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Cranelift: Add iconst shorthand to simplify ISLE opts #7670

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merged 4 commits into from
Dec 12, 2023
Merged

Cranelift: Add iconst shorthand to simplify ISLE opts #7670

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5eef224
Demote `simm32` and `uimm8` to lowering ISLE only
scottmcm Dec 9, 2023
dae32c0
Cranelift: Add iconst shorthand to simplify ISLE opts
scottmcm Dec 9, 2023
2481c39
Do a manually un-currying to avoid duplicating loading the `Instructi…
scottmcm Dec 11, 2023
af1f83a
rustfmt is my nemesis
scottmcm Dec 11, 2023
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12 changes: 0 additions & 12 deletions cranelift/codegen/src/isle_prelude.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -734,18 +734,6 @@ macro_rules! isle_common_prelude_methods {
Imm64::new((x & self.ty_mask(ty)) as i64)
}

#[inline]
fn simm32(&mut self, x: Imm64) -> Option<i32> {
i64::from(x).try_into().ok()
}

#[inline]
fn uimm8(&mut self, x: Imm64) -> Option<u8> {
let x64: i64 = x.into();
let x8: u8 = x64.try_into().ok()?;
Some(x8)
}

#[inline]
fn offset32(&mut self, x: Offset32) -> i32 {
x.into()
Expand Down
12 changes: 12 additions & 0 deletions cranelift/codegen/src/machinst/isle.rs
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Expand Up @@ -562,6 +562,18 @@ macro_rules! isle_lower_prelude_methods {
Some(value)
}

#[inline]
fn simm32(&mut self, x: Imm64) -> Option<i32> {
i64::from(x).try_into().ok()
}

#[inline]
fn uimm8(&mut self, x: Imm64) -> Option<u8> {
let x64: i64 = x.into();
let x8: u8 = x64.try_into().ok()?;
Some(x8)
}

#[inline]
fn preg_to_reg(&mut self, preg: PReg) -> Reg {
preg.into()
Expand Down
24 changes: 24 additions & 0 deletions cranelift/codegen/src/opts.rs
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Expand Up @@ -27,6 +27,8 @@ const MAX_ISLE_RETURNS: usize = 8;

pub type ConstructorVec<T> = SmallVec<[T; MAX_ISLE_RETURNS]>;

type TypeAndInstructionData = (Type, InstructionData);

impl<T: smallvec::Array> generated_code::Length for SmallVec<T> {
#[inline]
fn len(&self) -> usize {
Expand Down Expand Up @@ -128,6 +130,13 @@ impl<'a, 'b, 'c> generated_code::Context for IsleContext<'a, 'b, 'c> {
*returns = InstDataEtorIter::new(eclass);
}

type inst_data_tupled_etor_returns = InstDataEtorIter<'a, 'b, 'c>;

fn inst_data_tupled_etor(&mut self, eclass: Value, returns: &mut InstDataEtorIter<'a, 'b, 'c>) {
// Literally identical to `inst_data_etor`, just a different nominal type in ISLE
self.inst_data_etor(eclass, returns);
}

fn make_inst_ctor(&mut self, ty: Type, op: &InstructionData) -> Value {
let value = self
.ctx
Expand All @@ -149,6 +158,21 @@ impl<'a, 'b, 'c> generated_code::Context for IsleContext<'a, 'b, 'c> {
self.ctx.func.dfg.value_type(val)
}

fn iconst_sextend_etor(
&mut self,
(ty, inst_data): (Type, InstructionData),
) -> Option<(Type, i64)> {
if let InstructionData::UnaryImm {
opcode: Opcode::Iconst,
imm,
} = inst_data
{
Some((ty, self.i64_sextend_imm64(ty, imm)))
} else {
None
}
}

fn remat(&mut self, value: Value) -> Value {
trace!("remat: {}", value);
self.ctx.remat_values.insert(value);
Expand Down
28 changes: 13 additions & 15 deletions cranelift/codegen/src/opts/arithmetic.isle
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Original file line number Diff line number Diff line change
Expand Up @@ -7,16 +7,16 @@
;; x+0 == x.
(rule (simplify (iadd ty
x
(iconst ty (u64_from_imm64 0))))
(iconst_u ty 0)))
(subsume x))
;; x-0 == x.
(rule (simplify (isub ty
x
(iconst ty (u64_from_imm64 0))))
(iconst_u ty 0)))
(subsume x))
;; 0-x == (ineg x).
(rule (simplify (isub ty
(iconst ty (u64_from_imm64 0))
(iconst_u ty 0)
x))
(ineg ty x))

Expand Down Expand Up @@ -47,51 +47,49 @@
(subsume inner))

;; x-x == 0.
(rule (simplify (isub (fits_in_64 (ty_int ty)) x x)) (subsume (iconst ty (imm64 0))))
(rule (simplify (isub (fits_in_64 (ty_int ty)) x x)) (subsume (iconst_u ty 0)))

;; x*1 == x.
(rule (simplify (imul ty
x
(iconst ty (u64_from_imm64 1))))
(iconst_u ty 1)))
(subsume x))

