[PATCH 7/9] disas/riscv: Provide infrastructure for vendor extensions

[Christoph Muellner]

From: Christoph Müllner <christoph.muellner@vrull.eu>

A previous patch provides a pointer to the RISCVCPUConfig data.
Let's use this to add the necessary code for vendor extensions.
This patch does not change the current behaviour, but clearly
defines how vendor extension support can be added to the disassembler.

Signed-off-by: Christoph Müllner <christoph.muellner@vrull.eu>
---
 disas/riscv.c | 34 ++++++++++++++++++++++++++++++----
 1 file changed, 30 insertions(+), 4 deletions(-)

diff --git a/disas/riscv.c b/disas/riscv.c
index 086edee6a2..db98e3ea6a 100644
--- a/disas/riscv.c
+++ b/disas/riscv.c
@@ -20,6 +20,7 @@
 #include "qemu/osdep.h"
 #include "disas/dis-asm.h"
 #include "disas/riscv.h"
+#include "target/riscv/cpu-config.h"
 
 typedef enum {
     /* 0 is reserved for rv_op_illegal. */
@@ -4599,13 +4600,38 @@ static void decode_inst_decompress(rv_decode *dec, 
rv_isa isa)
 /* disassemble instruction */
 
 static void
-disasm_inst(char *buf, size_t buflen, rv_isa isa, uint64_t pc, rv_inst inst)
+disasm_inst(char *buf, size_t buflen, rv_isa isa, uint64_t pc, rv_inst inst,
+            struct disassemble_info *info)
 {
+    RISCVCPUConfig *cfg = info->private_data;
     rv_decode dec = { 0 };
     dec.pc = pc;
     dec.inst = inst;
-    dec.opcode_data = rvi_opcode_data;
-    decode_inst_opcode(&dec, isa);
+
+    static const struct {
+        bool (*guard_func)(const RISCVCPUConfig *);
+        const rv_opcode_data *opcode_data;
+        void (*decode_func)(rv_decode *, rv_isa);
+    } decoders[] = {
+        { always_true_p, rvi_opcode_data, decode_inst_opcode },
+    };
+
+    for (size_t i = 0; i < ARRAY_SIZE(decoders); i++) {
+        bool (*guard_func)(const RISCVCPUConfig *) = decoders[i].guard_func;
+        const rv_opcode_data *opcode_data = decoders[i].opcode_data;
+        void (*decode_func)(rv_decode *, rv_isa) = decoders[i].decode_func;
+
+        if (guard_func(cfg)) {
+            dec.opcode_data = opcode_data;
+            decode_func(&dec, isa);
+            if (dec.op != rv_op_illegal)
+                break;
+        }
+    }
+
+    if (dec.op == rv_op_illegal)
+        dec.opcode_data = rvi_opcode_data;
+
     decode_inst_operands(&dec, isa);
     decode_inst_decompress(&dec, isa);
     decode_inst_lift_pseudo(&dec);
@@ -4659,7 +4685,7 @@ print_insn_riscv(bfd_vma memaddr, struct disassemble_info 
*info, rv_isa isa)
         break;
     }
 
-    disasm_inst(buf, sizeof(buf), isa, memaddr, inst);
+    disasm_inst(buf, sizeof(buf), isa, memaddr, inst, info);
     (*info->fprintf_func)(info->stream, "%s", buf);
 
     return len;
-- 
2.40.1