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Thoughts on Git update (8a9fbce) Added fractional LMUL, including modifying vector data register and vector mask register layouts for SLEN<VLEN implementations.
| First some observations from the revised LMUL.
| *1 The format for a given SLEN and SEW is the same for all LMUL>=1
| *2 LMUL=n is equivalent to LMUL=2 * n with vl < 1/2 vlmax at that level,
| for
| First some observations from the revised LMUL.
| *1 The format for a given SLEN and SEW is the same for all LMUL>=1
| *2 LMUL=n is equivalent to LMUL=2 * n with vl < 1/2 vlmax at that level,
| for
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By
Krste Asanovic
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#107
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Re: [riscv/riscv-v-spec] the differing nature of LMUL > 1 and fractional LMUL (#382)
OK. Again thanks.
I will generate a few versions and compare incrementally.
Will report the anomalies if they show up in your weekend efforts.
OK. Again thanks.
I will generate a few versions and compare incrementally.
Will report the anomalies if they show up in your weekend efforts.
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By
David Horner
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#106
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Re: [riscv/riscv-v-spec] the differing nature of LMUL > 1 and fractional LMUL (#382)
| Thank you very much for this.
| I started a pull request, but was including as an extension and still debating the best way to incorporate.
| Would it be possible to generate a pdf for what is now
| Thank you very much for this.
| I started a pull request, but was including as an extension and still debating the best way to incorporate.
| Would it be possible to generate a pdf for what is now
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By
Krste Asanovic
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#105
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Thoughts on Git update (8a9fbce) Added fractional LMUL, including modifying vector data register and vector mask register layouts for SLEN<VLEN implementations.
First some observations from the revised LMUL.
*1 The format for a given SLEN and SEW is the same for all LMUL>=1
*2 LMUL=n is equivalent to LMUL=2 * n with vl < 1/2 vlmax at that level, for
First some observations from the revised LMUL.
*1 The format for a given SLEN and SEW is the same for all LMUL>=1
*2 LMUL=n is equivalent to LMUL=2 * n with vl < 1/2 vlmax at that level, for
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By
David Horner
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#104
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Re: [riscv/riscv-v-spec] the differing nature of LMUL > 1 and fractional LMUL (#382)
Thank you very much for this.
I started a pull request, but was including as an extension and still debating the best way to incorporate.
Would it be possible
Thank you very much for this.
I started a pull request, but was including as an extension and still debating the best way to incorporate.
Would it be possible
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By
David Horner
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#103
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make SEW be the largest element width
For those not following on github:
On 2020-04-19 1:00 a.m., Krste Asanovic wrote:
.... SEW and LMUL values are essential to correct code execution regardless
For those not following on github:
On 2020-04-19 1:00 a.m., Krste Asanovic wrote:
.... SEW and LMUL values are essential to correct code execution regardless
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By
David Horner
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#102
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Re: Effective element width encoding in vector load/stores
I sent on the wrong email list, so I resend hre.
The cost of narrow to wide is much easier to handle with vlb than with vector arithmetic instructions.
In Bob’s example, it is one instruction
I sent on the wrong email list, so I resend hre.
The cost of narrow to wide is much easier to handle with vlb than with vector arithmetic instructions.
In Bob’s example, it is one instruction
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By
Thang Tran
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#101
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Re: make SEW be the largest element width
First thoughts below
- as a response to #424 and
- we need only consider SEW = LEW (new) and 1/2LEW (POR)
On 2020-04-19 1:00 a.m., Krste Asanovic wrote:
First thoughts below
- as a response to #424 and
- we need only consider SEW = LEW (new) and 1/2LEW (POR)
On 2020-04-19 1:00 a.m., Krste Asanovic wrote:
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By
David Horner
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#100
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make SEW be the largest element width
I added my proposal to github:
https://github.com/riscv/riscv-v-spec/issues/425
appended below for those not following github
Krste
This proposal is a modification of earlier idea to add
I added my proposal to github:
https://github.com/riscv/riscv-v-spec/issues/425
appended below for those not following github
Krste
This proposal is a modification of earlier idea to add
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By
Krste Asanovic
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#99
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Re: RISC-V Vector TG meeting minutes, April 17, 2020
On 2020-04-18 3:14 p.m., Krste Asanovic wrote:
As I had asked that pagan question of opcode space I thought I should try to address the problem:
I opened issue
On 2020-04-18 3:14 p.m., Krste Asanovic wrote:
As I had asked that pagan question of opcode space I thought I should try to address the problem:
I opened issue
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By
David Horner
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#98
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RISC-V Vector TG meeting minutes, April 17, 2020
Also a reminder that the next meeting will be a half hour earlier.
