Saturday, 2022-03-12

programmerjakelkcl: mithro replied:
*** alMalsamo is now known as lumberjack12305:14
lkclwell, not a "biiiig" deal, but yeah, "lanes" only makes sense at the internal-hardware-level, for hardware-architects to have a term whereby they can refer to the parallel pathways in a SIMD ALU09:23
lkclwith a SIMD ISA the numbering on the lanes unfortunately become synonymous with (identical to) the numbering on the elements at the ISA level09:24
lkclhence the confusion.09:24
lkclhowever for say the Broadcom VideoCore IV which can do "Virtual Elements", that's where [one of many of] the problems start09:25
lkclVideoCore IV's FPU has only a 4-lane-wide internal SIMD ALU but it has a hardware-for-loop to make it *look* like it has *16* actual elements09:26
lkclyou issue a 16-element-wide instruction at the *ISA* level that gets broken down such that elements 0,4,8,12 are all fed to Lane 0 of the hardware, elements 1,5,9,13 to Lane 1 of the hardware....09:27
lkclprogrammerjake, yep, mithro's worked out that this is like "patching binaries" rather than fixing the problem at the c-source-code level.09:31
lkclexpecting gcc, llvm, intel-c-compiler and msvc to all re-construct a high-level programming concept after it's been compiled to assembler (or lower)09:43
lkclwhereas [slightly off-topic for the bug] if the symbiflow hack-in-python to morph the chain-of-carry4s into a proper carry-lookahead-tree were instead added as a yosys techmap pass, then every one of the free software P&Rs benefits, everyone has significantly less work to do,09:46
lkcland, hilariously, i suspect that resource efficiency on the xilinx proprietary P&R would go up as well09:46
lkcltoshywoshy, openpowerbot_ needs poking with a stick on this channel, mattermost10:52
lkcland #microwatt it seems. not getting through to oftc either10:52
octaviuslkcl....guess who had forgotten his m.d.comb prefix? XD16:09
lkcloctavius, been there :)16:11
octaviusThat's half the fun I guess16:13
octaviusWell, good thing is I can get on with it now16:14
lkcljoy and celebration.16:14
* lkcl said in the voice of Douglas Adam's "Marvin the Paranoid Android" of course16:15
lkclbrain the size of a planet, and what have they got me doing? parking cars for a million years.16:31
cesarlkcl: I am creating a new file (src/soc/regfile/ Should I put a header with licencing, copyright and sponsor information? Something like the one in src/soc/bus/
cesarIf so, what would be the sponsoring information for this particular work (the SRAM wrapper, bug 781)?21:26
lkclcesar, yes21:35
lkclsame. that basically becomes the default template, now, really21:35
cesarGot it, thanks.21:36

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