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x64: clean up regalloc-related semantics on several instructions. (#4811)

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* x64: clean up regalloc-related semantics on several instructions.

This PR removes all uses of "modify" operands on instructions in the x64
backend, and also removes all uses of "pinned vregs", or vregs that are
explicitly tied to particular physical registers. In place of both of
these mechanisms, which are legacies of the old regalloc design and
supported via compatibility code, the backend now uses operand
constraints. This is more flexible as it allows the regalloc to see the
liveranges and constraints without "reverse-engineering" move instructions.

Eventually, after removing all such uses (including in other backends
and by the ABI code), we can remove the compatibility code in regalloc2,
significantly simplifying its liverange-construction frontend and
thus allowing for higher confidence in correctness as well as possibly a
bit more compilation speed.

Curiously, there are a few extra move instructions now; they are likely
poor splitting decisions and I can try to chase these down later.

* Fix cranelift-codegen tests.

* Review feedback.
This commit is contained in:
Chris Fallin
2022-08-30 17:21:14 -07:00
committed by GitHub
parent 3ce3eeb668
commit 186c7c3b89
14 changed files with 543 additions and 284 deletions
Download Patch File Download Diff File Expand all files Collapse all files

149
cranelift/codegen/src/isa/x64/inst/mod.rs
View File

@@ -131,7 +131,9 @@ impl Inst {
| Inst::XmmToGpr { op, .. }
| Inst::XmmUnaryRmR { op, .. } => smallvec![op.available_from()],
Inst::XmmUnaryRmREvex { op, .. } | Inst::XmmRmREvex { op, .. } => op.available_from(),
Inst::XmmUnaryRmREvex { op, .. }
| Inst::XmmRmREvex { op, .. }
| Inst::XmmRmREvex3 { op, .. } => op.available_from(),
Inst::XmmRmRVex { op, .. } => op.available_from(),
}
@@ -195,47 +197,55 @@ impl Inst {
}
}
pub(crate) fn div(size: OperandSize, signed: bool, divisor: RegMem) -> Inst {
pub(crate) fn div(
size: OperandSize,
signed: bool,
divisor: RegMem,
dividend_lo: Gpr,
dividend_hi: Gpr,
dst_quotient: WritableGpr,
dst_remainder: WritableGpr,
) -> Inst {
divisor.assert_regclass_is(RegClass::Int);
Inst::Div {
size,
signed,
divisor: GprMem::new(divisor).unwrap(),
dividend_lo: Gpr::new(regs::rax()).unwrap(),
dividend_hi: Gpr::new(regs::rdx()).unwrap(),
dst_quotient: WritableGpr::from_reg(Gpr::new(regs::rax()).unwrap()),
dst_remainder: Writable::from_reg(Gpr::new(regs::rdx()).unwrap()),
dividend_lo,
dividend_hi,
dst_quotient,
dst_remainder,
}
}
pub(crate) fn checked_div_or_rem_seq(
kind: DivOrRemKind,
size: OperandSize,
divisor: Writable<Reg>,
divisor: Reg,
dividend_lo: Gpr,
dividend_hi: Gpr,
dst_quotient: WritableGpr,
dst_remainder: WritableGpr,
tmp: Option<Writable<Reg>>,
) -> Inst {
debug_assert!(divisor.to_reg().class() == RegClass::Int);
debug_assert!(divisor.class() == RegClass::Int);
debug_assert!(tmp
.map(|tmp| tmp.to_reg().class() == RegClass::Int)
.unwrap_or(true));
Inst::CheckedDivOrRemSeq {
kind,
size,
divisor: WritableGpr::from_writable_reg(divisor).unwrap(),
dividend_lo: Gpr::new(regs::rax()).unwrap(),
dividend_hi: Gpr::new(regs::rdx()).unwrap(),
dst_quotient: Writable::from_reg(Gpr::new(regs::rax()).unwrap()),
dst_remainder: Writable::from_reg(Gpr::new(regs::rdx()).unwrap()),
divisor: Gpr::new(divisor).unwrap(),
dividend_lo,
dividend_hi,
dst_quotient,
dst_remainder,
tmp: tmp.map(|tmp| WritableGpr::from_writable_reg(tmp).unwrap()),
}
}
pub(crate) fn sign_extend_data(size: OperandSize) -> Inst {
Inst::SignExtendData {
size,
src: Gpr::new(regs::rax()).unwrap(),
