[FFmpeg-devel] [PATCH 2/6] lavu/cpu: CPU flags for the RISC-V Vector extension
remi at remlab.net
remi at remlab.net
Sat Sep 17 15:45:33 EEST 2022
From: Rémi Denis-Courmont <remi at remlab.net>
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 (ZVE32X), floats (ZV32F),
64-bit ints (ZV64X) and doubles (ZVE64D).
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.
---
libavutil/cpu.c | 4 ++++
libavutil/cpu.h | 4 ++++
libavutil/riscv/cpu.c | 46 ++++++++++++++++++++++++++++++++++++++-
tests/checkasm/checkasm.c | 10 ++++++---
4 files changed, 60 insertions(+), 4 deletions(-)
diff --git a/libavutil/cpu.c b/libavutil/cpu.c
index 78e92a1bf6..58ae4858b4 100644
--- a/libavutil/cpu.c
+++ b/libavutil/cpu.c
@@ -187,6 +187,10 @@ 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" },
+ { "rvve32", NULL, 0, AV_OPT_TYPE_CONST, { .i64 = AV_CPU_FLAG_RV_ZVE32X}, .unit = "flags" },
+ { "rvvf", NULL, 0, AV_OPT_TYPE_CONST, { .i64 = AV_CPU_FLAG_RV_ZVE32F}, .unit = "flags" },
+ { "rvve64", NULL, 0, AV_OPT_TYPE_CONST, { .i64 = AV_CPU_FLAG_RV_ZVE64X}, .unit = "flags" },
+ { "rvv", NULL, 0, AV_OPT_TYPE_CONST, { .i64 = AV_CPU_FLAG_RV_ZVE64D}, .unit = "flags" },
#endif
{ NULL },
};
diff --git a/libavutil/cpu.h b/libavutil/cpu.h
index 9aae2ccc7a..00698e30ef 100644
--- a/libavutil/cpu.h
+++ b/libavutil/cpu.h
@@ -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_RV_ZVE32X (1 << 3) ///< Vectors of 8/16/32-bit int's */
+#define AV_CPU_FLAG_RV_ZVE32F (1 << 4) ///< Vectors of float's */
+#define AV_CPU_FLAG_RV_ZVE64X (1 << 5) ///< Vectors of 64-bit int's */
+#define AV_CPU_FLAG_RV_ZVE64D (1 << 6) ///< Vectors of double's
/**
* Return the flags which specify extensions supported by the CPU.
diff --git a/libavutil/riscv/cpu.c b/libavutil/riscv/cpu.c
index b382e8fa07..3e6c99819b 100644
--- a/libavutil/riscv/cpu.c
+++ b/libavutil/riscv/cpu.c
@@ -28,7 +28,32 @@
int ff_force_cpu_flags_riscv(int flags)
{
- if ((flags & AV_CPU_FLAG_RVD) && !(flags & AV_CPU_FLAG_RVF)) {
+ if ((flags & AV_CPU_FLAG_RV_ZVE64D) && !(flags & AV_CPU_FLAG_RV_ZVE64X)) {
+ av_log(NULL, AV_LOG_WARNING, "RV%s implied by specified flags\n",
+ "_ZVE64X");
+ flags |= AV_CPU_FLAG_RV_ZVE64X;
+ }
+
+ if ((flags & AV_CPU_FLAG_RV_ZVE64D) && !(flags & AV_CPU_FLAG_RV_ZVE32F)) {
+ av_log(NULL, AV_LOG_WARNING, "RV%s implied by specified flags\n",
+ "_ZVE32F");
+ flags |= AV_CPU_FLAG_RV_ZVE32F;
+ }
+
+ if ((flags & (AV_CPU_FLAG_RV_ZVE64X | AV_CPU_FLAG_RV_ZVE32F))
+ && !(flags & AV_CPU_FLAG_RV_ZVE32X)) {
+ av_log(NULL, AV_LOG_WARNING, "RV%s implied by specified flags\n",
+ "_ZVE32X");
+ flags |= AV_CPU_FLAG_RV_ZVE32X;
+ }
+
+ if ((flags & AV_CPU_FLAG_RV_ZVE64D) && !(flags & AV_CPU_FLAG_RVD)) {
+ av_log(NULL, AV_LOG_WARNING, "RV%s implied by specified flags\n", "D");
+ flags |= AV_CPU_FLAG_RVD;
+ }
+
+ if ((flags & (AV_CPU_FLAG_RVD | AV_CPU_FLAG_RV_ZVE32F))
+ && !(flags & AV_CPU_FLAG_RVF)) {
av_log(NULL, AV_LOG_WARNING, "RV%s implied by specified flags\n", "F");
flags |= AV_CPU_FLAG_RVF;
}
@@ -48,6 +73,11 @@ 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_RV_ZVE32X | AV_CPU_FLAG_RV_ZVE64X
+ | AV_CPU_FLAG_RV_ZVE32F | AV_CPU_FLAG_RV_ZVE64D;
#endif
#ifdef __riscv_i
@@ -58,6 +88,20 @@ 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_RV_ZVE32X;
+#if __riscv_v_elen >= 64
+ ret |= AV_CPU_FLAG_RV_ZVE64X;
+#endif
+#if __riscv_v_elen_fp >= 32
+ ret |= AV_CPU_FLAG_RV_ZVE32F;
+#if __riscv_v_elen_fp >= 64
+ ret |= AV_CPU_FLAG_RV_ZVE64F;
+#endif
+#endif
#endif
return ret;
diff --git a/tests/checkasm/checkasm.c b/tests/checkasm/checkasm.c
index ea25fbad75..2f863c9a8a 100644
--- a/tests/checkasm/checkasm.c
+++ b/tests/checkasm/checkasm.c
@@ -227,9 +227,13 @@ static const struct {
{ "VSX", "vsx", AV_CPU_FLAG_VSX },
{ "POWER8", "power8", AV_CPU_FLAG_POWER8 },
#elif ARCH_RISCV
- { "RVI", "rvi", AV_CPU_FLAG_RVI },
- { "RVF", "rvf", AV_CPU_FLAG_RVF },
- { "RVD", "rvd", AV_CPU_FLAG_RVD },
+ { "RVI", "rvi", AV_CPU_FLAG_RVI },
+ { "RVF", "rvf", AV_CPU_FLAG_RVF },
+ { "RVD", "rvd", AV_CPU_FLAG_RVD },
+ { "RV_Zve32x", "rv_zve32x", AV_CPU_FLAG_RV_ZVE32X },
+ { "RV_Zve32f", "rv_zve32f", AV_CPU_FLAG_RV_ZVE32F },
+ { "RV_Zve64x", "rv_zve64x", AV_CPU_FLAG_RV_ZVE64X },
+ { "RV_Zve64d", "rv_zve64d", AV_CPU_FLAG_RV_ZVE64D },
#elif ARCH_MIPS
{ "MMI", "mmi", AV_CPU_FLAG_MMI },
{ "MSA", "msa", AV_CPU_FLAG_MSA },
--
2.37.2
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