Sail Softfloat Replacement #40

jjscheel · 2024-01-30T11:53:16Z

Technical Group

Applications & Tools HC

ratification-pkg

Technical Debt

Technical Liaison

Bill McSpadden

Task Category

Sail

Task Sub Category

Ratification Target

3Q2023

Statement of Work (SOW)

Component names:
Sail

Requirements:
In the RISC-V Sail model, floating point operations are implemented (executed) using the Berkley SoftFloat package (written by John Hauser). See: https://github.com/riscv/sail-riscv/tree/master/c_emulator/SoftFloat-3e
This code is written in C in roughly 320 files and 37K lines of code. (Note: some of this work has already been done in support of Vector Crypto by Charalampos Mitrodimas.)

The functionality in SoftFloat needs to be replicated in native Sail code. The primary purpose of this project is to provide a native Sail description of floating point operations which can be used as the canonical definition of FP ops for RISC-V. This Sail code can be imported into the RISC-V ISA documentation.

The API interface for floating point ops must remain the same.

Deliverables:

Set of Sail files that fully implement the functionality of SoftFloat. The code will live in the RISC-V Sail (golden model) repository.

Acceptance Criteria:

Approved PR to the Sail community for all code.
ACT test results equivalency between new and Softfloat (prior) code bases.

Projected timeframe: (best guess date)
6 person months

SOW Signoffs: (delete those not needed)

Development partner sign-off
Golden Model SIG sign-off (if SAIL work)

Waiver

Freeze
Ratification

Pull Request Details

Float: Add floating-point equals API in sail model - PR #403: Deprecated
Float: Introduce floating point api NAN - #493: Merged
Remove undefined_gen for if-else type float_bits - #516: Merged
Float: Introduce floating point api infinite - #522: Merged
Float: Delete error result file if test pass - #521: Merged
Float: Fix comments typo in test and align space format - #533: Merged
Float: Introduce floating point api sign - #542: Merged
Float: Introduce floating point api zero - #563: Merged

Incarnation-p-lee · 2024-01-31T05:28:40Z

Thank @jjscheel for the clear description of this task.

Hi @billmcspadden-riscv

Just went through the SoftFloat, and would like to double-check if my understanding is correct before any further actions.

Currently, the sail-riscv c_emulator has riscv_softfloat.c, which leverages the SoftFloat library/package. For example, the function softfloat_f64roundToInt depends on the f64_roundToInt (implemented in SoftFloat-3e/source/f64_roundToInt.c). And we need to migrate the c-implemented code to the sail (aka ./model as I understand). Then the e_emulator can leverage the generated code (by sail model) instead of the SoftFloat library/package.

Unfortunately, my previous experience almost focuses on c, java, c#, and of course the green hand for sail. Could you please help to share some guide or something like that as above mentioned that part of works has done for supporting RVV Crypto. I think I need to try some POC by myself first, and then evaluate the efforts, as well as the plan for the task.

CC @haicheng-li

billmcspadden-riscv · 2024-02-06T14:43:49Z

Side comment: Because this is such a large change to the code, we don't want to have a large PR to review. Please consider how you might subdivide the problem such that we only have to review 1000-2000 lines of code at a time. Bill Mc.

