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Remove IFLAGS/FFLAGS types (#5406)

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All instructions using the CPU flags types (IFLAGS/FFLAGS) were already
removed.  This patch completes the cleanup by removing all remaining
instructions that define values of CPU flags types, as well as the
types themselves.

Specifically, the following features are removed:
- The IFLAGS and FFLAGS types and the SpecialType category.
- Special handling of IFLAGS and FFLAGS in machinst/isle.rs and
  machinst/lower.rs.
- The ifcmp, ifcmp_imm, ffcmp, iadd_ifcin, iadd_ifcout, iadd_ifcarry,
  isub_ifbin, isub_ifbout, and isub_ifborrow instructions.
- The writes_cpu_flags instruction property.
- The flags verifier pass.
- Flags handling in the interpreter.

All of these features are currently unused; no functional change
intended by this patch.

This addresses https://github.com/bytecodealliance/wasmtime/issues/3249.
This commit is contained in:
Ulrich Weigand
2022-12-09 22:42:03 +01:00
committed by GitHub
parent 6e0a029c35
commit e913cf3647
42 changed files with 55 additions and 1119 deletions
Download Patch File Download Diff File Expand all files Collapse all files

8
cranelift/codegen/src/isa/aarch64/inst.isle
View File

@@ -1940,14 +1940,6 @@
(MInst.AluRRR (ALUOp.AddS) (operand_size ty) dst src1 src2)
dst)))
;; Helper for emitting `adds` instructions, setting flags in ambient
;; state. Used only for `iadd_ifcout`.
(decl add_with_flags (Type Reg Reg) Reg)
(rule (add_with_flags ty src1 src2)
(let ((dst WritableReg (temp_writable_reg $I64))
(_ Unit (emit (MInst.AluRRR (ALUOp.AddS) (operand_size ty) dst src1 src2))))
dst))
;; Helper for emitting `adc` instructions.
(decl adc_paired (Type Reg Reg) ConsumesFlags)
(rule (adc_paired ty src1 src2)

3
cranelift/codegen/src/isa/aarch64/inst/mod.rs
View File

@@ -1,7 +1,7 @@
//! This module defines aarch64-specific machine instruction types.
use crate::binemit::{Addend, CodeOffset, Reloc};
use crate::ir::types::{F32, F64, FFLAGS, I128, I16, I32, I64, I8, I8X16, IFLAGS, R32, R64};
use crate::ir::types::{F32, F64, I128, I16, I32, I64, I8, I8X16, R32, R64};
use crate::ir::{types, ExternalName, MemFlags, Opcode, Type};
use crate::isa::CallConv;
use crate::machinst::*;
@@ -1280,7 +1280,6 @@ impl MachInst for Inst {
Ok((&[RegClass::Float], &[I8X16]))
}
_ if ty.is_dynamic_vector() => Ok((&[RegClass::Float], &[I8X16])),
IFLAGS | FFLAGS => Ok((&[RegClass::Int], &[I64])),
_ => Err(CodegenError::Unsupported(format!(
"Unexpected SSA-value type: {}",
ty

30
cranelift/codegen/src/isa/aarch64/lower.isle
View File

@@ -2332,36 +2332,6 @@
(lower_msb Reg (lsr_imm $I64 lower_msb (imm_shift_from_u8 63))))
(add_shift $I64 lower_msb upper_msb (lshl_from_u64 $I64 1))))
;;; Rules for `iadd_ifcout` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; This is a two-output instruction that is needed for the
;; legalizer's explicit heap-check sequence, among possible other
;; uses. Its second output is a flags output only ever meant to
;; check for overflow using the
;; `backend.unsigned_add_overflow_condition()` condition.
;;
;; Note that the CLIF validation will ensure that no flag-setting
;; operation comes between this IaddIfcout and its use (e.g., a
;; Trapif). Thus, we can rely on implicit communication through the
;; processor flags rather than explicitly generating flags into a
;; register. We simply use the variant of the add instruction that
;; sets flags (`adds`) here.
;;
;; Note that the second output (the flags) need not be generated,
;; because flags are never materialized into a register; the only
;; instructions that can use a value of type `iflags` or `fflags`
;; will look directly for the flags-producing instruction (which can
;; always be found, by construction) and merge it.
;;
;; Now handle the iadd as above, except use an AddS opcode that sets
;; flags.
(rule (lower (has_type (ty_int ty)
(iadd_ifcout a b)))
(output_pair
(add_with_flags ty a b)
(invalid_reg)))
;;; Rules for `iadd_cout` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; For values smaller than a register, we do a normal `add` with both arguments

