Add CMO extension intrinsics #93
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src/c-api.adoc
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| |`+void __riscv_cbo_flush(void *addr);+` |`cbo.flush` |Zicbom | ||
| |`+void __riscv_cbo_inval(void *addr);+` |`cbo.inval` |Zicbom | ||
| |`+void __riscv_cbo_zero(void *addr);+` |`cbo.zero` |Zicboz | ||
| |`+void __riscv_cbo_prefetch(void *addr, const int rw, const int locality);+` |`prefetch.[r][w]` |Zicbop |
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Is __riscv_cbo_prefetch a wrapper around __builtin_prefetch where there are 4 possible localities? RISC-V supports 5 localities, 4 NTL hint prefixes and 1 without any prefix.
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Yes, this is __builtin_prefetch's wrapper. The 4 NTL hint maping had been included in Prefetch Intrinsics part on this doc. So, this commit only support a wrapper for __builtin_prefetch on zicbop extension.
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Can you document how the different rw/locality map to different instruction sequences?
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Can you document how the different rw/locality map to different instruction sequences?
Do you mean to expand to describe these mappings?
Ok, I will send a new version tomorrow.
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I follow the documentation to set the __riscv_cbo_prefetchi parameter type, but I get such an error that is invalid argument to built-in function. So, I think the authour need to redefine the parameter type. |
The rw and locality argument to __builtin_prefetch must be compile time constants. You'll need to use a macro instead of a function. |
src/c-api.adoc
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| ---- | ||
| void __riscv_cbo_prefetch(void *addr, const int rw, const int locality) | ||
| { | ||
| __builtin_prefetch(addr, rw, locality); |
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We need to explain that locality==0, adds nt.all hint. locality==1, adds ntl.pall hint. locality==2, adds ntl.p1 hint.
Add CMO extension intrinsics description.