…

On Tue, Feb 6, 2024 at 3:15 AM Pan Li ***@***.***> wrote: I summarize what I have learned about the softfloat as below and possible work items. Could you please help to double-check if everything is correct? Then we can start the work step by step. What we have The riscv insn sail models treat the model/riscv_softfloat_interface.sail as the contract of how to leverage the softfloat externally. Like in c_emulator. For example, the sail function riscv_f32Eq in the model/riscv_softfloat_interface.sail will call externally to the function softfloat_f32eq in c_emulator/riscv_softfloat.c. graph LR subgraph The C Emulator B1[softfloat] end subgraph Sail Models A1[riscv-insn-fp-*] --depends on--> A2[riscv_software_interface] --extern call--> B1 end What we would like to do AFAIK, we would like to get rid of the c_mulator/riscv_softfloat, and implement the softfloat in the sail language. And then eliminate the c_emulator/softfloat in this repo. graph LR subgraph The C Emulator B1[softfloat] end subgraph Sail Models A1[riscv-insn-fp-*] --depends on--> A2[riscv_software_interface] --call--> A3[softfloat in sail] A2 x--external call--x B1 end How we land For safe consideration, I may suggest we still treat the model/riscv_softfloat_interface.sai as the contract, and only replace the external call to c_emulator/software one by one. For example: // val extern_f32Eq = {c: "softfloat_f32eq", ocaml: "Softfloat.f32_eq", lem: "softfloat_f32_eq"} : (bits_S, bits_S) -> unit val riscv_softfloat_f32_eq : (bits_S, bits_S) -> unit val riscv_f32Eq : (bits_S, bits_S) -> (bits_fflags, bool) function riscv_f32Eq (v1, v2) = { riscv_softfloat_f32_eq(v1, v2); // extern_f32Eq(v1, v2); (float_fflags[4 .. 0], bit_to_bool(float_result[0])) } Then we only need to implement the sail function riscv_softfloat_f32_eq somewhere else and limit the risk to the existing sail modes. For example, I may suggest we take the below arrangement. And we can even parallel the implementation under softfloat folder once stable. Finally, it looks like we may not need implement everything of e_emulator/software up to a point. model/ ├── README.md ├── riscv_softfloat_interface.sail └── softfloat ├── riscv_softfloat_eq.sail ├── riscv_softfloat_lt.sail └── riscv_softfloat_gt.sail Sail Function to be Implemented According to the API defined in riscv_software_interface, at least we have below sail function to be implemented. - riscv_f16Add - riscv_f16Sub - riscv_f16Mul - riscv_f16Div - riscv_f32Add - riscv_f32Sub - riscv_f32Mul - riscv_f32Div - riscv_f64Add - riscv_f64Sub - riscv_f64Mul - riscv_f64Div - riscv_f16MulAdd - riscv_f32MulAdd - riscv_f64MulAdd - riscv_f16Sqrt - riscv_f32Sqrt - riscv_f64Sqrt - riscv_f16ToI32 - riscv_f16ToUi32 - riscv_i32ToF16 - riscv_ui32ToF16 - riscv_f16ToI64 - riscv_f16ToUi64 - riscv_i64ToF16 - riscv_ui64ToF16 - riscv_f32ToI32 - riscv_f32ToUi32 - riscv_i32ToF32 - riscv_ui32ToF32 - riscv_f32ToI64 - riscv_f32ToUi64 - riscv_i64ToF32 - riscv_ui64ToF32 - riscv_f64ToI32 - riscv_f64ToUi32 - riscv_i32ToF64 - riscv_ui32ToF64 - riscv_f64ToI64 - riscv_f64ToUi64 - riscv_i64ToF64 - riscv_ui64ToF64 - riscv_f16ToF32 - riscv_f16ToF64 - riscv_f32ToF64 - riscv_f32ToF16 - riscv_f64ToF16 - riscv_f64ToF32 - riscv_f16Lt - riscv_f16Lt_quiet - riscv_f16Le - riscv_f16Le_quiet - riscv_f16Eq - riscv_f32Lt - riscv_f32Lt_quiet - riscv_f32Le - riscv_f32Le_quiet - riscv_f32Eq - riscv_f64Lt - riscv_f64Lt_quiet - riscv_f64Le - riscv_f64Le_quiet - riscv_f64Eq - riscv_f16roundToInt - riscv_f32roundToInt - riscv_f64roundToIn Issues I am working on one POC of a simple API like f32eq, and there are some global variables like floating control and status flags .. etc, will keep you all posted. CC @haicheng-li <https://github.com/haicheng-li> for awareness. — Reply to this email directly, view it on GitHub <#40 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AXROLOBBJI7DAEHKNTYW3ODYSIGF3AVCNFSM6AAAAABCRDLEGSVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMYTSMRZGMYDCMZQG4> . You are receiving this because you were mentioned.Message ID: ***@***.***>

-- Bill McSpadden Formal Verification Engineer RISC-V International mobile: 503-807-9309

Incarnation-p-lee · 2024-02-07T00:51:09Z

Sure thing, actually I may prefer 200-300(excludes test code) lines per PR for review. By the way, does sail-riscv repo take Merge or Squash Merge for PR?

Incarnation-p-lee · 2024-03-04T01:28:58Z

Status Update Mar 4, 2024

PR Float Equal updated in Feb 16, 2024, waiting for further review.

Incarnation-p-lee · 2024-03-06T01:40:58Z

Thanks @jjscheel for the SOW description. ACK the SOW from my side.

To clarify, please feel free to comment if any concerns or questions about below open issue.