18
cranelift/codegen/src/isa/aarch64/lower_inst.rs
View File

@@ -167,14 +167,6 @@ pub(crate) fn lower_insn_to_regs(
Opcode::Return => implemented_in_isle(ctx),
Opcode::Ifcmp | Opcode::Ffcmp => {
// An Ifcmp/Ffcmp must always be seen as a use of a brif/brff or trueif/trueff
// instruction. This will always be the case as long as the IR uses an Ifcmp/Ffcmp from
// the same block, or a dominating block. In other words, it cannot pass through a BB
// param (phi). The flags pass of the verifier will ensure this.
panic!("Should never reach ifcmp as isel root!");
}
Opcode::Icmp => implemented_in_isle(ctx),
Opcode::Fcmp => implemented_in_isle(ctx),
@@ -253,8 +245,6 @@ pub(crate) fn lower_insn_to_regs(
Opcode::FcvtToUintSat | Opcode::FcvtToSintSat => implemented_in_isle(ctx),
Opcode::IaddIfcout => implemented_in_isle(ctx),
Opcode::UaddOverflowTrap => implemented_in_isle(ctx),
Opcode::IaddCout => implemented_in_isle(ctx),
@@ -267,15 +257,10 @@ pub(crate) fn lower_insn_to_regs(
| Opcode::SremImm
| Opcode::IrsubImm
| Opcode::IaddCin
| Opcode::IaddIfcin
| Opcode::IaddCarry
| Opcode::IaddIfcarry
| Opcode::IsubBin
| Opcode::IsubIfbin
| Opcode::IsubBout
| Opcode::IsubIfbout
| Opcode::IsubBorrow
| Opcode::IsubIfborrow
| Opcode::BandImm
| Opcode::BorImm
| Opcode::BxorImm
@@ -284,8 +269,7 @@ pub(crate) fn lower_insn_to_regs(
| Opcode::IshlImm
| Opcode::UshrImm
| Opcode::SshrImm
| Opcode::IcmpImm
| Opcode::IfcmpImm => {
| Opcode::IcmpImm => {
panic!("ALU+imm and ALU+carry ops should not appear here!");
}

4
cranelift/codegen/src/isa/riscv64/inst.isle
View File

@@ -2037,10 +2037,6 @@
(a2 Reg (alu_rr_imm12 (AluOPRRI.Addi) a (imm12_const 1))))
(gen_select_reg (IntCC.SignedLessThan) r (zero_reg) a2 r)))
(decl output_ifcout (Reg) InstOutput)
(rule (output_ifcout reg)
(output_pair reg (value_regs_invalid)))
(decl gen_trapff (FloatCC Reg Reg Type TrapCode) InstOutput)
(rule
(gen_trapff cc a b ty trap_code)

4
cranelift/codegen/src/isa/riscv64/inst/mod.rs
View File

@@ -6,7 +6,7 @@
use crate::binemit::{Addend, CodeOffset, Reloc};
pub use crate::ir::condcodes::IntCC;
use crate::ir::types::{F32, F64, FFLAGS, I128, I16, I32, I64, I8, IFLAGS, R32, R64};
use crate::ir::types::{F32, F64, I128, I16, I32, I64, I8, R32, R64};
pub use crate::ir::{ExternalName, MemFlags, Opcode, SourceLoc, Type, ValueLabel};
use crate::isa::CallConv;
@@ -778,8 +778,6 @@ impl MachInst for Inst {
F32 => Ok((&[RegClass::Float], &[F32])),
F64 => Ok((&[RegClass::Float], &[F64])),
I128 => Ok((&[RegClass::Int, RegClass::Int], &[I64, I64])),
IFLAGS => Ok((&[RegClass::Int], &[IFLAGS])),
FFLAGS => Ok((&[RegClass::Int], &[FFLAGS])),
_ => Err(CodegenError::Unsupported(format!(
"Unexpected SSA-value type: {}",
ty

