On 4/12/24 00:33, Richard Henderson wrote:
Allocate and fill a GString instead of snprintf and
appending to a fixed sized buffer.

Signed-off-by: Richard Henderson <richard.hender...@linaro.org>
---
  disas/riscv.c | 209 ++++++++++++++++++++++----------------------------
  1 file changed, 92 insertions(+), 117 deletions(-)

diff --git a/disas/riscv.c b/disas/riscv.c
index e236c8b5b7..f60f9bda43 100644
--- a/disas/riscv.c
+++ b/disas/riscv.c
@@ -4757,272 +4757,249 @@ static size_t inst_length(rv_inst inst)
/* format instruction */ -static void append(char *s1, const char *s2, size_t n)
-{
-    size_t l1 = strlen(s1);
-    if (n - l1 - 1 > 0) {
-        strncat(s1, s2, n - l1);
-    }
-}
-
-static void format_inst(char *buf, size_t buflen, size_t tab, rv_decode *dec)
+static GString *format_inst(size_t tab, rv_decode *dec)
  {
      const rv_opcode_data *opcode_data = dec->opcode_data;
-    char tmp[64];
+    GString *buf = g_string_sized_new(64);
      const char *fmt;
fmt = opcode_data[dec->op].format;
      while (*fmt) {
          switch (*fmt) {
          case 'O':
-            append(buf, opcode_data[dec->op].name, buflen);
+            g_string_append(buf, opcode_data[dec->op].name);
              break;
          case '(':
-            append(buf, "(", buflen);
-            break;
          case ',':
-            append(buf, ",", buflen);
-            break;
          case ')':
-            append(buf, ")", buflen);
-            break;
          case '-':
-            append(buf, "-", buflen);
+            g_string_append_c(buf, *fmt);
              break;
          case 'b':
-            snprintf(tmp, sizeof(tmp), "%d", dec->bs);
-            append(buf, tmp, buflen);
+            g_string_append_printf(buf, "%d", dec->bs);
              break;
          case 'n':
-            snprintf(tmp, sizeof(tmp), "%d", dec->rnum);
-            append(buf, tmp, buflen);
+            g_string_append_printf(buf, "%d", dec->rnum);
              break;
          case '0':
-            append(buf, rv_ireg_name_sym[dec->rd], buflen);
+            g_string_append(buf, rv_ireg_name_sym[dec->rd]);
              break;
          case '1':
-            append(buf, rv_ireg_name_sym[dec->rs1], buflen);
+            g_string_append(buf, rv_ireg_name_sym[dec->rs1]);
              break;
          case '2':
-            append(buf, rv_ireg_name_sym[dec->rs2], buflen);
+            g_string_append(buf, rv_ireg_name_sym[dec->rs2]);
              break;
          case '3':
-            append(buf, dec->cfg->ext_zfinx ? rv_ireg_name_sym[dec->rd] :
-                                              rv_freg_name_sym[dec->rd],
-                   buflen);
+            if (dec->cfg->ext_zfinx) {
+                g_string_append(buf, rv_ireg_name_sym[dec->rd]);
+            } else {
+                g_string_append(buf, rv_freg_name_sym[dec->rd]);
+            }
              break;
          case '4':
-            append(buf, dec->cfg->ext_zfinx ? rv_ireg_name_sym[dec->rs1] :
-                                              rv_freg_name_sym[dec->rs1],
-                   buflen);
+            if (dec->cfg->ext_zfinx) {
+                g_string_append(buf, rv_ireg_name_sym[dec->rs1]);
+            } else {
+                g_string_append(buf, rv_freg_name_sym[dec->rs1]);
+            }
              break;
          case '5':
-            append(buf, dec->cfg->ext_zfinx ? rv_ireg_name_sym[dec->rs2] :
-                                              rv_freg_name_sym[dec->rs2],
-                   buflen);
+            if (dec->cfg->ext_zfinx) {
+                g_string_append(buf, rv_ireg_name_sym[dec->rs2]);
+            } else {
+                g_string_append(buf, rv_freg_name_sym[dec->rs2]);
+            }
              break;