The softfloat_3e_test porting to sail-riscv is NOT in the scope of this SOW due to some more support required from the sail compiler. If so I think we need to record it by a task somewhere.

billmcspadden-riscv · 2024-03-06T15:29:05Z

Hi Pan. Would you please explain a bit more about "more support required from the sail compiler". As I understand it, TestFloat is a set of tests for checking the implementation of a binary floating point library. How does this have anything to do with the Sail compiler? Bill Mc.

…

On Tue, Mar 5, 2024 at 5:41 PM Pan Li ***@***.***> wrote: Thanks @jjscheel <https://github.com/jjscheel> for the SOW description. ACK the SOW from my side. To clarify, please feel free to comment if any concerns or questions about below open issue. - The softfloat_3e_test <http://www.jhauser.us/arithmetic/TestFloat.html> porting to sail-riscv is *NOT* in the scope of this SOW due to some more support required from the sail compiler. If so I think we need to record it by a task somewhere. — Reply to this email directly, view it on GitHub <#40 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AXROLOCJ7KFM3Q3JCODASDLYWZX3NAVCNFSM6AAAAABCRDLEGSVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMYTSNZZHEZDKNZYGE> . You are receiving this because you were mentioned.Message ID: ***@***.***>

-- Bill McSpadden Formal Verification Engineer RISC-V International mobile: 503-807-9309

Incarnation-p-lee · 2024-03-06T23:25:00Z

Hi Bill,

Hope you get better and recover soon. To port the TestFloat to the repo sail-riscv, Tim has a proposal requires some update in sail compiler if my understanding is correct.

The idea is that we can port these test cases to sail similar as SoftFloat and find a place to run/execute them(as one of the target of makefile).

ptomsich · 2024-03-06T23:42:24Z

The compiler changes would be required to automatically run both implementations (i.e., in lockstep) and compare the results.

The referenced [http://www.jhauser.us/arithmetic/TestFloat.html](Berkeley TestFloat) is a black-box FP test-suite.
Having a test-suite for the IEEE-FP compliance in the repository (and running it as part of the CI/CD against the generated c_simulator) would be a great idea.

Incarnation-p-lee · 2024-03-18T06:16:08Z

Status Update Mar 18, 2024

PR Float Equal updated in Feb 16, 2024, waiting for further review.

jjscheel · 2024-03-19T21:18:12Z

@billmcspadden-riscv, please reach out to @Incarnation-p-lee and @haicheng-li about the Testing Process which has been proposed by the Golden Model SIG and how to proceed with this work. Thanks!

jjscheel · 2024-04-01T13:54:41Z

Note: We've extracted the verification work associated with the new Sail replacement for softfloat into issue #41. So, acceptance of this item will require successful passing of the verification work, but the actual work and discussion associated with building and performing the verification will be in the new issue.

Incarnation-p-lee · 2024-04-03T08:49:22Z

Floating Point API Design for Sail

[TOC]

Motivation

Currently the sail-riscv take the c-implemented softfloat to perform the floating-point related operations. However, it is not the sail code which can be transformed to any other modeling validation tools. Thus, we would like to replace the c-implemented softfloat into the sail native way.

Given that floating-point is one more general concept above the sail-riscv, it is even better to port the c-implemented softfloat as a standalone sail library and then integrated into the sail-riscv when fully verified.

Goal

The floating-point API for a standalone sail library.

Pull Request

API(s)

Exception and Rounding Modes

Floating-point Exception Flags

Flags	NV	DZ	OF	UF	NX
Full-name	invalid operation	divide by zero	overflow	underflow	inexact
Value	0b1	0b10	0b100	0b1000	0b10000

Floating-point exception flags takes 5 bits.

Floating-point Rounding Modes

Modes	RNE	RNA	RDN	RUP	RTZ
Full-name	round to nearest, ties to even	round to nearest, ties to away	round down	round up	round towards zero
Value	1	2	3	4	5

Floating-point rounding modes take 5 bits.

Mechanism

The rounding mode will be implemented as read/write global variables, default to RNE.
The exception will be implemented as part of the API return value(s) if required.
The rounding mode is sticking, while the exception isn't.

API Details

All API(s) support half, single and double precision floating-point, aka FP16, FP32 and FP64. Each API will leverage the existing rounding mode unless you explicit specific the rounding mode or by float_set_rounding before invoke the API. Meanwhile, the flags_mask allows you to mask some exception flags if you don't want it.

Type(s) Definition

Name	Description
`FP_N`	Floating-point with N bits, N can be 16, 32 or 64, aka half, single and double floating-point.
`exception_flags`	Floating-point exception flags within 5 bits.
`rounding_mode`	Floating-point rounding mode within 5 bits.
`INT_N`	Signed Integer with N bits, N can be 16, 32 or 64.
`UINT_N`	Unsigned Integer with N bits, N can be 16, 32 or 64.