dst: Writable::from_reg(Gpr::new(regs::rdx()).unwrap()),
}
pub(crate) fn sign_extend_data(size: OperandSize, src: Gpr, dst: WritableGpr) -> Inst {
Inst::SignExtendData { size, src, dst }
}
pub(crate) fn imm(dst_size: OperandSize, simm64: u64, dst: Writable<Reg>) -> Inst {
@@ -415,24 +425,18 @@ impl Inst {
pub(crate) fn shift_r(
size: OperandSize,
kind: ShiftKind,
num_bits: Option<u8>,
num_bits: Imm8Gpr,
dst: Writable<Reg>,
) -> Inst {
debug_assert!(if let Some(num_bits) = num_bits {
num_bits < size.to_bits()
} else {
true
});
if let Imm8Reg::Imm8 { imm: num_bits } = num_bits.clone().to_imm8_reg() {
debug_assert!(num_bits < size.to_bits());
}
debug_assert!(dst.to_reg().class() == RegClass::Int);
Inst::ShiftR {
size,
kind,
src: Gpr::new(dst.to_reg()).unwrap(),
num_bits: Imm8Gpr::new(match num_bits {
Some(imm) => Imm8Reg::Imm8 { imm },
None => Imm8Reg::Reg { reg: regs::rcx() },
})
.unwrap(),
num_bits,
dst: WritableGpr::from_writable_reg(dst).unwrap(),
}
}
@@ -781,8 +785,11 @@ impl PrettyPrint for Inst {
let dividend_lo = pretty_print_reg(dividend_lo.to_reg(), size.to_bytes(), allocs);
let dst_quotient =
pretty_print_reg(dst_quotient.to_reg().to_reg(), size.to_bytes(), allocs);
let dst_remainder =
pretty_print_reg(dst_remainder.to_reg().to_reg(), size.to_bytes(), allocs);
let dst_remainder = if size.to_bits() > 8 {
pretty_print_reg(dst_remainder.to_reg().to_reg(), size.to_bytes(), allocs)
} else {
"(none)".to_string()
};
let dividend_hi = if size.to_bits() > 8 {
pretty_print_reg(dividend_hi.to_reg(), size.to_bytes(), allocs)
} else {
@@ -842,7 +849,7 @@ impl PrettyPrint for Inst {
} => {
let dividend_lo = pretty_print_reg(dividend_lo.to_reg(), size.to_bytes(), allocs);
let dividend_hi = pretty_print_reg(dividend_hi.to_reg(), size.to_bytes(), allocs);
let divisor = pretty_print_reg(divisor.to_reg().to_reg(), size.to_bytes(), allocs);
let divisor = pretty_print_reg(divisor.to_reg(), size.to_bytes(), allocs);
let dst_quotient =
pretty_print_reg(dst_quotient.to_reg().to_reg(), size.to_bytes(), allocs);
let dst_remainder =
@@ -949,12 +956,34 @@ impl PrettyPrint for Inst {
dst,
..
} => {
let src2 = pretty_print_reg(src2.to_reg(), 8, allocs);
let dst = pretty_print_reg(dst.to_reg().to_reg(), 8, allocs);
let src2 = pretty_print_reg(src2.to_reg(), 8, allocs);
let src1 = src1.pretty_print(8, allocs);
format!("{} {}, {}, {}", ljustify(op.to_string()), src1, src2, dst)
}
Inst::XmmRmREvex3 {
op,
src1,
src2,
src3,
dst,
..
} => {
let dst = pretty_print_reg(dst.to_reg().to_reg(), 8, allocs);
let src2 = pretty_print_reg(src2.to_reg(), 8, allocs);
let src3 = pretty_print_reg(src3.to_reg(), 8, allocs);
let src1 = src1.pretty_print(8, allocs);
format!(
"{} {}, {}, {}, {}",
ljustify(op.to_string()),
src1,
src2,
src3,
dst
)
}
Inst::XmmMinMaxSeq {
lhs,
rhs,
@@ -1084,7 +1113,7 @@ impl PrettyPrint for Inst {
tmp_gpr2,
..
} => {
let src = pretty_print_reg(src.to_reg().to_reg(), 8, allocs);
let src = pretty_print_reg(src.to_reg(), 8, allocs);
let dst = pretty_print_reg(dst.to_reg().to_reg(), dst_size.to_bytes(), allocs);
let tmp_gpr1 = pretty_print_reg(tmp_gpr1.to_reg().to_reg(), 8, allocs);
let tmp_gpr2 = pretty_print_reg(tmp_gpr2.to_reg().to_reg(), 8, allocs);
@@ -1114,7 +1143,7 @@ impl PrettyPrint for Inst {
tmp_gpr,
is_saturating,
} => {
let src = pretty_print_reg(src.to_reg().to_reg(), src_size.to_bytes(), allocs);
let src = pretty_print_reg(src.to_reg(), src_size.to_bytes(), allocs);
let dst = pretty_print_reg(dst.to_reg().to_reg(), dst_size.to_bytes(), allocs);
let tmp_gpr = pretty_print_reg(tmp_gpr.to_reg().to_reg(), 8, allocs);
let tmp_xmm = pretty_print_reg(tmp_xmm.to_reg().to_reg(), 8, allocs);
