From: Frank Chang <frank.ch...@sifive.com>
Update vext_get_vlmax() and MAXSZ() to take fractional LMUL into
calculation for RVV 1.0.
Signed-off-by: Frank Chang <frank.ch...@sifive.com>
---
target/riscv/cpu.h | 44 ++++++++++++++++++-------
target/riscv/insn_trans/trans_rvv.inc.c | 11 ++++++-
2 files changed, 42 insertions(+), 13 deletions(-)
diff --git a/target/riscv/cpu.h b/target/riscv/cpu.h
index 8b5e6429015..78264d6ffc4 100644
--- a/target/riscv/cpu.h
+++ b/target/riscv/cpu.h
@@ -376,18 +376,28 @@ FIELD(TB_FLAGS, SEW, 6, 3)
FIELD(TB_FLAGS, VILL, 11, 1)
/*
- * A simplification for VLMAX
- * = (1 << LMUL) * VLEN / (8 * (1 << SEW))
- * = (VLEN << LMUL) / (8 << SEW)
- * = (VLEN << LMUL) >> (SEW + 3)
- * = VLEN >> (SEW + 3 - LMUL)
+ * Encode LMUL to lmul as following:
+ * LMUL vlmul lmul
+ * 1 000 0
+ * 2 001 1
+ * 4 010 2
+ * 8 011 3
+ * - 100 -
+ * 1/8 101 -3
+ * 1/4 110 -2
+ * 1/2 111 -1
+ *
+ * then, we can calculate VLMAX = vlen >> (vsew + 3 - lmul)
+ * e.g. vlen = 256 bits, SEW = 16, LMUL = 1/8
+ * => VLMAX = vlen >> (1 + 3 - (-3))
+ * = 256 >> 7
+ * = 2
*/
static inline uint32_t vext_get_vlmax(RISCVCPU *cpu, target_ulong vtype)
{
- uint8_t sew, lmul;
-
- sew = FIELD_EX64(vtype, VTYPE, VSEW);
- lmul = FIELD_EX64(vtype, VTYPE, VLMUL);
+ uint8_t sew = FIELD_EX64(vtype, VTYPE, VSEW);
+ uint8_t vlmul = FIELD_EX64(vtype, VTYPE, VLMUL);
+ int8_t lmul = (int8_t)(vlmul << 5) >> 5;
return cpu->cfg.vlen >> (sew + 3 - lmul);
}
@@ -400,12 +410,22 @@ static inline void cpu_get_tb_cpu_state(CPURISCVState
*env, target_ulong *pc,
*cs_base = 0;
if (riscv_has_ext(env, RVV)) {
+ /*
+ * If env->vl equals to VLMAX, we can use generic vector operation
+ * expanders (GVEC) to accerlate the vector operations.
+ * However, as LMUL could be a fractional number. The maximum
+ * vector size can be operated might be less than 8 bytes,
+ * which is not supported by GVEC. So we set vl_eq_vlmax flag to true
+ * only when maxsz >= 8 bytes.
+ */
uint32_t vlmax = vext_get_vlmax(env_archcpu(env), env->vtype);
- bool vl_eq_vlmax = (env->vstart == 0) && (vlmax == env->vl);
+ uint32_t sew = FIELD_EX64(env->vtype, VTYPE, VSEW);
+ uint32_t maxsz = vlmax * (1 << sew);
+ bool vl_eq_vlmax = (env->vstart == 0) && (vlmax == env->vl)
+ && (maxsz >= 8);
flags = FIELD_DP32(flags, TB_FLAGS, VILL,
FIELD_EX64(env->vtype, VTYPE, VILL));
- flags = FIELD_DP32(flags, TB_FLAGS, SEW,
- FIELD_EX64(env->vtype, VTYPE, VSEW));
+ flags = FIELD_DP32(flags, TB_FLAGS, SEW, sew);
flags = FIELD_DP32(flags, TB_FLAGS, LMUL,
FIELD_EX64(env->vtype, VTYPE, VLMUL));
flags = FIELD_DP32(flags, TB_FLAGS, VL_EQ_VLMAX, vl_eq_vlmax);
diff --git a/target/riscv/insn_trans/trans_rvv.inc.c
b/target/riscv/insn_trans/trans_rvv.inc.c
index 725f36fcfcc..82403dff4b9 100644
--- a/target/riscv/insn_trans/trans_rvv.inc.c
+++ b/target/riscv/insn_trans/trans_rvv.inc.c
@@ -1255,7 +1255,16 @@ GEN_VEXT_TRANS(vamomaxuei64_v, 64, 35, rwdvm, amo_op,
amo_check)
/*
*** Vector Integer Arithmetic Instructions
*/
-#define MAXSZ(s) (s->vlen >> (3 - s->lmul))
+
+/*
+ * MAXSZ returns the maximum vector size can be operated in bytes,
+ * which is used in GVEC IR when vl_eq_vlmax flag is set to true
+ * to accerlate vector operation.
+ */
+static inline uint32_t MAXSZ(DisasContext *s)
+{
+ return (s->vlen >> 3) * s->flmul;
+}
static bool opivv_check(DisasContext *s, arg_rmrr *a)
{
--
2.17.1