`float_is_nan`

The floating-point is NAN or not, return true if NAN, or false.

bool float_is_nan (FP_N);

Exception Flags

Flags	NV	DZ	OF	UF	NX
Raise	N	N	N	N	N

Rounding Modes
- This API doesn't honor rounding modes.

`float_is_qnan`

The floating-point is QNAN or not, return true if QNAN, or false.

bool float_is_qnan (FP_N);

Exception Flags

Flags	NV	DZ	OF	UF	NX
Raise	N	N	N	N	N

Rounding Modes
- This API doesn't honor rounding modes.

`float_is_snan`

The floating-point is SNAN or not, return true if nan, or false.

bool float_is_snan (FP_N);

Exception Flags

Flags	NV	DZ	OF	UF	NX
Raise	N	N	N	N	N

Rounding Modes
- This API doesn't honor rounding modes.

`float_is_inf`

The floating-point is infinite or not, return true if infinite, or false.

bool float_is_inf (FP_N);

Exception Flags

Flags	NV	DZ	OF	UF	NX
Raise	N	N	N	N	N

Rounding Modes
- This API doesn't honor rounding modes.

`float_is_positive`

The floating-point is positive or not, return true if positive, or false.

bool float_is_positive (FP_N);

Exception Flags

Flags	NV	DZ	OF	UF	NX
Raise	N	N	N	N	N

Rounding Modes
- This API doesn't honor rounding modes.

`float_is_negative`

The floating-point is negative or not, return true if negative, or false.

bool float_is_negative (FP_N);

Exception Flags

Flags	NV	DZ	OF	UF	NX
Raise	N	N	N	N	N

Rounding Modes
- This API doesn't honor rounding modes.

`float_is_zero`

The floating-point is zero or not, return true if z,ero or false.

bool float_is_zero (FP_N);

Exception Flags

Flags	NV	DZ	OF	UF	NX
Raise	N	N	N	N	N

Rounding Modes
- This API doesn't honor rounding modes.

`float_is_normal`

The floating-point is normal or not, return true if normal, or false.

bool float_is_normal (FP_N);

Exception Flags

Flags	NV	DZ	OF	UF	NX
Raise	N	N	N	N	N

Rounding Modes
- This API doesn't honor rounding modes.

`float_is_denormal`

The floating-point is denormal or not, return true if denormal, or false.

bool float_is_denormal (FP_N);

Exception Flags

Flags	NV	DZ	OF	UF	NX
Raise	N	N	N	N	N

Rounding Modes
- This API doesn't honor rounding modes.

`float_eq`

The floating-point equals, return true if op_1 is equal to op_2, or false.

(bool, exception_flags) float_eq ((FP_N, FP_N));

Exception Flags

Flags	NV	DZ	OF	UF	NX
Raise	Y	N	N	N	N

Rounding Modes
- This API doesn't honor rounding modes.

`float_ne`

The floating-point not equals, return true if op_1 is equal to op_2, or false.
$$
(bool, flags) = op_1 \ne op_2
$$

(bool, exception_flags) float_ne ((FP_N, FP_N));

Exception Flags

Flags	NV	DZ	OF	UF	NX
Raise	Y	N	N	N	N

Rounding Modes
- This API doesn't honor rounding modes.

`float_lt`

The floating-point less than, return true if op_1 is less than op_2, or false.

(bool, exception_flags) float_lt ((FP_N, FP_N));

Exception Flags

Flags	NV	DZ	OF	UF	NX
Raise	Y	N	N	N	N

Rounding Modes
- This API doesn't honor rounding modes.

`float_lt_quiet`

Similar to float_lt but only raise NV when op_1 and/or op_2 is SNAN.

(bool, exception_flags) float_lt_quiet ((FP_N, FP_N));

Exception Flags

Flags	NV	DZ	OF	UF	NX
Raise	Y	N	N	N	N

Rounding Modes
- This API doesn't honor rounding modes.

`float_le`

The floating-point less than or equal, return true if op_1 is less than or equal to op_2, or false.

(bool, exception_flags) float_le ((FP_N, FP_N));

Exception Flags

Flags	NV	DZ	OF	UF	NX
Raise	Y	N	N	N	N

Rounding Modes
- This API doesn't honor rounding modes.