13
cranelift/codegen/src/isa/riscv64/lower.isle
View File

@@ -43,11 +43,6 @@
(high Reg (alu_add high_tmp carry)))
(value_regs low high)))
;;; Rules for `iadd_ifcout` ;;;;;;;;;;;;;
(rule
(lower (has_type (fits_in_64 ty) (iadd_ifcout x y)))
(output_ifcout (alu_add x y)))
;;; Rules for `uadd_overflow_trap` ;;;;;;;;;;;;;
(rule
(lower (has_type (fits_in_64 ty) (uadd_overflow_trap x y tc)))
@@ -747,14 +742,6 @@
(rule
(lower (icmp cc x @ (value_type ty) y))
(lower_icmp cc x y ty))
;; special for `iadd_ifcout` first out.
(rule 2
(lower (icmp cc (iadd_ifcout a @ (value_type ty) b) y))
(lower_icmp cc (alu_add a b) y ty))
(rule 1
(lower (icmp cc x (iadd_ifcout a @ (value_type ty) b)))
(lower_icmp cc x (alu_add a b) ty))
(decl gen_fcmp (FloatCC Value Value Type) Reg)
(rule

3
cranelift/codegen/src/isa/s390x/inst/mod.rs
View File

@@ -1244,9 +1244,6 @@ impl MachInst for Inst {
types::F64 => Ok((&[RegClass::Float], &[types::F64])),
types::I128 => Ok((&[RegClass::Float], &[types::I128])),
_ if ty.is_vector() && ty.bits() == 128 => Ok((&[RegClass::Float], &[types::I8X16])),
// FIXME: We don't really have IFLAGS, but need to allow it here
// for now to support the SelectifSpectreGuard instruction.
types::IFLAGS => Ok((&[RegClass::Int], &[types::I64])),
_ => Err(CodegenError::Unsupported(format!(
"Unexpected SSA-value type: {}",
ty

53
cranelift/codegen/src/isa/s390x/lower.isle
View File

@@ -192,47 +192,6 @@
(vec_unpacks_low ty y))))
;;;; Rules for `iadd_ifcout` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; N.B.: the second output of `iadd_ifcout` is meant to be the `iflags` value
;; containing the carry result, but we do not support the `iflags` mechanism.
;; However, the only actual use case is where `iadd_ifcout` feeds into `trapif`,
;; which is implemented by explicitly matching on the flags producer. So we can
;; get away with just using an invalid second output, and the reg-renaming code
;; does the right thing, for now.
(decl output_ifcout (Reg) InstOutput)
(rule (output_ifcout reg)
(output_pair reg (value_regs_invalid)))
;; Add two registers.
(rule 0 (lower (has_type (fits_in_64 ty) (iadd_ifcout x y)))
(output_ifcout (add_logical_reg ty x y)))
;; Add a register and a zero-extended register.
(rule 4 (lower (has_type (fits_in_64 ty) (iadd_ifcout x (zext32_value y))))
(output_ifcout (add_logical_reg_zext32 ty x y)))
(rule 8 (lower (has_type (fits_in_64 ty) (iadd_ifcout (zext32_value x) y)))
(output_ifcout (add_logical_reg_zext32 ty y x)))
;; Add a register and an immediate.
(rule 3 (lower (has_type (fits_in_64 ty) (iadd_ifcout x (u32_from_value y))))
(output_ifcout (add_logical_zimm32 ty x y)))
(rule 7 (lower (has_type (fits_in_64 ty) (iadd_ifcout (u32_from_value x) y)))
(output_ifcout (add_logical_zimm32 ty y x)))
;; Add a register and memory (32/64-bit types).
(rule 2 (lower (has_type (fits_in_64 ty) (iadd_ifcout x (sinkable_load_32_64 y))))
(output_ifcout (add_logical_mem ty x (sink_load y))))
(rule 6 (lower (has_type (fits_in_64 ty) (iadd_ifcout (sinkable_load_32_64 x) y)))
(output_ifcout (add_logical_mem ty y (sink_load x))))
;; Add a register and zero-extended memory.
(rule 1 (lower (has_type (fits_in_64 ty) (iadd_ifcout x (sinkable_uload32 y))))
(output_ifcout (add_logical_mem_zext32 ty x (sink_uload32 y))))
(rule 5 (lower (has_type (fits_in_64 ty) (iadd_ifcout (sinkable_uload32 x) y)))
(output_ifcout (add_logical_mem_zext32 ty y (sink_uload32 x))))
;;;; Rules for `iabs` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; Absolute value of a register.
@@ -3742,14 +3701,12 @@
;;;; Rules for `select_spectre_guard` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; We do not support the `iflags` mechanism on our platform. However, common
;; code will unconditionally emit certain patterns using `iflags` which we
;; need to handle somehow. Note that only those specific patterns are
;; recognized by the code below, other uses will fail to lower.
;; We need to guarantee a conditional move instruction. But on this platform
;; this is already the best way to implement select in general, so the
;; implementation of `select_spectre_guard` is identical to `select`.
(rule (lower (has_type ty (select_spectre_guard
(icmp int_cc x y) val_true val_false)))
(select_bool_reg ty (icmp_val $false int_cc x y)
val_cond val_true val_false)))
(select_bool_reg ty (value_nonzero val_cond)
(put_in_reg val_true) (put_in_reg val_false)))

