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machinst x64: remove dead code and allow(dead_code) annotation;

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The BranchTarget is always used as a label, so just use a plain
MachLabel in this case.
This commit is contained in:
Benjamin Bouvier
2020-10-07 13:31:29 +02:00
parent e32e6fb612
commit a470f1e0cd
7 changed files with 90 additions and 165 deletions
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109
cranelift/codegen/src/isa/x64/inst/emit.rs
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@@ -7,7 +7,6 @@ use crate::machinst::{inst_common, MachBuffer, MachInstEmit, MachLabel};
use core::convert::TryInto;
use log::debug;
use regalloc::{Reg, RegClass, Writable};
use std::convert::TryFrom;
fn low8_will_sign_extend_to_64(x: u32) -> bool {
let xs = (x as i32) as i64;
@@ -296,18 +295,9 @@ fn emit_std_enc_mem(
// RIP-relative is mod=00, rm=101.
sink.put1(encode_modrm(0, enc_g & 7, 0b101));
match *target {
BranchTarget::Label(label) => {
let offset = sink.cur_offset();
sink.use_label_at_offset(offset, label, LabelUse::JmpRel32);
sink.put4(0);
}
BranchTarget::ResolvedOffset(offset) => {
let offset =
u32::try_from(offset).expect("rip-relative can't hold >= U32_MAX values");
sink.put4(offset);
}
}
let offset = sink.cur_offset();
sink.use_label_at_offset(offset, *target, LabelUse::JmpRel32);
sink.put4(0);
}
}
}
@@ -808,7 +798,7 @@ pub(crate) fn emit(
);
inst.emit(sink, info, state);
let inst = Inst::jmp_known(BranchTarget::Label(done_label));
let inst = Inst::jmp_known(done_label);
inst.emit(sink, info, state);
(Some(do_op), Some(done_label))
@@ -1503,30 +1493,26 @@ pub(crate) fn emit(
let br_start = sink.cur_offset();
let br_disp_off = br_start + 1;
let br_end = br_start + 5;
if let Some(l) = dst.as_label() {
sink.use_label_at_offset(br_disp_off, l, LabelUse::JmpRel32);
sink.add_uncond_branch(br_start, br_end, l);
}
let disp = dst.as_offset32_or_zero();
let disp = disp as u32;
sink.use_label_at_offset(br_disp_off, *dst, LabelUse::JmpRel32);
sink.add_uncond_branch(br_start, br_end, *dst);
sink.put1(0xE9);
sink.put4(disp);
// Placeholder for the label value.
sink.put4(0x0);
}
Inst::JmpIf { cc, taken } => {
let cond_start = sink.cur_offset();
let cond_disp_off = cond_start + 2;
if let Some(l) = taken.as_label() {
sink.use_label_at_offset(cond_disp_off, l, LabelUse::JmpRel32);
// Since this is not a terminator, don't enroll in the branch inversion mechanism.
}
let taken_disp = taken.as_offset32_or_zero();
let taken_disp = taken_disp as u32;
sink.use_label_at_offset(cond_disp_off, *taken, LabelUse::JmpRel32);
// Since this is not a terminator, don't enroll in the branch inversion mechanism.
sink.put1(0x0F);
sink.put1(0x80 + cc.get_enc());
sink.put4(taken_disp);
// Placeholder for the label value.
sink.put4(0x0);
}
Inst::JmpCond {
@@ -1538,32 +1524,27 @@ pub(crate) fn emit(
let cond_start = sink.cur_offset();
let cond_disp_off = cond_start + 2;
let cond_end = cond_start + 6;
if let Some(l) = taken.as_label() {
sink.use_label_at_offset(cond_disp_off, l, LabelUse::JmpRel32);
let inverted: [u8; 6] =
[0x0F, 0x80 + (cc.invert().get_enc()), 0x00, 0x00, 0x00, 0x00];
sink.add_cond_branch(cond_start, cond_end, l, &inverted[..]);
}
let taken_disp = taken.as_offset32_or_zero();
let taken_disp = taken_disp as u32;
sink.use_label_at_offset(cond_disp_off, *taken, LabelUse::JmpRel32);
let inverted: [u8; 6] = [0x0F, 0x80 + (cc.invert().get_enc()), 0x00, 0x00, 0x00, 0x00];
sink.add_cond_branch(cond_start, cond_end, *taken, &inverted[..]);
sink.put1(0x0F);
sink.put1(0x80 + cc.get_enc());
sink.put4(taken_disp);
// Placeholder for the label value.
sink.put4(0x0);
// If not taken.
let uncond_start = sink.cur_offset();
let uncond_disp_off = uncond_start + 1;
let uncond_end = uncond_start + 5;
if let Some(l) = not_taken.as_label() {
sink.use_label_at_offset(uncond_disp_off, l, LabelUse::JmpRel32);
sink.add_uncond_branch(uncond_start, uncond_end, l);
}
let nt_disp = not_taken.as_offset32_or_zero();
let nt_disp = nt_disp as u32;
sink.use_label_at_offset(uncond_disp_off, *not_taken, LabelUse::JmpRel32);
sink.add_uncond_branch(uncond_start, uncond_end, *not_taken);
sink.put1(0xE9);
sink.put4(nt_disp);
// Placeholder for the label value.
