: Writable<Reg>, src_reg: Reg, _ty: Type) -> Inst {
let rc_dst = dst_reg.to_reg().get_class();
let rc_src = src_reg.get_class();
// If this isn't true, we have gone way off the rails.
debug_assert!(rc_dst == rc_src);
match rc_dst {
RegClass::I64 => Inst::mov_r_r(true, src_reg, dst_reg),
_ => panic!("gen_move(x64): unhandled regclass"),
}
}
fn gen_zero_len_nop() -> Inst {
unimplemented!()
}
fn gen_nop(_preferred_size: usize) -> Inst {
unimplemented!()
}
fn maybe_direct_reload(&self, _reg: VirtualReg, _slot: SpillSlot) -> Option<Inst> {
None
}
fn rc_for_type(ty: Type) -> CodegenResult<RegClass> {
match ty {
I8 | I16 | I32 | I64 | B1 | B8 | B16 | B32 | B64 => Ok(RegClass::I64),
F32 | F64 | I128 | B128 => Ok(RegClass::V128),
_ => Err(CodegenError::Unsupported(format!(
"Unexpected SSA-value type: {}",
ty
))),
}
}
fn gen_jump(label: MachLabel) -> Inst {
Inst::jmp_known(BranchTarget::Label(label))
}
fn gen_constant(to_reg: Writable<Reg>, value: u64, _: Type) -> SmallVec<[Self; 4]> {
let mut ret = SmallVec::new();
let is64 = value > 0xffff_ffff;
ret.push(Inst::imm_r(is64, value, to_reg));
ret
}
fn reg_universe(flags: &Flags) -> RealRegUniverse {
create_reg_universe_systemv(flags)
}
fn worst_case_size() -> CodeOffset {
15
}
type LabelUse = LabelUse;
}
impl MachInstEmit for Inst {
type State = ();
fn emit(&self, sink: &mut MachBuffer<Inst>, _flags: &settings::Flags, _: &mut Self::State) {
emit::emit(self, sink);
}
}
/// A label-use (internal relocation) in generated code.
#[derive(Clone, Copy, Debug, PartialEq, Eq)]
pub(crate) enum LabelUse {
/// A 32-bit offset from location of relocation itself, added to the
/// existing value at that location.
Rel32,
}
impl MachInstLabelUse for LabelUse {
const ALIGN: CodeOffset = 1;
fn max_pos_range(self) -> CodeOffset {
match self {
LabelUse::Rel32 => 0x7fff_ffff,
}
}
fn max_neg_range(self) -> CodeOffset {
match self {
LabelUse::Rel32 => 0x8000_0000,
}
}
fn patch_size(self) -> CodeOffset {
match self {
LabelUse::Rel32 => 4,
}
}
fn patch(self, buffer: &mut [u8], use_offset: CodeOffset, label_offset: CodeOffset) {
match self {
LabelUse::Rel32 => {
let addend = i32::from_le_bytes([buffer[0], buffer[1], buffer[2], buffer[3]]);
let value = i32::try_from(label_offset)
.unwrap()
.wrapping_sub(i32::try_from(use_offset).unwrap())
.wrapping_add(addend);
buffer.copy_from_slice(&value.to_le_bytes()[..]);
}
}
}
fn supports_veneer(self) -> bool {
match self {
LabelUse::Rel32 => false,
}
}
fn veneer_size(self) -> CodeOffset {
match self {
LabelUse::Rel32 => 0,
}
}
fn generate_veneer(self, _: &mut [u8], _: CodeOffset) -> (CodeOffset, LabelUse) {
match self {
LabelUse::Rel32 => {
panic!("Veneer not supported for Rel32 label-use.");
}
}
}
}