;; x*0 == 0.
(rule (simplify (imul ty
_
zero @ (iconst ty (u64_from_imm64 0))))
zero @ (iconst_u ty 0)))
(subsume zero))

;; x*-1 == ineg(x).
(rule (simplify (imul ty x (iconst ty c)))
(if-let -1 (i64_sextend_imm64 ty c))
(rule (simplify (imul ty x (iconst_s ty -1)))
(ineg ty x))

;; (!x) + 1 == ineg(x)
(rule (simplify (iadd ty (bnot ty x) (iconst ty (u64_from_imm64 1))))
(rule (simplify (iadd ty (bnot ty x) (iconst_u ty 1)))
(ineg ty x))

;; !(x - 1) == !(x + (-1)) == ineg(x)
(rule (simplify (bnot ty (isub ty x (iconst ty (u64_from_imm64 1)))))
(rule (simplify (bnot ty (isub ty x (iconst_s ty 1))))
(ineg ty x))
(rule (simplify (bnot ty (iadd ty x (iconst ty c))))
(if-let -1 (i64_sextend_imm64 ty c))
(rule (simplify (bnot ty (iadd ty x (iconst_s ty -1))))
(ineg ty x))

;; x/1 == x.
(rule (simplify (sdiv ty
x
(iconst ty (u64_from_imm64 1))))
(iconst_u ty 1)))
(subsume x))
(rule (simplify (udiv ty
x
(iconst ty (u64_from_imm64 1))))
(iconst_u ty 1)))
(subsume x))

;; TODO: strength reduction: div to shifts
;; TODO: div/rem by constants -> magic multiplications

;; x*2 == x+x.
(rule (simplify (imul ty x (iconst _ (simm32 2))))
(rule (simplify (imul ty x (iconst_u _ 2)))
(iadd ty x x))

;; x*c == x<<log2(c) when c is a power of two.
Expand Down
64 changes: 31 additions & 33 deletions cranelift/codegen/src/opts/bitops.isle
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Expand Up @@ -3,20 +3,20 @@
;; x | 0 == x | x == x.
(rule (simplify (bor ty
x
(iconst ty (u64_from_imm64 0))))
(iconst_u ty 0)))
(subsume x))
(rule (simplify (bor ty x x))
(subsume x))

;; x ^ 0 == x.
(rule (simplify (bxor ty
x
(iconst ty (u64_from_imm64 0))))
(iconst_u ty 0)))
(subsume x))

;; x ^ x == 0.
(rule (simplify (bxor (fits_in_64 (ty_int ty)) x x))
(subsume (iconst ty (imm64 0))))
(subsume (iconst_u ty 0)))

;; x ^ not(x) == not(x) ^ x == x | not(x) == not(x) | x == -1.
;; This identity also holds for non-integer types, vectors, and wider types.
Expand All @@ -28,14 +28,13 @@

;; x & x == x & -1 == x.
(rule (simplify (band ty x x)) (subsume x))
(rule (simplify (band ty x (iconst ty k)))
(if-let -1 (i64_sextend_imm64 ty k))
(rule (simplify (band ty x (iconst_s ty -1)))
(subsume x))

;; x & 0 == x & not(x) == not(x) & x == 0.
(rule (simplify (band ty _ zero @ (iconst ty (u64_from_imm64 0)))) (subsume zero))
(rule (simplify (band (fits_in_64 (ty_int ty)) x (bnot ty x))) (subsume (iconst ty (imm64 0))))
(rule (simplify (band (fits_in_64 (ty_int ty)) (bnot ty x) x)) (subsume (iconst ty (imm64 0))))
(rule (simplify (band ty _ zero @ (iconst_u ty 0))) (subsume zero))
(rule (simplify (band (fits_in_64 (ty_int ty)) x (bnot ty x))) (subsume (iconst_u ty 0)))
(rule (simplify (band (fits_in_64 (ty_int ty)) (bnot ty x) x)) (subsume (iconst_u ty 0)))

;; not(not(x)) == x.
(rule (simplify (bnot ty (bnot ty x))) (subsume x))
Expand Down Expand Up @@ -77,8 +76,7 @@
(bor ty x z))

;; (x ^ -1) can be replaced with the `bnot` instruction
(rule (simplify (bxor ty x (iconst ty k)))
(if-let -1 (i64_sextend_imm64 ty k))
(rule (simplify (bxor ty x (iconst_s ty -1)))
(bnot ty x))

;; sshr((x | -x), N) == bmask(x) where N = ty_bits(ty) - 1.
Expand Down Expand Up @@ -108,17 +106,17 @@
(rule (truthy (rotr _ x _)) x)
(rule (truthy (select _ x (iconst _ (u64_from_imm64 (u64_nonzero _))) (iconst _ (u64_from_imm64 0)))) x)
;; (ne ty (iconst 0) v) is also canonicalized into this form via another rule
(rule (truthy (ne _ x (iconst _ (u64_from_imm64 0)))) x)
(rule (truthy (ne _ x (iconst_u _ 0))) x)

