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Fix some 16- and 8-bit behavior in x64 backend related to rotates.

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Uncovered by @bjorn3 (thanks!): 8- and 16-bit rotates were not working
properly in recent versions of Cranelift with part of the lowering
migrated to ISLE.

This PR fixes a few issues:

- 8- and 16-bit rotate-left needs to mask a constant amount, if any,
  because we use a 32-bit rotate instruction and so don't get the
  appropriate shift-amount masking for free from x86 semantics.

- `operand_size_from_type` was incorrect: it only handled 32- and 64-bit
  types and silently returned `OperandSize::Size32` for everything else.
  Now uses the `OperandSize::from_ty(ty)` helper as the pre-ISLE code
  did.

Our test coverage for narrow value types is not great; this PR adds some
runtests for rotl/rotr but more would always be better!
This commit is contained in:
Chris Fallin
2021-12-16 11:34:24 -08:00
parent d29b7c8a59
commit 1323ae417e
10 changed files with 352 additions and 229 deletions
Download Patch File Download Diff File Expand all files Collapse all files

2
cranelift/codegen/src/isa/aarch64/lower/isle/generated_code.manifest
View File

@@ -1,4 +1,4 @@
src/clif.isle be1359b4b6b153f378517c1dd95cd80f4a6bed0c7b86eaba11c088fd71b7bfe80a3c868ace245b2da0bfbbd6ded262ea9576c8e0eeacbf89d03c34a17a709602
src/prelude.isle d3d2a6a42fb778231a4cdca30995324e1293a9ca8073c5a27a501535759eb51f84a6718322a93dfba4b66ee4f0c9afce7dcec0428516ef0c5bc96e8c8b76925d
src/prelude.isle 75a46b97817ad6a4c34e618b81e60876eec6fd1c83ac3ee174851e42045c951644663b2cbc31f1749ce2bc3ad9eb94fb0b877eb2c3bc4885cab7d7e87e9df1d6
src/isa/aarch64/inst.isle 8e4b8e452cf06a368c2e1d930042027a5d3bd690ab46d498d959257e9b4461d17abf244838395cd80da1fe5e2e86fc43855fb5753ca4f1643538c2ae4b3b4a1e
src/isa/aarch64/lower.isle bc3db9c1e6ac186b918cc04f4d26af398f99ec36c8cdc20ec4d02d18dd57dba12e3184fea031b4ac97051c5e194a69666afb5e204807c818e6688c177f9c1b91

13
cranelift/codegen/src/isa/aarch64/lower/isle/generated_code.rs generated
View File

@@ -34,6 +34,8 @@ pub trait Context {
fn ty_bits_u16(&mut self, arg0: Type) -> u16;
fn fits_in_32(&mut self, arg0: Type) -> Option<Type>;
fn fits_in_64(&mut self, arg0: Type) -> Option<Type>;
fn ty_32_or_64(&mut self, arg0: Type) -> Option<Type>;
fn ty_8_or_16(&mut self, arg0: Type) -> Option<Type>;
fn vec128(&mut self, arg0: Type) -> Option<Type>;
fn not_i64x2(&mut self, arg0: Type) -> Option<()>;
fn value_list_slice(&mut self, arg0: ValueList) -> ValueSlice;
@@ -49,6 +51,7 @@ pub trait Context {
fn first_result(&mut self, arg0: Inst) -> Option<Value>;
fn inst_data(&mut self, arg0: Inst) -> InstructionData;
fn value_type(&mut self, arg0: Value) -> Type;
fn ty_bits_mask(&mut self, arg0: Type) -> u64;
fn multi_lane(&mut self, arg0: Type) -> Option<(u8, u16)>;
fn def_inst(&mut self, arg0: Value) -> Option<Inst>;
fn trap_code_division_by_zero(&mut self) -> TrapCode;
@@ -79,13 +82,13 @@ pub trait Context {
fn safe_divisor_from_imm64(&mut self, arg0: Imm64) -> Option<u64>;
}
/// Internal type ProducesFlags: defined at src/prelude.isle line 246.
/// Internal type ProducesFlags: defined at src/prelude.isle line 259.
#[derive(Clone, Debug)]
pub enum ProducesFlags {
ProducesFlags { inst: MInst, result: Reg },
}
/// Internal type ConsumesFlags: defined at src/prelude.isle line 249.
/// Internal type ConsumesFlags: defined at src/prelude.isle line 262.
#[derive(Clone, Debug)]
pub enum ConsumesFlags {
ConsumesFlags { inst: MInst, result: Reg },
@@ -999,7 +1002,7 @@ pub fn constructor_with_flags<C: Context>(
result: pattern3_1,
} = pattern2_0
{
// Rule at src/prelude.isle line 259.
// Rule at src/prelude.isle line 272.
let expr0_0 = C::emit(ctx, &pattern1_0);
let expr1_0 = C::emit(ctx, &pattern3_0);
let expr2_0 = C::value_regs(ctx, pattern1_1, pattern3_1);
@@ -1027,7 +1030,7 @@ pub fn constructor_with_flags_1<C: Context>(
result: pattern3_1,
} = pattern2_0
{
// Rule at src/prelude.isle line 267.
// Rule at src/prelude.isle line 280.
let expr0_0 = C::emit(ctx, &pattern1_0);
let expr1_0 = C::emit(ctx, &pattern3_0);
return Some(pattern3_1);
@@ -1061,7 +1064,7 @@ pub fn constructor_with_flags_2<C: Context>(
result: pattern5_1,
} = pattern4_0
{
// Rule at src/prelude.isle line 277.
// Rule at src/prelude.isle line 290.
let expr0_0 = C::emit(ctx, &pattern1_0);
let expr1_0 = C::emit(ctx, &pattern3_0);
let expr2_0 = C::emit(ctx, &pattern5_0);