`float_le_quiet`

Similar to float_le but only raise NV when op_1 and/or op_2 is SNAN.

(bool, exception_flags) float_le_quiet ((FP_N, FP_N));

Exception Flags

Flags	NV	DZ	OF	UF	NX
Raise	Y	N	N	N	N

Rounding Modes
- This API doesn't honor rounding modes.

`float_gt`

The floating-point greater than, return true if op_1 is greater than op_2, or false.

(bool, exception_flags) float_gt ((FP_N, FP_N));

Exception Flags

Flags	NV	DZ	OF	UF	NX
Raise	Y	N	N	N	N

Rounding Modes
- This API doesn't honor rounding modes.

`float_gt_quiet`

Similar to float_gt but only raise NV when op_1 and/or op_2 is SNAN.

(bool, exception_flags) float_gt_quiet ((FP_N, FP_N));

Exception Flags

Flags	NV	DZ	OF	UF	NX
Raise	Y	N	N	N	N

Rounding Modes
- This API doesn't honor rounding modes.

`float_ge`

The floating-point greater than or equal, return true if op_1 is greater than or equal to op_2, or false.

(bool, exception_flags) float_ge ((FP_N, FP_N));

Exception Flags

Flags	NV	DZ	OF	UF	NX
Raise	Y	N	N	N	N

Rounding Modes
- This API doesn't honor rounding modes.

`float_ge_quiet`

Similar to float_ge but only raise NV when op_1 and/or op_2 is SNAN.

(bool, exception_flags) float_ge_quiet ((FP_N, FP_N op_2));

Exception Flags

Flags	NV	DZ	OF	UF	NX
Raise	Y	N	N	N	N

Rounding Modes
- This API doesn't honor rounding modes.

`float_add`

The floating-point add, aka:

(FP_N, exception_flags) float_add ((FP_N, FP_N));
(FP_N, exception_flags) float_add_by_config ((FP_N, FP_N), rounding_mode mode, exception_flags flags_mask);

Exception Flags

You can leverage flags_mask to disable the exception_flags before return. For example, passing flags_unmask_inexact(0b01111) will never set inexact_flag when add.

Flags	NV	DZ	OF	UF	NX
Raise	Y	N	Y	Y	Y

Rounding Modes
- This API honors rounding modes.
- The _by_config API(s) will pollute the global rounding modes.
- The _by_config API(s) will mask the exception before return.

`float_sub`

The floating-point sub, aka:

(FP_N, exception_flags) float_sub ((FP_N op_1, FP_N op_2));
(FP_N, exception_flags) float_sub_by_config ((FP_N, FP_N), rounding_mode mode, exception_flags flags_mask);

Exception Flags

Flags	NV	DZ	OF	UF	NX
Raise	Y	N	Y	Y	Y

Rounding Modes
- This API honors rounding modes.
- The _by_config API(s) will pollute the global rounding modes.
- The _by_config API(s) will mask the exception before return.

`float_mul`

The floating-point mul, aka:

(FP_N, exception_flags) float_mul ((FP_N, FP_N));
(FP_N, exception_flags) float_mul_by_config ((FP_N, FP_N), rounding_mode mode, exception_flags flags_mask);

Exception Flags

Flags	NV	DZ	OF	UF	NX
Raise	Y	N	Y	Y	Y

Rounding Modes
- This API honors rounding modes.
- The _by_config API(s) will pollute the global rounding modes.
- The _by_config API(s) will mask the exception before return.

`float_div`

The floating-point div, aka:

(FP_N, exception_flags) float_div ((FP_N, FP_N));
(FP_N, exception_flags) float_div_by_config ((FP_N, FP_N), rounding_mode mode, exception_flags flags_mask);

Exception Flags

Flags	NV	DZ	OF	UF	NX
Raise	Y	Y	Y	Y	Y

Rounding Modes
- This API honors rounding modes.
- The _by_config API(s) will pollute the global rounding modes.
- The _by_config API(s) will mask the exception before return.

`float_mul_add`

The floating-point mul_add, aka:

(FP_N, exception_flags) float_mul_add ((FP_N, FP_N, FP_N));
(FP_N, exception_flags) float_mul_add_by_config ((FP_N, FP_N, FP_N), rounding_mode mode, exception_flags flags_mask);

Exception Flags

Flags	NV	DZ	OF	UF	NX
Raise	Y	N	Y	Y	Y

Rounding Modes
- This API honors rounding modes.
- The _by_config API(s) will pollute the global rounding modes.
- The _by_config API(s) will mask the exception before return.

