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Document helpers and abstract conversion checks
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@dheaton-arm
dheaton-arm committed Aug 24, 2022
1 parent 269240f commit 96da208
Showing 1 changed file with 82 additions and 45 deletions.
127 changes: 82 additions & 45 deletions cranelift/codegen/src/isa/aarch64/inst.isle
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Original file line number Diff line number Diff line change
Expand Up @@ -1408,21 +1408,45 @@
(decl u64_into_imm_logic (Type u64) ImmLogic)
(extern constructor u64_into_imm_logic u64_into_imm_logic)

;; Calculate the minimum floating-point bound for a conversion to floating
;; point from an integer type.
;; Accepts whether the output is signed, the size of the input
;; floating point type in bits, and the size of the output integer type
;; in bits.
(decl min_fp_value (bool u8 u8) Reg)
(extern constructor min_fp_value min_fp_value)

;; Calculate the maximum floating-point bound for a conversion to floating
;; point from an integer type.
;; Accepts whether the output is signed, the size of the input
;; floating point type in bits, and the size of the output integer type
;; in bits.
(decl max_fp_value (bool u8 u8) Reg)
(extern constructor max_fp_value max_fp_value)

;; Calculate the minimum acceptable floating-point value for a conversion to
;; floating point from an integer type.
;; Accepts whether the output is signed, the size of the input
;; floating point type in bits, and the size of the output integer type
;; in bits.
(decl min_fp_value_sat (bool u8 u8) Reg)
(extern constructor min_fp_value_sat min_fp_value_sat)

;; Calculate the maximum acceptable floating-point value for a conversion to
;; floating point from an integer type.
;; Accepts whether the output is signed, the size of the input
;; floating point type in bits, and the size of the output integer type
;; in bits.
(decl max_fp_value_sat (bool u8 u8) Reg)
(extern constructor max_fp_value_sat max_fp_value_sat)

;; Constructs an FPUOpRI.Ushr* given the size in bits of the value (or lane)
;; and the amount to shift by.
(decl fpu_op_ri_ushr (u8 u8) FPUOpRI)
(extern constructor fpu_op_ri_ushr fpu_op_ri_ushr)

;; Constructs an FPUOpRI.Sli* given the size in bits of the value (or lane)
;; and the amount to shift by.
(decl fpu_op_ri_sli (u8 u8) FPUOpRI)
(extern constructor fpu_op_ri_sli fpu_op_ri_sli)

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;; Helpers for generating `MInst.FpuToInt` instructions.

(decl fpu_to_int_nan_check () ConsumesFlags)
(rule (fpu_to_int_nan_check)
(ConsumesFlags.ConsumesFlagsSideEffect
(MInst.TrapIf (cond_br_cond (Cond.Vs))
(trap_code_bad_conversion_to_integer))))

;; Emits the appropriate flag-reading op for an underflow check,
(decl fpu_to_int_nan_check (ScalarSize Reg) Reg)
(rule (fpu_to_int_nan_check size src)
(let ((r ValueRegs
(with_flags (fpu_cmp size src src)
(ConsumesFlags.ConsumesFlagsReturnsReg
(MInst.TrapIf (cond_br_cond (Cond.Vs))
(trap_code_bad_conversion_to_integer))
src))))
(value_regs_get r 0)))

;; Checks that the value is not less than the minimum bound,
;; accepting a boolean (whether the type is signed), input type,
;; and output type.
(decl fpu_to_int_underflow_check (bool Type Type) ConsumesFlags)
(rule (fpu_to_int_underflow_check $true $F32 (fits_in_16 out_ty))
(ConsumesFlags.ConsumesFlagsSideEffect
(MInst.TrapIf (cond_br_cond
(Cond.Le))
(trap_code_integer_overflow))))
(rule (fpu_to_int_underflow_check $true $F64 (fits_in_32 out_ty))
(ConsumesFlags.ConsumesFlagsSideEffect
(MInst.TrapIf (cond_br_cond
(Cond.Le))
(trap_code_integer_overflow))))
(rule -1 (fpu_to_int_underflow_check $true _in_ty _out_ty)
(ConsumesFlags.ConsumesFlagsSideEffect
(MInst.TrapIf (cond_br_cond
(Cond.Lt))
(trap_code_integer_overflow))))
(rule (fpu_to_int_underflow_check $false _in_ty _out_ty)
(ConsumesFlags.ConsumesFlagsSideEffect
(MInst.TrapIf (cond_br_cond
(Cond.Le))
(trap_code_integer_overflow))))