@@ -1142,7 +1171,7 @@ impl PrettyPrint for Inst {
tmp_xmm,
is_saturating,
} => {
let src = pretty_print_reg(src.to_reg().to_reg(), src_size.to_bytes(), allocs);
let src = pretty_print_reg(src.to_reg(), src_size.to_bytes(), allocs);
let dst = pretty_print_reg(dst.to_reg().to_reg(), dst_size.to_bytes(), allocs);
let tmp_gpr = pretty_print_reg(tmp_gpr.to_reg().to_reg(), 8, allocs);
let tmp_xmm = pretty_print_reg(tmp_xmm.to_reg().to_reg(), 8, allocs);
@@ -1424,9 +1453,19 @@ impl PrettyPrint for Inst {
not_taken.to_string()
),
Inst::JmpTableSeq { idx, .. } => {
Inst::JmpTableSeq {
idx, tmp1, tmp2, ..
} => {
let idx = pretty_print_reg(*idx, 8, allocs);
format!("{} {}", ljustify("br_table".into()), idx)
let tmp1 = pretty_print_reg(tmp1.to_reg(), 8, allocs);
let tmp2 = pretty_print_reg(tmp2.to_reg(), 8, allocs);
format!(
"{} {}, {}, {}",
ljustify("br_table".into()),
idx,
tmp1,
tmp2
)
}
Inst::JmpUnknown { target } => {
@@ -1605,8 +1644,8 @@ fn x64_get_operands<F: Fn(VReg) -> VReg>(inst: &Inst, collector: &mut OperandCol
} => {
collector.reg_fixed_use(dividend_lo.to_reg(), regs::rax());
collector.reg_fixed_def(dst_quotient.to_writable_reg(), regs::rax());
collector.reg_fixed_def(dst_remainder.to_writable_reg(), regs::rdx());
if size.to_bits() > 8 {
collector.reg_fixed_def(dst_remainder.to_writable_reg(), regs::rdx());
collector.reg_fixed_use(dividend_hi.to_reg(), regs::rdx());
}
divisor.get_operands(collector);
@@ -1634,10 +1673,12 @@ fn x64_get_operands<F: Fn(VReg) -> VReg>(inst: &Inst, collector: &mut OperandCol
} => {
collector.reg_fixed_use(dividend_lo.to_reg(), regs::rax());
collector.reg_fixed_use(dividend_hi.to_reg(), regs::rdx());
collector.reg_mod(divisor.to_writable_reg());
collector.reg_use(divisor.to_reg());
collector.reg_fixed_def(dst_quotient.to_writable_reg(), regs::rax());
collector.reg_fixed_def(dst_remainder.to_writable_reg(), regs::rdx());
if let Some(tmp) = tmp {
// Early def so that the temporary register does not
// conflict with inputs or outputs.
collector.reg_early_def(tmp.to_writable_reg());
}
}
@@ -1718,13 +1759,25 @@ fn x64_get_operands<F: Fn(VReg) -> VReg>(inst: &Inst, collector: &mut OperandCol
dst,
..
} => {
match *op {
Avx512Opcode::Vpermi2b => collector.reg_mod(dst.to_writable_reg()),
_ => collector.reg_def(dst.to_writable_reg()),
}
assert_ne!(*op, Avx512Opcode::Vpermi2b);
collector.reg_def(dst.to_writable_reg());
collector.reg_use(src2.to_reg());
src1.get_operands(collector);
}
Inst::XmmRmREvex3 {
op,
src1,
src2,
src3,
dst,
..
} => {
assert_eq!(*op, Avx512Opcode::Vpermi2b);
collector.reg_reuse_def(dst.to_writable_reg(), 2); // Reuse `src3`.
collector.reg_use(src2.to_reg());
collector.reg_use(src3.to_reg());
src1.get_operands(collector);
}
Inst::XmmRmRImm {
op,
src1,
@@ -1795,7 +1848,7 @@ fn x64_get_operands<F: Fn(VReg) -> VReg>(inst: &Inst, collector: &mut OperandCol
tmp_gpr2,
..
} => {
collector.reg_mod(src.to_writable_reg());
collector.reg_use(src.to_reg());
collector.reg_def(dst.to_writable_reg());
collector.reg_early_def(tmp_gpr1.to_writable_reg());
collector.reg_early_def(tmp_gpr2.to_writable_reg());
@@ -1814,7 +1867,7 @@ fn x64_get_operands<F: Fn(VReg) -> VReg>(inst: &Inst, collector: &mut OperandCol
tmp_xmm,
..
} => {
collector.reg_mod(src.to_writable_reg());
collector.reg_use(src.to_reg());
collector.reg_def(dst.to_writable_reg());
collector.reg_early_def(tmp_gpr.to_writable_reg());
collector.reg_early_def(tmp_xmm.to_writable_reg());
@@ -1911,7 +1964,7 @@ fn x64_get_operands<F: Fn(VReg) -> VReg>(inst: &Inst, collector: &mut OperandCol
..
} => {
collector.reg_use(*idx);
collector.reg_mod(*tmp1);
collector.reg_early_def(*tmp1);
collector.reg_early_def(*tmp2);
}