`float_sqrt`

The floating-point sqrt, aka:

(FP_N, exception_flags) float_sqrt (FP_N);
(FP_N, exception_flags) float_sqrt_by_config (FP_N, rounding_mode mode, exception_flags flags_mask);

Exception Flags

Flags	NV	DZ	OF	UF	NX
Raise	Y	N	Y	Y	Y

Rounding Modes
- This API honors rounding modes.
- The _by_config API(s) will pollute the global rounding modes.
- The _by_config API(s) will mask the exception before return.

`float_to_i32`

The floating-point converting to signed INT_N, N = 32 aka:

(INT_N, exception_flags) float_to_i32 (FP_N);
(INT_N, exception_flags) float_to_i32_by_config (FP_N, rounding_mode mode, exception_flags flags_mask);

Exception Flags

Flags	NV	DZ	OF	UF	NX
Raise	Y	N	Y	Y	Y

Rounding Modes
- This API honors rounding modes.
- The _by_config API(s) will pollute the global rounding modes.
- The _by_config API(s) will mask the exception before return.

`float_to_i16`

Almost the same as float_to_i32 except the INT_N bit size.

`float_to_i64`

Almost the same as float_to_i32 except the INT_N bit size.

`float_to_u32`

The floating-point converting to unsigned UINT_N, N = 32 aka:

(UINT_N, exception_flags) float_to_u32 (FP_N);
(UINT_N, exception_flags) float_to_u32_by_config (FP_N, rounding_mode mode, exception_flags flags_mask);

Exception Flags

Flags	NV	DZ	OF	UF	NX
Raise	Y	N	Y	Y	Y

Rounding Modes
- This API honors rounding modes.
- The _by_config API(s) will pollute the global rounding modes.
- The _by_config API(s) will mask the exception before return.

`float_to_u16`

Almost the same as float_to_u32 except the UINT_N bit size.

`float_to_u64`

Almost the same as float_to_u32 except the UINT_N bit size.

`float_from_s32`

The floating-point converting from signed INT_N, N = 32 aka:

(FP_N, exception_flags) float_from_s32 (INT_N);
(FP_N, exception_flags) float_from_s32_by_config (INT_N, rounding_mode mode, exception_flags flags_mask);

Exception Flags

Flags	NV	DZ	OF	UF	NX
Raise	Y	N	Y	Y	Y

Rounding Modes
- This API honors rounding modes.
- The _by_config API(s) will pollute the global rounding modes.
- The _by_config API(s) will mask the exception before return.

`float_from_i16`

Almost the same as float_from_i32 except the INT_N bit size.

`float_from_i64`

Almost the same as float_from_i32 except the INT_N bit size.

`float_from_u32`

The floating-point converting from unsigned UINT_N, N = 32 aka:

(FP_N, exception_flags) float_from_u32 (UINT_N);
(FP_N, exception_flags) float_from_u32_by_config (UINT_N, rounding_mode mode, exception_flags flags mask);

Exception Flags

Flags	NV	DZ	OF	UF	NX
Raise	Y	N	Y	Y	Y

Rounding Modes
- This API honors rounding modes.
- The _by_config API(s) will pollute the global rounding modes.
- The _by_config API(s) will mask the exception before return.

`float_from_u16`

Almost the same as float_from_u32 except the UINT_N bit size.

`float_from_u64`

Almost the same as float_from_u32 except the UINT_N bit size.

`float_to_f32`

The floating-point converting to FP_N, N = 32 aka:

(FP_N, exception_flags) float_to_f32 (FP_N);
(FP_N, exception_flags) float_to_f32_by_config (FP_N, rounding_mode mode, exception_flags flags_mask);

Exception Flags

Flags	NV	DZ	OF	UF	NX
Raise	Y	N	Y	Y	Y

Rounding Modes
- This API honors rounding modes.
- The _by_config API(s) will pollute the global rounding modes.
- The _by_config API(s) will mask the exception before return.

`float_to_f16`

Almost the same as float_to_f16 except the FP_N bit size.

`float_to_f64`

Almost the same as float_to_f16 except the FP_N bit size.

`float_round_to_int`

The floating-point round to nearest integer in FP_N, aka:

(FP_N, exception_flags) float_round_to_int (FP_N);
(FP_N, exception_flags) float_round_to_int_by_config (FP_N, rounding_mode mode, exception_flags flags_mask);

Exception Flags

Flags	NV	DZ	OF	UF	NX
Raise	Y	N	Y	Y	Y

Rounding Modes
- This API honors rounding modes.
- The _by_config API(s) will pollute the global rounding modes.
- The _by_config API(s) will mask the exception before return.