          case '6':
-            append(buf, dec->cfg->ext_zfinx ? rv_ireg_name_sym[dec->rs3] :
-                                              rv_freg_name_sym[dec->rs3],
-                   buflen);
+            if (dec->cfg->ext_zfinx) {
+                g_string_append(buf, rv_ireg_name_sym[dec->rs3]);
+            } else {
+                g_string_append(buf, rv_freg_name_sym[dec->rs3]);
+            }
              break;
          case '7':
-            snprintf(tmp, sizeof(tmp), "%d", dec->rs1);
-            append(buf, tmp, buflen);
+            g_string_append_printf(buf, "%d", dec->rs1);
              break;
          case 'i':
-            snprintf(tmp, sizeof(tmp), "%d", dec->imm);
-            append(buf, tmp, buflen);
+            g_string_append_printf(buf, "%d", dec->imm);
              break;
          case 'u':
-            snprintf(tmp, sizeof(tmp), "%u", ((uint32_t)dec->imm & 0b111111));
-            append(buf, tmp, buflen);
+            g_string_append_printf(buf, "%u", ((uint32_t)dec->imm & 0b111111));
              break;
          case 'j':
-            snprintf(tmp, sizeof(tmp), "%d", dec->imm1);
-            append(buf, tmp, buflen);
+            g_string_append_printf(buf, "%d", dec->imm1);
              break;
          case 'o':
-            snprintf(tmp, sizeof(tmp), "%d", dec->imm);
-            append(buf, tmp, buflen);
-            while (strlen(buf) < tab * 2) {
-                append(buf, " ", buflen);
+            g_string_append_printf(buf, "%d", dec->imm);
+            while (buf->len < tab * 2) {
+                g_string_append_c(buf, ' ');
              }
-            snprintf(tmp, sizeof(tmp), "# 0x%" PRIx64,
-                dec->pc + dec->imm);
-            append(buf, tmp, buflen);
+            g_string_append_printf(buf, "# 0x%" PRIx64, dec->pc + dec->imm);
              break;
          case 'U':
              fmt++;
-            snprintf(tmp, sizeof(tmp), "%d", dec->imm >> 12);
-            append(buf, tmp, buflen);
+            g_string_append_printf(buf, "%d", dec->imm >> 12);
              if (*fmt == 'o') {
-                while (strlen(buf) < tab * 2) {
-                    append(buf, " ", buflen);
+                while (buf->len < tab * 2) {
+                    g_string_append_c(buf, ' ');
                  }
-                snprintf(tmp, sizeof(tmp), "# 0x%" PRIx64,
-                    dec->pc + dec->imm);
-                append(buf, tmp, buflen);
+                g_string_append_printf(buf, "# 0x%" PRIx64, dec->pc + 
dec->imm);
              }
              break;
          case 'c': {
              const char *name = csr_name(dec->imm & 0xfff);
              if (name) {
-                append(buf, name, buflen);
+                g_string_append(buf, name);
              } else {
-                snprintf(tmp, sizeof(tmp), "0x%03x", dec->imm & 0xfff);
-                append(buf, tmp, buflen);
+                g_string_append_printf(buf, "0x%03x", dec->imm & 0xfff);
              }
              break;
          }
          case 'r':
              switch (dec->rm) {
              case rv_rm_rne:
-                append(buf, "rne", buflen);
+                g_string_append(buf, "rne");
                  break;
              case rv_rm_rtz:
-                append(buf, "rtz", buflen);
+                g_string_append(buf, "rtz");
                  break;
              case rv_rm_rdn:
-                append(buf, "rdn", buflen);
+                g_string_append(buf, "rdn");
                  break;
              case rv_rm_rup:
-                append(buf, "rup", buflen);
+                g_string_append(buf, "rup");
                  break;
              case rv_rm_rmm:
-                append(buf, "rmm", buflen);