sink.put4(0x0);
}
Inst::JmpUnknown { target } => {
@@ -1625,11 +1606,7 @@ pub(crate) fn emit(
// j *%tmp1
// $start_of_jump_table:
// -- jump table entries
let default_label = match default_target {
BranchTarget::Label(label) => label,
_ => unreachable!(),
};
one_way_jmp(sink, CC::NB, *default_label); // idx unsigned >= jmp table size
one_way_jmp(sink, CC::NB, *default_target); // idx unsigned >= jmp table size
// Copy the index (and make sure to clear the high 32-bits lane of tmp2).
let inst = Inst::movzx_rm_r(ExtMode::LQ, RegMem::reg(*idx), *tmp2, None);
@@ -1637,10 +1614,7 @@ pub(crate) fn emit(
// Load base address of jump table.
let start_of_jumptable = sink.get_label();
let inst = Inst::lea(
Amode::rip_relative(BranchTarget::Label(start_of_jumptable)),
*tmp1,
);
let inst = Inst::lea(Amode::rip_relative(start_of_jumptable), *tmp1);
inst.emit(sink, info, state);
// Load value out of the jump table. It's a relative offset to the target block, so it
@@ -1676,7 +1650,7 @@ pub(crate) fn emit(
// with the extra addend, it'll be relative to the jump table's start, after
// patching.
let off_into_table = word_off - jt_off;
sink.use_label_at_offset(word_off, target.as_label().unwrap(), LabelUse::PCRel32);
sink.use_label_at_offset(word_off, target, LabelUse::PCRel32);
sink.put4(off_into_table);
}
}
@@ -1912,7 +1886,7 @@ pub(crate) fn emit(
let inst = Inst::xmm_rm_r(op, RegMem::reg(*lhs), *rhs_dst);
inst.emit(sink, info, state);
let inst = Inst::jmp_known(BranchTarget::Label(done));
let inst = Inst::jmp_known(done);
inst.emit(sink, info, state);
// x86's min/max are not symmetric; if either operand is a NaN, they return the
@@ -1994,14 +1968,13 @@ pub(crate) fn emit(
// Load the inline constant.
let constant_start_label = sink.get_label();
let load_offset = Amode::rip_relative(BranchTarget::Label(constant_start_label));
let load_offset = Amode::rip_relative(constant_start_label);
let load = Inst::load(*ty, load_offset, *dst, ExtKind::None, None);
load.emit(sink, info, state);
// Jump over the constant.
let constant_end_label = sink.get_label();
let continue_at_offset = BranchTarget::Label(constant_end_label);
let jump = Inst::jmp_known(continue_at_offset);
let jump = Inst::jmp_known(constant_end_label);
jump.emit(sink, info, state);
// Emit the constant.
@@ -2169,7 +2142,7 @@ pub(crate) fn emit(
// right thing.
emit_signed_cvt(sink, info, state, src.to_reg(), *dst, *to_f64);
let inst = Inst::jmp_known(BranchTarget::Label(done));
let inst = Inst::jmp_known(done);
inst.emit(sink, info, state);
sink.bind_label(handle_negative);
@@ -2308,7 +2281,7 @@ pub(crate) fn emit(
);
inst.emit(sink, info, state);
let inst = Inst::jmp_known(BranchTarget::Label(done));
let inst = Inst::jmp_known(done);
inst.emit(sink, info, state);
sink.bind_label(not_nan);
@@ -2499,7 +2472,7 @@ pub(crate) fn emit(
);
inst.emit(sink, info, state);
let inst = Inst::jmp_known(BranchTarget::Label(done));
let inst = Inst::jmp_known(done);
inst.emit(sink, info, state);
} else {
// Trap.
@@ -2531,7 +2504,7 @@ pub(crate) fn emit(
);
inst.emit(sink, info, state);
let inst = Inst::jmp_known(BranchTarget::Label(done));
let inst = Inst::jmp_known(done);
inst.emit(sink, info, state);
} else {
// Trap.
@@ -2569,7 +2542,7 @@ pub(crate) fn emit(
);
inst.emit(sink, info, state);
let inst = Inst::jmp_known(BranchTarget::Label(done));
let inst = Inst::jmp_known(done);
inst.emit(sink, info, state);
} else {
let inst = Inst::trap(*srcloc, TrapCode::IntegerOverflow);
@@ -2746,7 +2719,15 @@ pub(crate) fn emit(
state.virtual_sp_offset += offset;
}
Inst::Nop { .. } | Inst::EpiloguePlaceholder => {
Inst::Nop { len } => {
if *len == 0 {
// Nothing to emit.
} else {
unimplemented!("non-zero nop opcodes.");
}
}
Inst::EpiloguePlaceholder => {
// Generate no code.
}
}