`float_set_rounding`

The floating-point set rounding modes.

(rounding_mode) float_set_rounding (rounding_mode mode);

Exception Flags

Flags	NV	DZ	OF	UF	NX
Raise	N	N	N	N	N

Rounding Modes
- This API will pollute the global rounding modes.

Reference Link

Incarnation-p-lee · 2024-04-03T08:51:13Z

Hi @jjscheel and @billmcspadden-riscv

Just draft the API(s) of sail float, please feel free to comment if any questions or concerns.

CC @haicheng-li for awarness.

jjscheel · 2024-04-03T10:44:00Z

Nice, @Incarnation-p-lee. THANKS!

Incarnation-p-lee · 2024-04-16T12:00:09Z

Status Update Apr 16, 2024

Draft the API design doc as above.
Work out one POC for the standalone float lib.

jjscheel · 2024-04-30T15:31:38Z

@Incarnation-p-lee, how is the POC going?

Incarnation-p-lee · 2024-05-01T01:32:14Z

Status Update Apr 30, 2024

Most implementation of NAN completed.
Working on how to test it in sail mode.

Incarnation-p-lee · 2024-05-01T01:32:57Z

@Incarnation-p-lee, how is the POC going?

Sorry for missing the status update, happy holiday, ;)!

jjscheel · 2024-05-01T12:24:08Z

No worries. Happy holiday to you!

Incarnation-p-lee · 2024-05-07T00:14:09Z

Hi @jjscheel
Just FYI that all PR can be found around the end of the API design doc. For example:

Incarnation-p-lee · 2024-05-14T06:15:58Z

Status Update Mar 14, 2024

The NAN API Merged with test.
The Infinite API Under Review.

jjscheel · 2024-05-14T11:24:39Z

Thanks, @Incarnation-p-lee. Can you explain why your SAIL work is in the rems-project and not sail-riscv?

Incarnation-p-lee · 2024-05-14T13:40:05Z

Thanks, @Incarnation-p-lee. Can you explain why your SAIL work is in the rems-project and not sail-riscv?

We promote the float to a standalone lib, thus SAIL will be a better place here. Because not only sail-riscv can leverage this library.

jjscheel · 2024-05-16T12:17:53Z

Ah, yes! I now understand. Thanks, @Incarnation-p-lee!!!

Incarnation-p-lee · 2024-05-27T06:56:05Z

Status Update Mar 28, 2024

The minor fix/improvement for the test framework Merged.
The Infinite API Merged with test cases.
The sign API Merged with test cases.
The zero API is Under Review.

jjscheel · 2024-05-28T17:54:26Z

@Incarnation-p-lee, it appears ALL your PRs have now merged. Congrats. Does this mean your library is fully implemented?

jrtc27 · 2024-05-28T18:02:44Z

Compare the list of APIs to the much smaller list of things covered by the PRs that exist to date. It's a big chunk of work to get through.

Incarnation-p-lee · 2024-05-28T23:18:23Z

Thanks @jrtc27 for the explanation. That is correct, there are lots of API that need to be covered, I think the overall progress is about 10%, give or take.

Incarnation-p-lee · 2024-06-11T02:37:36Z

Status Update Jun 11, 2024

The zero API is Merged with test cases.
The normal API is Merged with test cases.
The equal API is Under Review.

Incarnation-p-lee · 2024-06-24T14:49:05Z

Status Update Jun 25, 2024

The equal API is Merged with test cases.
The not equal API is Merged with test cases.
The quad float (aka fp128) is supported for all existing APIs, thanks to @jordancarlin.
The test data refactor is Under Review.

Incarnation-p-lee · 2024-07-09T05:40:16Z

Status Update Jul 9, 2024

The test data refactor is Merged.
The less than API is Merged with test cases.
The duplicated code refactor is Under Review.

Incarnation-p-lee · 2024-08-20T04:52:08Z

Status Update Aug 20, 2024

The equal related refactor is Merged.
The less than or eq (le) API is Under Review.
The include files clean up is Under Review.

Incarnation-p-lee · 2024-09-02T05:15:43Z

Status Update Sep 3, 2024

The less than or eq (le) API is Merged.
The less than or eq (le) quiet API is Merged.
The including files clean up is Merged.
The greater than (gt) API is Under Review.