+                g_string_append(buf, "rmm");
                  break;
              case rv_rm_dyn:
-                append(buf, "dyn", buflen);
+                g_string_append(buf, "dyn");
                  break;
              default:
-                append(buf, "inv", buflen);
+                g_string_append(buf, "inv");
                  break;
              }
              break;
          case 'p':
              if (dec->pred & rv_fence_i) {
-                append(buf, "i", buflen);
+                g_string_append_c(buf, 'i');
              }
              if (dec->pred & rv_fence_o) {
-                append(buf, "o", buflen);
+                g_string_append_c(buf, 'o');
              }
              if (dec->pred & rv_fence_r) {
-                append(buf, "r", buflen);
+                g_string_append_c(buf, 'r');
              }
              if (dec->pred & rv_fence_w) {
-                append(buf, "w", buflen);
+                g_string_append_c(buf, 'w');
              }
              break;
          case 's':
              if (dec->succ & rv_fence_i) {
-                append(buf, "i", buflen);
+                g_string_append_c(buf, 'i');
              }
              if (dec->succ & rv_fence_o) {
-                append(buf, "o", buflen);
+                g_string_append_c(buf, 'o');
              }
              if (dec->succ & rv_fence_r) {
-                append(buf, "r", buflen);
+                g_string_append_c(buf, 'r');
              }
              if (dec->succ & rv_fence_w) {
-                append(buf, "w", buflen);
+                g_string_append_c(buf, 'w');
              }
              break;
          case '\t':
-            while (strlen(buf) < tab) {
-                append(buf, " ", buflen);
+            while (buf->len < tab) {
+                g_string_append_c(buf, ' ');
              }
              break;
          case 'A':
              if (dec->aq) {
-                append(buf, ".aq", buflen);
+                g_string_append(buf, ".aq");
              }
              break;
          case 'R':
              if (dec->rl) {
-                append(buf, ".rl", buflen);
+                g_string_append(buf, ".rl");
              }
              break;
          case 'l':
-            append(buf, ",v0", buflen);
+            g_string_append(buf, ",v0");
              break;
          case 'm':
              if (dec->vm == 0) {
-                append(buf, ",v0.t", buflen);
+                g_string_append(buf, ",v0.t");
              }
              break;
          case 'D':
-            append(buf, rv_vreg_name_sym[dec->rd], buflen);
+            g_string_append(buf, rv_vreg_name_sym[dec->rd]);
              break;
          case 'E':
-            append(buf, rv_vreg_name_sym[dec->rs1], buflen);
+            g_string_append(buf, rv_vreg_name_sym[dec->rs1]);
              break;
          case 'F':
-            append(buf, rv_vreg_name_sym[dec->rs2], buflen);
+            g_string_append(buf, rv_vreg_name_sym[dec->rs2]);
              break;
          case 'G':
-            append(buf, rv_vreg_name_sym[dec->rs3], buflen);
+            g_string_append(buf, rv_vreg_name_sym[dec->rs3]);
              break;
          case 'v': {
-            char nbuf[32] = {0};
              const int sew = 1 << (((dec->vzimm >> 3) & 0b111) + 3);
-            sprintf(nbuf, "%d", sew);
              const int lmul = dec->vzimm & 0b11;
              const int flmul = (dec->vzimm >> 2) & 1;
              const char *vta = (dec->vzimm >> 6) & 1 ? "ta" : "tu";
              const char *vma = (dec->vzimm >> 7) & 1 ? "ma" : "mu";
-            append(buf, "e", buflen);
-            append(buf, nbuf, buflen);
-            append(buf, ",m", buflen);
+
+            g_string_append_printf(buf, "e%d,m", sew);
