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lavu/cpu: CPU flags for the RISC-V Vector extension

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RVV defines a total of 12 different extensions, including:

- 5 different instruction subsets:
  - Zve32x: 8-, 16- and 32-bit integers,
  - Zve32f: Zve32x plus single precision floats,
  - Zve64x: Zve32x plus 64-bit integers,
  - Zve64f: Zve32f plus Zve64x,
  - Zve64d: Zve64f plus double precision floats.

- 6 different vector lengths:
  - Zvl32b (embedded only),
  - Zvl64b (embedded only),
  - Zvl128b,
  - Zvl256b,
  - Zvl512b,
  - Zvl1024b,

- and the V extension proper: equivalent to Zve64f and Zvl128b.

In total, there are 6 different possible sets of supported instructions
(including the empty set), but for convenience we allocate one bit for
each type sets: up-to-32-bit ints (RVV_I32), floats (RVV_F32),
64-bit ints (RVV_I64) and doubles (RVV_F64).

Whence the vector size is needed, it can be retrieved by reading the
unprivileged read-only vlenb CSR. This should probably be a separate
helper macro if needed at a later point.
This commit is contained in:
Rémi Denis-Courmont
2022-09-26 17:52:25 +03:00
committed by Lynne
parent 1edac8eb46
commit 0c0a3deb18
4 changed files with 31 additions and 0 deletions
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4
libavutil/cpu.c
View File

@@ -184,6 +184,10 @@ int av_parse_cpu_caps(unsigned *flags, const char *s)
{ "rvi", NULL, 0, AV_OPT_TYPE_CONST, { .i64 = AV_CPU_FLAG_RVI }, .unit = "flags" },
{ "rvf", NULL, 0, AV_OPT_TYPE_CONST, { .i64 = AV_CPU_FLAG_RVF }, .unit = "flags" },
{ "rvd", NULL, 0, AV_OPT_TYPE_CONST, { .i64 = AV_CPU_FLAG_RVD }, .unit = "flags" },
{ "rvv-i32", NULL, 0, AV_OPT_TYPE_CONST, { .i64 = AV_CPU_FLAG_RVV_I32 }, .unit = "flags" },
{ "rvv-f32", NULL, 0, AV_OPT_TYPE_CONST, { .i64 = AV_CPU_FLAG_RVV_F32 }, .unit = "flags" },
{ "rvv-i64", NULL, 0, AV_OPT_TYPE_CONST, { .i64 = AV_CPU_FLAG_RVV_I64 }, .unit = "flags" },
{ "rvv", NULL, 0, AV_OPT_TYPE_CONST, { .i64 = AV_CPU_FLAG_RVV_F64 }, .unit = "flags" },
#endif
{ NULL },
};

4
libavutil/cpu.h
View File

@@ -82,6 +82,10 @@
#define AV_CPU_FLAG_RVI (1 << 0) ///< I (full GPR bank)
#define AV_CPU_FLAG_RVF (1 << 1) ///< F (single precision FP)
#define AV_CPU_FLAG_RVD (1 << 2) ///< D (double precision FP)
#define AV_CPU_FLAG_RVV_I32 (1 << 3) ///< Vectors of 8/16/32-bit int's */
#define AV_CPU_FLAG_RVV_F32 (1 << 4) ///< Vectors of float's */
#define AV_CPU_FLAG_RVV_I64 (1 << 5) ///< Vectors of 64-bit int's */
#define AV_CPU_FLAG_RVV_F64 (1 << 6) ///< Vectors of double's
/**
* Return the flags which specify extensions supported by the CPU.

19
libavutil/riscv/cpu.c
View File

@@ -40,6 +40,11 @@ int ff_get_cpu_flags_riscv(void)
ret |= AV_CPU_FLAG_RVF;
if (hwcap & HWCAP_RV('D'))
ret |= AV_CPU_FLAG_RVD;
/* The V extension implies all Zve* functional subsets */
if (hwcap & HWCAP_RV('V'))
ret |= AV_CPU_FLAG_RVV_I32 | AV_CPU_FLAG_RVV_I64
| AV_CPU_FLAG_RVV_F32 | AV_CPU_FLAG_RVV_F64;
#endif
#ifdef __riscv_i
@@ -50,6 +55,20 @@ int ff_get_cpu_flags_riscv(void)
#if (__riscv_flen >= 64)
ret |= AV_CPU_FLAG_RVD;
#endif
#endif
/* If RV-V is enabled statically at compile-time, check the details. */
#ifdef __riscv_vectors
ret |= AV_CPU_FLAG_RVV_I32;
#if __riscv_v_elen >= 64
ret |= AV_CPU_FLAG_RVV_I64;
#endif
#if __riscv_v_elen_fp >= 32
ret |= AV_CPU_FLAG_RVV_F32;
#if __riscv_v_elen_fp >= 64
ret |= AV_CPU_FLAG_RVV_F64;
#endif
#endif
#endif
return ret;

4
tests/checkasm/checkasm.c
View File

@@ -236,6 +236,10 @@ static const struct {
{ "RVI", "rvi", AV_CPU_FLAG_RVI },
{ "RVF", "rvf", AV_CPU_FLAG_RVF },
{ "RVD", "rvd", AV_CPU_FLAG_RVD },
{ "RVVi32", "rvv_i32", AV_CPU_FLAG_RVV_I32 },
{ "RVVf32", "rvv_f32", AV_CPU_FLAG_RVV_F32 },
{ "RVVi64", "rvv_i64", AV_CPU_FLAG_RVV_I64 },
{ "RVVf64", "rvv_f64", AV_CPU_FLAG_RVV_F64 },
#elif ARCH_MIPS
{ "MMI", "mmi", AV_CPU_FLAG_MMI },
{ "MSA", "msa", AV_CPU_FLAG_MSA },