4
cranelift/codegen/src/isa/x64/inst.isle
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@@ -379,6 +379,10 @@
(decl imm8_from_value (Imm8Reg) Value)
(extern extractor imm8_from_value imm8_from_value)
;; Mask an `Imm8Reg.Imm8`.
(decl mask_imm8_const (Imm8Reg u64) Imm8Reg)
(extern constructor mask_imm8_const mask_imm8_const)
;; Extract a constant `RegMemImm.Imm` from a value operand.
(decl simm32_from_value (RegMemImm) Value)
(extern extractor simm32_from_value simm32_from_value)

17
cranelift/codegen/src/isa/x64/lower.isle
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@@ -633,15 +633,26 @@
;;;; Rules for `rotl` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; `i64` and smaller.
;; `i16` and `i8`: we need to extend the shift amount, or mask the
;; constant.
(rule (lower (has_type (fits_in_64 ty) (rotl src amt)))
(rule (lower (has_type (ty_8_or_16 ty) (rotl src amt)))
(let ((amt_ Reg (extend_to_reg amt $I32 (ExtendKind.Zero))))
(value_reg (m_rotl ty (put_in_reg src) (Imm8Reg.Reg amt_)))))
(rule (lower (has_type (ty_8_or_16 ty) (rotl src (imm8_from_value amt))))
(value_reg (m_rotl ty (put_in_reg src) (mask_imm8_const amt (ty_bits_mask ty)))))
;; `i64` and `i32`: we can rely on x86's rotate-amount masking since
;; we operate on the whole register.
(rule (lower (has_type (ty_32_or_64 ty) (rotl src amt)))
;; NB: Only the low bits of `amt` matter since we logically mask the
;; shift amount to the value's bit width.
(let ((amt_ Reg (lo_reg amt)))
(value_reg (m_rotl ty (put_in_reg src) (Imm8Reg.Reg amt_)))))
(rule (lower (has_type (fits_in_64 ty) (rotl src (imm8_from_value amt))))
(rule (lower (has_type (ty_32_or_64 ty) (rotl src (imm8_from_value amt))))
(value_reg (m_rotl ty (put_in_reg src) amt)))
;; `i128`.

16
cranelift/codegen/src/isa/x64/lower/isle.rs
View File

@@ -57,11 +57,7 @@ where
#[inline]
fn operand_size_of_type(&mut self, ty: Type) -> OperandSize {
if ty.bits() == 64 {
OperandSize::Size64
} else {
OperandSize::Size32
}
OperandSize::from_ty(ty)
}
fn put_in_reg_mem(&mut self, val: Value) -> RegMem {
@@ -125,6 +121,16 @@ where
Some(Imm8Reg::Imm8 { imm })
}
#[inline]
fn mask_imm8_const(&mut self, imm8: &Imm8Reg, mask: u64) -> Imm8Reg {
match imm8 {
&Imm8Reg::Reg { reg } => Imm8Reg::Reg { reg },
&Imm8Reg::Imm8 { imm } => Imm8Reg::Imm8 {
imm: imm & (mask as u8),
},
}
}
#[inline]
fn simm32_from_value(&mut self, val: Value) -> Option<RegMemImm> {
let inst = self.lower_ctx.dfg().value_def(val).inst()?;