;; All of these expressions don't care about their input as long as it is truthy.
;; so we can remove expressions that preserve that property from the input.
(rule (simplify (bmask ty v)) (if-let x (truthy v)) (bmask ty x))
(rule (simplify (select ty v t f)) (if-let c (truthy v)) (select ty c t f))
;; (ne ty (iconst 0) v) is also canonicalized into this form via another rule
(rule (simplify (ne cty v (iconst _ (u64_from_imm64 0))))
(rule (simplify (ne cty v (iconst_u _ 0)))
(if-let c (truthy v))
(if-let (value_type (ty_int_ref_scalar_64 ty)) c)
(ne cty c (iconst ty (imm64 0))))
(ne cty c (iconst_u ty 0)))



Expand All @@ -145,42 +143,42 @@
;; easy way to match all of them, so only one is matched here.
(rule (simplify (bor ty @ $I32
(bor ty
(ishl ty x (iconst ty (u64_from_imm64 24)))
(ishl ty x (iconst_u ty 24))
(ishl ty
(band ty x (iconst ty (u64_from_imm64 0xff00)))
(iconst ty (u64_from_imm64 8))))
(band ty x (iconst_u ty 0xff00))
(iconst_u ty 8)))
(bor ty
(band ty
(ushr ty x (iconst ty (u64_from_imm64 8)))
(iconst ty (u64_from_imm64 0xff00)))
(ushr ty x (iconst ty (u64_from_imm64 24))))))
(ushr ty x (iconst_u ty 8))
(iconst_u ty 0xff00))
(ushr ty x (iconst_u ty 24)))))
(bswap ty x))

(rule (simplify (bor ty @ $I64
(bor ty
(bor ty
(ishl ty x (iconst ty (u64_from_imm64 56)))
(ishl ty x (iconst_u ty 56))
(ishl ty
(band ty x (iconst ty (u64_from_imm64 0xff00)))
(iconst ty (u64_from_imm64 40))))
(band ty x (iconst_u ty 0xff00))
(iconst_u ty 40)))
(bor ty
(ishl ty
(band ty x (iconst ty (u64_from_imm64 0xff_0000)))
(iconst ty (u64_from_imm64 24)))
(band ty x (iconst_u ty 0xff_0000))
(iconst_u ty 24))
(ishl ty
(band ty x (iconst ty (u64_from_imm64 0xff00_0000)))
(iconst ty (u64_from_imm64 8)))))
(band ty x (iconst_u ty 0xff00_0000))
(iconst_u ty 8))))
(bor ty
(bor ty
(band ty
(ushr ty x (iconst ty (u64_from_imm64 8)))
(iconst ty (u64_from_imm64 0xff00_0000)))
(ushr ty x (iconst_u ty 8))
(iconst_u ty 0xff00_0000))
(band ty
(ushr ty x (iconst ty (u64_from_imm64 24)))
(iconst ty (u64_from_imm64 0xff_0000))))
(ushr ty x (iconst_u ty 24))
(iconst_u ty 0xff_0000)))
(bor ty
(band ty
(ushr ty x (iconst ty (u64_from_imm64 40)))
(iconst ty (u64_from_imm64 0xff00)))
(ushr ty x (iconst ty (u64_from_imm64 56)))))))
(ushr ty x (iconst_u ty 40))
(iconst_u ty 0xff00))
(ushr ty x (iconst_u ty 56))))))
(bswap ty x))
20 changes: 10 additions & 10 deletions cranelift/codegen/src/opts/extends.isle
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Expand Up @@ -28,22 +28,22 @@
(rule (simplify
(slt ty
(uextend $I64 x @ (value_type $I32))
(iconst _ (u64_from_imm64 0))))
(iconst ty (imm64 0)))
(iconst_u _ 0)))
(iconst_u ty 0))
(rule (simplify
(sge ty
(uextend $I64 x @ (value_type $I32))
(iconst _ (u64_from_imm64 0))))
(iconst ty (imm64 1)))
(iconst_u _ 0)))
(iconst_u ty 1))

;; Sign-extending can't change whether a number is zero nor how it signed-compares to zero
(rule (simplify (eq _ (sextend _ x@(value_type ty)) (iconst _ (u64_from_imm64 0))))
(eq ty x (iconst ty (imm64 0))))
(rule (simplify (ne _ (sextend _ x@(value_type ty)) (iconst _ (u64_from_imm64 0))))
(ne ty x (iconst ty (imm64 0))))
(rule (simplify (icmp _ cc (sextend _ x@(value_type ty)) (iconst _ (u64_from_imm64 0))))
(rule (simplify (eq _ (sextend _ x@(value_type ty)) (iconst_s _ 0)))
(eq ty x (iconst_s ty 0)))
(rule (simplify (ne _ (sextend _ x@(value_type ty)) (iconst_s _ 0)))
(ne ty x (iconst_s ty 0)))
(rule (simplify (icmp _ cc (sextend _ x@(value_type ty)) (iconst_s _ 0)))
(if (signed_cond_code cc))
(icmp ty cc x (iconst ty (imm64 0))))
(icmp ty cc x (iconst_s ty 0)))

;; A reduction-of-an-extend back to the same original type is the same as not
;; actually doing the extend in the first place.
Expand Down
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