[RFC v4 12/70] target/riscv: rvv-1.0: add fractional LMUL

[frank . chang]

From: Frank Chang <frank.chang@sifive.com>

Introduce the concepts of fractional LMUL for RVV 1.0.
In RVV 1.0, LMUL bits are contiguous in vtype register.

Signed-off-by: Frank Chang <frank.chang@sifive.com>
---
 target/riscv/cpu.h           | 15 ++++++++-------
 target/riscv/translate.c     | 16 ++++++++++++++--
 target/riscv/vector_helper.c | 16 ++++++++++++++--
 3 files changed, 36 insertions(+), 11 deletions(-)

diff --git a/target/riscv/cpu.h b/target/riscv/cpu.h
index 08d2c10a024..d0f9a76ca01 100644
--- a/target/riscv/cpu.h
+++ b/target/riscv/cpu.h
@@ -94,10 +94,10 @@ typedef struct CPURISCVState CPURISCVState;
 
 #define RV_VLEN_MAX 256
 
-FIELD(VTYPE, VLMUL, 0, 2)
-FIELD(VTYPE, VSEW, 2, 3)
-FIELD(VTYPE, VEDIV, 5, 2)
-FIELD(VTYPE, RESERVED, 7, sizeof(target_ulong) * 8 - 9)
+FIELD(VTYPE, VLMUL, 0, 3)
+FIELD(VTYPE, VSEW, 3, 3)
+FIELD(VTYPE, VEDIV, 8, 2)
+FIELD(VTYPE, RESERVED, 10, sizeof(target_ulong) * 8 - 11)
 FIELD(VTYPE, VILL, sizeof(target_ulong) * 8 - 1, 1)
 
 struct CPURISCVState {
@@ -368,9 +368,10 @@ typedef RISCVCPU ArchCPU;
 #include "exec/cpu-all.h"
 
 FIELD(TB_FLAGS, VL_EQ_VLMAX, 2, 1)
-FIELD(TB_FLAGS, LMUL, 3, 2)
-FIELD(TB_FLAGS, SEW, 5, 3)
-FIELD(TB_FLAGS, VILL, 8, 1)
+FIELD(TB_FLAGS, LMUL, 3, 3)
+FIELD(TB_FLAGS, SEW, 6, 3)
+/* Skip MSTATUS_VS (0x600) fields */
+FIELD(TB_FLAGS, VILL, 11, 1)
 
 /*
  * A simplification for VLMAX
diff --git a/target/riscv/translate.c b/target/riscv/translate.c
index 7b6088677d4..10ef55bbeb7 100644
--- a/target/riscv/translate.c
+++ b/target/riscv/translate.c
@@ -59,7 +59,19 @@ typedef struct DisasContext {
     bool ext_ifencei;
     /* vector extension */
     bool vill;
-    uint8_t lmul;
+    /*
+     * Encode LMUL to lmul as follows:
+     *     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
+     */
+    int8_t lmul;
     uint8_t sew;
     uint16_t vlen;
     bool vl_eq_vlmax;
@@ -851,7 +863,7 @@ static void riscv_tr_init_disas_context(DisasContextBase 
*dcbase, CPUState *cs)
     ctx->vlen = cpu->cfg.vlen;
     ctx->vill = FIELD_EX32(tb_flags, TB_FLAGS, VILL);
     ctx->sew = FIELD_EX32(tb_flags, TB_FLAGS, SEW);
-    ctx->lmul = FIELD_EX32(tb_flags, TB_FLAGS, LMUL);
+    ctx->lmul = sextract32(FIELD_EX32(tb_flags, TB_FLAGS, LMUL), 0, 3);
     ctx->vl_eq_vlmax = FIELD_EX32(tb_flags, TB_FLAGS, VL_EQ_VLMAX);
 }
 
diff --git a/target/riscv/vector_helper.c b/target/riscv/vector_helper.c
index f42346cb9ca..37c510b98f0 100644
--- a/target/riscv/vector_helper.c
+++ b/target/riscv/vector_helper.c
@@ -86,9 +86,21 @@ static inline uint32_t vext_vm(uint32_t desc)
     return FIELD_EX32(simd_data(desc), VDATA, VM);
 }
 
-static inline uint32_t vext_lmul(uint32_t desc)
+/*
+ * 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
+ */
+static inline int32_t vext_lmul(uint32_t desc)
 {
-    return FIELD_EX32(simd_data(desc), VDATA, LMUL);
+    return sextract32(FIELD_EX32(simd_data(desc), VDATA, LMUL), 0, 3);
 }
 
 static uint32_t vext_wd(uint32_t desc)
-- 
2.17.1