Re: My 66000 and High word facility

On Tue, 13 Aug 2024 3:50:04 +0000, BGB wrote:

On 8/12/2024 8:23 PM, MitchAlsup1 wrote:

On Tue, 13 Aug 2024 0:34:55 +0000, BGB wrote:
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On 8/12/2024 5:35 PM, MitchAlsup1 wrote:

On Mon, 12 Aug 2024 20:58:45 +0000, BGB wrote:
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On 8/12/2024 3:12 PM, MitchAlsup1 wrote:

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See polpak:: r8_erf()
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r8_erf:                                 ; @r8_erf

<snip>

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Why don't yuo download polpack, compile it, and state how many
instructions it takes and how many words of storage it takes ??

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Found what I assume you are talking about.
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Needed to add "polpak_test.c" as otherwise BGBCC lacks a main and prunes
everything;
Also needed to hack over some compiler holes related to "complex
_Double" to get it to build;
Also needed to stub over some library functions that were added in C99
but missing in my C library.

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I only ask for r8_erf()

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<snip>
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As for "r8_erf()":
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<===
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r8_erf:

<snip>
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I count 283 instructions compared to my 85 including the 104
instructions
it takes your compiler to get to the 1st instruction in My 66000 code !!
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Yeah, this is a compiler issue...

Why not sit down and code it in ASM to see what your ISA can really do?
Feel free to use My 66000 code as an example.

It might have been less if the code was like:
   static const double somearr[8]={ ... };
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But, this would still have used memory loads.
Getting the constants into expressions would likely require using
#define or similar...
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This is admittedly more how I would have imagined performance-oriented
code to be written. Not so much with dynamically initialized arrays.

That particular piece of code was originally written in FORTRAN
probably late 1960s or early 1970s then ported to C a while back.
<snip>

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But, as I will note, even with this general level of lackluster code
generation, have still been managing to often beat RV64G performance...

Anybody claiming RISC-V has a good ISA should have their degree revoked.