14
cranelift/codegen/src/isa/s390x/lower.rs
View File

@@ -51,7 +51,6 @@ impl LowerBackend for S390xBackend {
| Opcode::Isplit
| Opcode::Iconcat
| Opcode::Iadd
| Opcode::IaddIfcout
| Opcode::Isub
| Opcode::UaddSat
| Opcode::SaddSat
@@ -177,6 +176,7 @@ impl LowerBackend for S390xBackend {
| Opcode::Trapnz
| Opcode::ResumableTrapnz
| Opcode::Debugtrap
| Opcode::UaddOverflowTrap
| Opcode::Call
| Opcode::CallIndirect
| Opcode::Return
@@ -221,9 +221,6 @@ impl LowerBackend for S390xBackend {
Opcode::GlobalValue => {
panic!("global_value should have been removed by legalization!");
}
Opcode::Ifcmp | Opcode::Ffcmp => {
panic!("Flags opcode should not be encountered.");
}
Opcode::Jump | Opcode::Brz | Opcode::Brnz | Opcode::BrTable => {
panic!("Branch opcode reached non-branch lowering logic!");
}
@@ -235,17 +232,11 @@ impl LowerBackend for S390xBackend {
| Opcode::SremImm
| Opcode::IrsubImm
| Opcode::IaddCin
| Opcode::IaddIfcin
| Opcode::IaddCout
| Opcode::IaddCarry
| Opcode::IaddIfcarry
| Opcode::UaddOverflowTrap
| Opcode::IsubBin
| Opcode::IsubIfbin
| Opcode::IsubBout
| Opcode::IsubIfbout
| Opcode::IsubBorrow
| Opcode::IsubIfborrow
| Opcode::BandImm
| Opcode::BorImm
| Opcode::BxorImm
@@ -254,8 +245,7 @@ impl LowerBackend for S390xBackend {
| Opcode::IshlImm
| Opcode::UshrImm
| Opcode::SshrImm
| Opcode::IcmpImm
| Opcode::IfcmpImm => {
| Opcode::IcmpImm => {
panic!("ALU+imm and ALU+carry ops should not appear here!");
}
}

1
cranelift/codegen/src/isa/x64/inst/mod.rs
View File

@@ -2318,7 +2318,6 @@ impl MachInst for Inst {
assert!(ty.bits() <= 128);
Ok((&[RegClass::Float], &[types::I8X16]))
}
types::IFLAGS | types::FFLAGS => Ok((&[RegClass::Int], &[types::I64])),
_ => Err(CodegenError::Unsupported(format!(
"Unexpected SSA-value type: {}",
ty