(decl fpu_to_int_overflow_check () ConsumesFlags)
(rule (fpu_to_int_overflow_check)
(ConsumesFlags.ConsumesFlagsSideEffect
(MInst.TrapIf (cond_br_cond
(Cond.Ge))
(trap_code_integer_overflow))))
;; output type, and registers containing the source and minimum bound.
(decl fpu_to_int_underflow_check (bool Type Type Reg Reg) Reg)
(rule (fpu_to_int_underflow_check $true $F32 (fits_in_16 out_ty) src min)
(let ((r ValueRegs
(with_flags (fpu_cmp (ScalarSize.Size32) src min)
(ConsumesFlags.ConsumesFlagsReturnsReg
(MInst.TrapIf (cond_br_cond (Cond.Le))
(trap_code_integer_overflow))
src))))
(value_regs_get r 0)))
(rule (fpu_to_int_underflow_check $true $F64 (fits_in_32 out_ty) src min)
(let ((r ValueRegs
(with_flags (fpu_cmp (ScalarSize.Size64) src min)
(ConsumesFlags.ConsumesFlagsReturnsReg
(MInst.TrapIf (cond_br_cond (Cond.Le))
(trap_code_integer_overflow))
src))))
(value_regs_get r 0)))
(rule -1 (fpu_to_int_underflow_check $true in_ty _out_ty src min)
(let ((r ValueRegs
(with_flags (fpu_cmp (scalar_size in_ty) src min)
(ConsumesFlags.ConsumesFlagsReturnsReg
(MInst.TrapIf (cond_br_cond (Cond.Lt))
(trap_code_integer_overflow))
src))))
(value_regs_get r 0)))
(rule (fpu_to_int_underflow_check $false in_ty _out_ty src min)
(let ((r ValueRegs
(with_flags (fpu_cmp (scalar_size in_ty) src min)
(ConsumesFlags.ConsumesFlagsReturnsReg
(MInst.TrapIf (cond_br_cond (Cond.Le))
(trap_code_integer_overflow))
src))))
(value_regs_get r 0)))

(decl fpu_to_int_overflow_check (ScalarSize Reg Reg) Reg)
(rule (fpu_to_int_overflow_check size src max)
(let ((r ValueRegs
(with_flags (fpu_cmp size src max)
(ConsumesFlags.ConsumesFlagsReturnsReg
(MInst.TrapIf (cond_br_cond (Cond.Ge))
(trap_code_integer_overflow))
src))))
(value_regs_get r 0)))

;; Emits the appropriate instruction sequence to convert a
;; floating-point value to an integer, trapping if the value
Expand All @@ -2706,17 +2749,11 @@
(let ((size ScalarSize (scalar_size in_ty))
(in_bits u8 (ty_bits in_ty))
(out_bits u8 (ty_bits out_ty))
(_ InstOutput (side_effect (with_flags_side_effect
(fpu_cmp size src src)
(fpu_to_int_nan_check))))
(src Reg (fpu_to_int_nan_check size src))
(min Reg (min_fp_value signed in_bits out_bits))
(_ InstOutput (side_effect (with_flags_side_effect
(fpu_cmp size src min)
(fpu_to_int_underflow_check signed in_ty out_ty))))
(src Reg (fpu_to_int_underflow_check signed in_ty out_ty src min))
(max Reg (max_fp_value signed in_bits out_bits))
(_ InstOutput (side_effect (with_flags_side_effect
(fpu_cmp size src max)
(fpu_to_int_overflow_check)))))
(src Reg (fpu_to_int_overflow_check size src max)))
(fpu_to_int op src)))

;; Emits the appropriate instruction sequence to convert a
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