[PATCH v2 03/12] target/riscv: Add vext_check_input_eew to check mismatched input EEWs encoding constraint

[Max Chou]

According to the v spec, a vector register cannot be used to provide source
operands with more than one EEW for a single instruction.

Signed-off-by: Max Chou <max.c...@sifive.com>
---
 target/riscv/insn_trans/trans_rvv.c.inc | 29 +++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

diff --git a/target/riscv/insn_trans/trans_rvv.c.inc 
b/target/riscv/insn_trans/trans_rvv.c.inc
index e630f8661e1..70c19c49ae4 100644
--- a/target/riscv/insn_trans/trans_rvv.c.inc
+++ b/target/riscv/insn_trans/trans_rvv.c.inc
@@ -379,6 +379,35 @@ static bool vext_check_ld_index(DisasContext *s, int vd, 
int vs2,
     return ret;
 }
 
+/*
+ * Check whether a vector register is used to provide source operands with
+ * more than one EEW for the vector instruction.
+ * Returns true if the instruction has valid encoding
+ * Returns false if encoding violates the mismatched input EEWs constraint
+ */
+static bool vext_check_input_eew(DisasContext *s, int vs1, uint8_t eew_vs1,
+                                 int vs2, uint8_t eew_vs2, int vm)
+{
+    bool is_valid = true;
+    int8_t emul_vs1 = eew_vs1 - s->sew + s->lmul;
+    int8_t emul_vs2 = eew_vs2 - s->sew + s->lmul;
+
+    /* When vm is 0, vs1 & vs2(EEW!=1) group can't overlap v0 (EEW=1) */
+    if ((vs1 != -1 && !require_vm(vm, vs1)) ||
+        (vs2 != -1 && !require_vm(vm, vs2))) {
+        is_valid = false;
+    }
+
+    /* When eew_vs1 != eew_vs2, check whether vs1 and vs2 are overlapped */
+    if ((vs1 != -1 && vs2 != -1) && (eew_vs1 != eew_vs2) &&
+        is_overlapped(vs1, 1 << MAX(emul_vs1, 0),
+                      vs2, 1 << MAX(emul_vs2, 0))) {
+        is_valid = false;
+    }
+
+    return is_valid;
+}
+
 static bool vext_check_ss(DisasContext *s, int vd, int vs, int vm)
 {
     return require_vm(vm, vd) &&
-- 
2.43.0