Incarnation-p-lee · 2024-09-17T03:26:56Z

Status Update Sep 17, 2024

The greater than (gt) API is Merged.
The greater than (gt) quiet API is Merged.
The greater than or equal (ge) API is Merged.
The greater than or equal (ge) quiet API is Under Review.

haicheng-li · 2024-10-01T11:42:14Z

Status Update Oct 1, 2024

The greater than or equal (ge) quiet API is Merged.

Incarnation-p-lee · 2024-10-01T12:54:30Z

Status Update Oct 1, 2024

The greater than or equal (ge) quiet API is Merged.

Thanks, Haicheng, try to update just now and find yours.

Note: we are on the National Holiday Vacation from 10/01 to 10/07.

Incarnation-p-lee · 2024-10-15T11:10:48Z

Status Update Oct 15, 2024

All API except ALU are Merged.
The add API is implementing.

Incarnation-p-lee · 2024-10-29T06:12:54Z

Status Update Oct 29, 2024

Still discuss with maintainer for the implementation details of float add.

Incarnation-p-lee · 2024-11-12T06:20:47Z

Status Update Nov 12, 2024

The patch for float add (denormal and infinite part) is Under Review.

jjscheel added the Agenda Item label Jan 30, 2024

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jjscheel mentioned this issue Apr 1, 2024

Sail Softfloat Replacement Verification #41

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Sail Softfloat Replacement #40

Sail Softfloat Replacement #40

Comments

jjscheel commented Jan 30, 2024 • edited Loading

Technical Group

ratification-pkg

Technical Liaison

Task Category

Task Sub Category

Ratification Target

Statement of Work (SOW)

Waiver

Pull Request Details

Incarnation-p-lee commented Jan 31, 2024

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billmcspadden-riscv commented Feb 6, 2024 via email

Incarnation-p-lee commented Feb 7, 2024

Incarnation-p-lee commented Mar 4, 2024 • edited Loading

Status Update Mar 4, 2024

Incarnation-p-lee commented Mar 6, 2024

billmcspadden-riscv commented Mar 6, 2024 via email

Incarnation-p-lee commented Mar 6, 2024

ptomsich commented Mar 6, 2024

Incarnation-p-lee commented Mar 18, 2024

Status Update Mar 18, 2024

jjscheel commented Mar 19, 2024

jjscheel commented Apr 1, 2024

Incarnation-p-lee commented Apr 3, 2024 • edited Loading

Table of contents

Floating Point API Design for Sail

Motivation

Goal

Pull Request

API(s)

Exception and Rounding Modes

Floating-point Exception Flags

Floating-point Rounding Modes

Mechanism

API Details

Type(s) Definition

float_is_nan

float_is_qnan

float_is_snan

float_is_inf

float_is_positive

float_is_negative

float_is_zero

float_is_normal

float_is_denormal

float_eq

float_ne

float_lt

float_lt_quiet

float_le

float_le_quiet

float_gt

float_gt_quiet

float_ge

float_ge_quiet

float_add

float_sub

float_mul

float_div

float_mul_add

float_sqrt

float_to_i32

float_to_i16

float_to_i64

float_to_u32

float_to_u16

float_to_u64

float_from_s32

float_from_i16

float_from_i64

float_from_u32

float_from_u16

float_from_u64

float_to_f32

float_to_f16

float_to_f64

jjscheel commented Jan 30, 2024 •

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Incarnation-p-lee commented Mar 4, 2024 •

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Incarnation-p-lee commented Apr 3, 2024 •

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`float_is_nan`

`float_is_qnan`

`float_is_snan`

`float_is_inf`

`float_is_positive`

`float_is_negative`

`float_is_zero`

`float_is_normal`

`float_is_denormal`

`float_eq`

`float_ne`

`float_lt`

`float_lt_quiet`

`float_le`

`float_le_quiet`

`float_gt`

`float_gt_quiet`

`float_ge`

`float_ge_quiet`

`float_add`

`float_sub`

`float_mul`

`float_div`

`float_mul_add`

`float_sqrt`

`float_to_i32`

`float_to_i16`

`float_to_i64`

`float_to_u32`

`float_to_u16`

`float_to_u64`

`float_from_s32`

`float_from_i16`

`float_from_i64`

`float_from_u32`

`float_from_u16`

`float_from_u64`

`float_to_f32`

`float_to_f16`

`float_to_f64`

`float_round_to_int`

`float_set_rounding`

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Incarnation-p-lee commented May 14, 2024 •

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Incarnation-p-lee commented Jun 24, 2024 •

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