46
cranelift/codegen/src/isa/x64/lower.isle
View File

@@ -135,49 +135,6 @@
(uadd_sat x y)))
(x64_paddusw x y))
;;;; Rules for `iadd_ifcout` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; N.B.: the second output of `iadd_ifcout` is meant to be the
;; `iflags` value containing the carry result. However, we plan to
;; replace this with a bool carry flag, and all consumers of `iflags`
;; remain in the handwritten pattern-matching code and explicitly
;; match on the flags producer. So we can get away with just
;; using an invalid second output, and the reg-renaming code does the
;; right thing, for now. For safety, we assert elsewhere that no one
;; actually uses the register assigned to the SSA `iflags`-typed
;; `Value`.
(decl output_ifcout (Reg) InstOutput)
(rule (output_ifcout reg)
(output_pair reg (value_regs_invalid)))
;; Add two registers.
(rule 0 (lower (has_type (fits_in_64 ty)
(iadd_ifcout x y)))
(output_ifcout (x64_add ty x y)))
;; Add a register and an immediate.
(rule 1 (lower (has_type (fits_in_64 ty)
(iadd_ifcout x (simm32_from_value y))))
(output_ifcout (x64_add ty x y)))
(rule 2 (lower (has_type (fits_in_64 ty)
(iadd_ifcout (simm32_from_value x) y)))
(output_ifcout (x64_add ty y x)))
;; Add a register and memory.
(rule 3 (lower (has_type (fits_in_64 ty)
(iadd_ifcout x (sinkable_load y))))
(output_ifcout (x64_add ty x (sink_load_to_gpr_mem_imm y))))
(rule 4 (lower (has_type (fits_in_64 ty)
(iadd_ifcout (sinkable_load x) y)))
(output_ifcout (x64_add ty y (sink_load_to_gpr_mem_imm x))))
;; (No `iadd_ifcout` for `i128`.)
;;;; Rules for `isub` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; `i64` and smaller.
@@ -2180,9 +2137,6 @@
(rule (lower (has_type $I64
(uextend src @ (has_type $I32 (iadd _ _)))))
src)
(rule (lower (has_type $I64
(uextend src @ (has_type $I32 (iadd_ifcout _ _)))))
src)
(rule (lower (has_type $I64
(uextend src @ (has_type $I32 (isub _ _)))))
src)

18
cranelift/codegen/src/isa/x64/lower.rs
View File

@@ -332,7 +332,6 @@ fn lower_insn_to_regs(
| Opcode::Null
| Opcode::Iadd
| Opcode::IaddCout
| Opcode::IaddIfcout
| Opcode::SaddSat
| Opcode::UaddSat
| Opcode::Isub
@@ -360,6 +359,7 @@ fn lower_insn_to_regs(
| Opcode::Ineg
| Opcode::Trap
| Opcode::ResumableTrap
| Opcode::UaddOverflowTrap
| Opcode::Clz
| Opcode::Ctz
| Opcode::Popcnt
@@ -500,13 +500,6 @@ fn lower_insn_to_regs(
unimplemented!("Vector split/concat ops not implemented.");
}
// Opcodes that should be removed by legalization. These should
// eventually be removed if/when we replace in-situ legalization with
// something better.
Opcode::Ifcmp | Opcode::Ffcmp => {
panic!("Should never reach ifcmp/ffcmp as isel root!");
}
Opcode::IaddImm
| Opcode::ImulImm
| Opcode::UdivImm
@@ -515,16 +508,10 @@ fn lower_insn_to_regs(
| Opcode::SremImm
| Opcode::IrsubImm
| Opcode::IaddCin
| Opcode::IaddIfcin
| Opcode::IaddCarry
| Opcode::IaddIfcarry
| Opcode::IsubBin
| Opcode::IsubIfbin
| Opcode::IsubBout
| Opcode::IsubIfbout
| Opcode::IsubBorrow
| Opcode::IsubIfborrow
| Opcode::UaddOverflowTrap
| Opcode::BandImm
| Opcode::BorImm
| Opcode::BxorImm
@@ -533,8 +520,7 @@ fn lower_insn_to_regs(
| Opcode::IshlImm
| Opcode::UshrImm
| Opcode::SshrImm
| Opcode::IcmpImm
| Opcode::IfcmpImm => {
| Opcode::IcmpImm => {
panic!("ALU+imm and ALU+carry ops should not appear here!");
}