6
cranelift/codegen/src/isa/x64/lower/isle/generated_code.manifest
View File

@@ -1,4 +1,4 @@
src/clif.isle be1359b4b6b153f378517c1dd95cd80f4a6bed0c7b86eaba11c088fd71b7bfe80a3c868ace245b2da0bfbbd6ded262ea9576c8e0eeacbf89d03c34a17a709602
src/prelude.isle d3d2a6a42fb778231a4cdca30995324e1293a9ca8073c5a27a501535759eb51f84a6718322a93dfba4b66ee4f0c9afce7dcec0428516ef0c5bc96e8c8b76925d
src/isa/x64/inst.isle b151120df3c356ac697122a8557becd8857eb725851506e844edeb85d831d461322a96d280ad84f9a23518e1e4efb607aebc0e249004148675e4cc19e89f0655
src/isa/x64/lower.isle c9b408df0a089fb4f207838973ac775b0f9b56c86f056867c28e6bae317873d3844f74f713f9acd6fed98d3d11a2f9d19d392fe5049169dad33b1fc703b9b766
src/prelude.isle 75a46b97817ad6a4c34e618b81e60876eec6fd1c83ac3ee174851e42045c951644663b2cbc31f1749ce2bc3ad9eb94fb0b877eb2c3bc4885cab7d7e87e9df1d6
src/isa/x64/inst.isle 3b9c5c81e40b4de04169ac10e5b57d8de14dfefb104e565d24a303e6ccf28416acbdf585b1cae5a90c7e37310d7cdc1534054202597a7b8d2181c8eece08c29e
src/isa/x64/lower.isle c7943201b32e9eb9726466e8cc417f7e84c4c4052de31e05ab6e0ad7502a587cf1d7d9835703c4ff5a506390f7a0668741e7f3feaa1edda6396571a425949fc9

465
cranelift/codegen/src/isa/x64/lower/isle/generated_code.rs generated
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File diff suppressed because it is too large Load Diff

23
cranelift/codegen/src/machinst/isle.rs
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@@ -95,6 +95,11 @@ macro_rules! isle_prelude_methods {
ty.bits().try_into().unwrap()
}
#[inline]
fn ty_bits_mask(&mut self, ty: Type) -> u64 {
(1 << (self.ty_bits(ty) as u64)) - 1
}
#[inline]
fn ty_bits_u16(&mut self, ty: Type) -> u16 {
ty.bits()
@@ -118,6 +123,24 @@ macro_rules! isle_prelude_methods {
}
}
#[inline]
fn ty_32_or_64(&mut self, ty: Type) -> Option<Type> {
if ty.bits() == 32 || ty.bits() == 64 {
Some(ty)
} else {
None
}
}
#[inline]
fn ty_8_or_16(&mut self, ty: Type) -> Option<Type> {
if ty.bits() == 8 || ty.bits() == 16 {
Some(ty)
} else {
None
}
}
fn vec128(&mut self, ty: Type) -> Option<Type> {
if ty.is_vector() && ty.bits() == 128 {
Some(ty)

13
cranelift/codegen/src/prelude.isle
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@@ -156,6 +156,14 @@
(decl fits_in_64 (Type) Type)
(extern extractor fits_in_64 fits_in_64)
;; An extractor that maches 32- and 64-bit types only.
(decl ty_32_or_64 (Type) Type)
(extern extractor ty_32_or_64 ty_32_or_64)
;; An extractor that maches 8- and 16-bit types only.
(decl ty_8_or_16 (Type) Type)
(extern extractor ty_8_or_16 ty_8_or_16)
;; An extractor that only matches 128-bit vector types.
(decl vec128 (Type) Type)
(extern extractor vec128 vec128)
@@ -230,6 +238,11 @@
(and (result_type ty)
inst))
;; Return a bitmask that will mask off a count to be within `ty`'s
;; bit-width. Used for shifts/rotates.
(decl ty_bits_mask (Type) u64)
(extern constructor ty_bits_mask ty_bits_mask)
;; Match a multi-lane type, extracting (# bits per lane, # lanes) from the given
;; type. Will only match when there is more than one lane.
(decl multi_lane (u8 u16) Type)

22
cranelift/filetests/filetests/runtests/shifts.clif
View File

@@ -318,3 +318,25 @@ block0(v0: i32, v1: i8):
; run: %sshr_i32_i8(0x40000000, 32) == 0x40000000
; run: %sshr_i32_i8(0x40000000, 33) == 0x20000000
; run: %sshr_i32_i8(0x40000000, 34) == 0x10000000
function %rotl_i8_const_37(i8) -> i8 {
block0(v0: i8):
v1 = iconst.i8 37
v2 = rotl.i8 v0, v1
return v2
}
; run: %rotl_i8_const_37(0x00) == 0x00
; run: %rotl_i8_const_37(0x01) == 0x20
; run: %rotl_i8_const_37(0x12) == 0x42
function %rotr_i8_const_37(i8) -> i8 {
block0(v0: i8):
v1 = iconst.i8 37
v2 = rotr.i8 v0, v1
return v2
}
; run: %rotr_i8_const_37(0x00) == 0x00
; run: %rotr_i8_const_37(0x01) == 0x08
; run: %rotr_i8_const_37(0x12) == 0x90