Please check the group's calender for details.
Krste
Date: 2020/4/17
Task Group: Vector Extension
Chair: Krste Asanovic
Number of
Also a reminder that the next meeting will be a half hour earlier.
Please check the group's calender for details.
Krste
Date: 2020/4/17
Task Group: Vector Extension
Chair: Krste Asanovic
Number of
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By
Krste Asanovic
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#97
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Re: Effective element width encoding in vector load/stores
I believe
I believe these widths are the appropriate ones. See the explanation above.
The rationale being widening (and narrowing) instructions are already SEW based, so are single SEW instructions
I believe
I believe these widths are the appropriate ones. See the explanation above.
The rationale being widening (and narrowing) instructions are already SEW based, so are single SEW instructions
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By
David Horner
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#96
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Re: Effective element width encoding in vector load/stores
I really like the fact that this solves indexed.
It's a pretty good proposal overall, and I think it beats adding "quad" extension and then a debate over "quad-with-add", "quad-with-sub",
I really like the fact that this solves indexed.
It's a pretty good proposal overall, and I think it beats adding "quad" extension and then a debate over "quad-with-add", "quad-with-sub",
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By
Roger Espasa
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#95
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Re: Effective element width encoding in vector load/stores
I wonder if we might encode EEW/SEW in the instruction instead of encoding EEW.
We might encode SEW/4, SEW/2, SEW, and 2*SEW as the EEW widths.
Another alternative would be to have an additional
I wonder if we might encode EEW/SEW in the instruction instead of encoding EEW.
We might encode SEW/4, SEW/2, SEW, and 2*SEW as the EEW widths.
Another alternative would be to have an additional
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By
Bill Huffman
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#94
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Re: Effective element width encoding in vector load/stores
Agree. It seems quite nice.
Bill
On 4/16/20 8:30 PM, Bruce Hoult wrote:
Agree. It seems quite nice.
Bill
On 4/16/20 8:30 PM, Bruce Hoult wrote:
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By
Bill Huffman
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#93
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Re: Effective element width encoding in vector load/stores
On 2020-04-16 11:02 p.m., Krste Asanovic wrote:
What of SEW scaling factor instead. 1/4,1/2,1 and 2. This allows a much expanded dynamic range and addresses most scaling concerns.
On 2020-04-16 11:02 p.m., Krste Asanovic wrote:
What of SEW scaling factor instead. 1/4,1/2,1 and 2. This allows a much expanded dynamic range and addresses most scaling concerns.
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By
David Horner
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#92
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Re: Effective element width encoding in vector load/stores
Nice.
By
Bruce Hoult
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#91
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Effective element width encoding in vector load/stores
There are two separate issues noted with the proposal to fixed-size
vector load/stores. One is the additional vsetvli instructions
needed, and the second is the additional widening
There are two separate issues noted with the proposal to fixed-size
vector load/stores. One is the additional vsetvli instructions
needed, and the second is the additional widening
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By
Krste Asanovic
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#90
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intro to #421 Fractional vtype field vfill and #418 vlmt...
Previous issues I opened on fractional LMUL were exploratory, suggesting various ways to encode and enable the feature.
The latest 4 issues opened on github are specific proposals based on the
Previous issues I opened on fractional LMUL were exploratory, suggesting various ways to encode and enable the feature.
The latest 4 issues opened on github are specific proposals based on the
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By
David Horner
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#89
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Re: Vector TG meeting minutes 2020/4/03
I agree, It's more important to gather and evaluate actual application kernels.
Is there such an effort on-going?
I further agree to the implicit idea that much, even most, of the
I agree, It's more important to gather and evaluate actual application kernels.
Is there such an effort on-going?
I further agree to the implicit idea that much, even most, of the
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By
David Horner
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#88
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