              if (flmul) {
                  switch (lmul) {
                  case 3:
-                    sprintf(nbuf, "f2");
+                    g_string_append(buf, "f2");
                      break;
                  case 2:
-                    sprintf(nbuf, "f4");
+                    g_string_append(buf, "f4");
                      break;
                  case 1:
-                    sprintf(nbuf, "f8");
-                break;
+                    g_string_append(buf, "f8");
+                    break;
                  }
-                append(buf, nbuf, buflen);
              } else {
-                sprintf(nbuf, "%d", 1 << lmul);
-                append(buf, nbuf, buflen);
+                g_string_append_printf(buf, "%d", 1 << lmul);
              }
-            append(buf, ",", buflen);
-            append(buf, vta, buflen);
-            append(buf, ",", buflen);
-            append(buf, vma, buflen);
+            g_string_append_c(buf, ',');
+            g_string_append(buf, vta);
+            g_string_append_c(buf, ',');
+            g_string_append(buf, vma);
              break;
          }
          case 'x': {
              switch (dec->rlist) {
              case 4:
-                snprintf(tmp, sizeof(tmp), "{ra}");
+                g_string_append(buf, "{ra}");
                  break;
              case 5:
-                snprintf(tmp, sizeof(tmp), "{ra, s0}");
+                g_string_append(buf, "{ra, s0}");
                  break;
              case 15:
-                snprintf(tmp, sizeof(tmp), "{ra, s0-s11}");
+                g_string_append(buf, "{ra, s0-s11}");
                  break;
              default:
-                snprintf(tmp, sizeof(tmp), "{ra, s0-s%d}", dec->rlist - 5);
+                g_string_append_printf(buf, "{ra, s0-s%d}", dec->rlist - 5);
                  break;
              }
-            append(buf, tmp, buflen);
              break;
          }
          case 'h':
-            append(buf, rv_fli_name_const[dec->imm], buflen);
+            g_string_append(buf, rv_fli_name_const[dec->imm]);
              break;
          default:
              break;
          }
          fmt++;
      }
+
+    return buf;
  }
/* lift instruction to pseudo-instruction */
@@ -5108,9 +5085,8 @@ 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,
-            RISCVCPUConfig *cfg)
+static GString *disasm_inst(rv_isa isa, uint64_t pc, rv_inst inst,
+                            RISCVCPUConfig *cfg)
  {
      rv_decode dec = { 0 };
      dec.pc = pc;
@@ -5157,7 +5133,7 @@ disasm_inst(char *buf, size_t buflen, rv_isa isa, 
uint64_t pc, rv_inst inst,
      decode_inst_operands(&dec, isa);
      decode_inst_decompress(&dec, isa);
      decode_inst_lift_pseudo(&dec);
-    format_inst(buf, buflen, 24, &dec);
+    return format_inst(24, &dec);
  }
#define INST_FMT_2 "%04" PRIx64 " "
@@ -5168,7 +5144,6 @@ disasm_inst(char *buf, size_t buflen, rv_isa isa, 
uint64_t pc, rv_inst inst,
  static int
  print_insn_riscv(bfd_vma memaddr, struct disassemble_info *info, rv_isa isa)
  {
-    char buf[128] = { 0 };
      bfd_byte packet[2];
      rv_inst inst = 0;
      size_t len = 2;
@@ -5209,9 +5184,9 @@ print_insn_riscv(bfd_vma memaddr, struct disassemble_info 
*info, rv_isa isa)
          }
      }
- disasm_inst(buf, sizeof(buf), isa, memaddr, inst,
-                (RISCVCPUConfig *)info->target_info);
-    (*info->fprintf_func)(info->stream, "%s", buf);
+    g_autoptr(GString) str =
+        disasm_inst(isa, memaddr, inst, (RISCVCPUConfig *)info->target_info);
+    (*info->fprintf_func)(info->stream, "%s", str->str);
return len;
  }

Reviewed-by: Pierrick Bouvier <pierrick.bouv...@linaro.org>

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