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Add CMO extension intrinsics #93

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Add CMO extension intrinsics #93

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42 changes: 42 additions & 0 deletions src/c-api.adoc
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Original file line number Diff line number Diff line change
Expand Up @@ -485,6 +485,48 @@ RISC-V intrinsics examples:
vint8m1_t __riscv_vadd_vv_i8m1(vint8m1_t vs2, vint8m1_t vs1, size_t vl); // vadd.vv vd, vs2, vs1
----

=== CMO Intrinsics

The RISC-V CMO extension provides instruction for perform operations on copies
of data in the memory hierarchy.

In order to access the RISC-V CMO intrinsics, it is necessary to
include the header file `riscv_cmo.h`.

The functions are only available if the compiler's `-march` string enables the
required ISA extension.

.CMO Extension Intrinsics
[%autowidth]
|===
|*Prototype* |*Instruction* |*Extension* |*Notes*
|`+void __riscv_cmo_clean(void *addr);+` |`cbo.clean` |Zicbom |
|`+void __riscv_cmo_flush(void *addr);+` |`cbo.flush` |Zicbom |
|`+void __riscv_cmo_inval(void *addr);+` |`cbo.inval` |Zicbom |
|`+void __riscv_cmo_zero(void *addr);+` |`cbo.zero` |Zicboz |
|`+void __riscv_cmo_prefetch(void *addr, const int rw, const int locality);+` |`prefetch.[r][w]` |Zicbop | `rw`= [0,1], `locality` = [0..3].
|`+int __riscv_cmo_prefetchi(const int locality);+` |`prefetch.i` |Zicbop |
|===

Note: riscv_cmo_prefetch is a wrapper around builtin_prefetch.
Similar to Prefetch Intrinsics, the following table presents the mapping from
the riscv_cmo_prefetch function to the corresponding assembly instructions,
assuming the presence of the Zihintntl and Zicbop extensions.

.CMO Functions to Assembly Mapping with Zihintntl
[%autowidth]
|===
|*Prefetch function* |*Assembly*
|`+__riscv_cmo_prefetch(ptr, 0, 0 /* locality */);+` |`ntl.all + prefetch.r (ptr)`
|`+__riscv_cmo_prefetch(ptr, 0, 1 /* locality */);+` |`ntl.pall + prefetch.r (ptr)`
|`+__riscv_cmo_prefetch(ptr, 0, 2 /* locality */);+` |`ntl.p1 + prefetch.r (ptr)`
|`+__riscv_cmo_prefetch(ptr, 0, 3 /* locality */);+` |`prefetch.r (ptr)`
|`+__riscv_cmo_prefetch(ptr, 1, 0 /* locality */);+` |`ntl.all + prefetch.w (ptr)`
|`+__riscv_cmo_prefetch(ptr, 1, 1 /* locality */);+` |`ntl.pall + prefetch.w (ptr)`
|`+__riscv_cmo_prefetch(ptr, 1, 2 /* locality */);+` |`ntl.p1 + prefetch.w (ptr)`
|`+__riscv_cmo_prefetch(ptr, 1, 3 /* locality */);+` |`prefetch.w (ptr)`
|===

=== NTLH Intrinsics


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