10 files changed, 47 insertions, 20 deletions
diff --git a/src/jit/dump.lua b/src/jit/dump.lua
index c025a239..2a7d64e4 100644
--- a/src/jit/dump.lua
+++ b/src/jit/dump.lua
@@ -279,6 +279,7 @@ local litname = {
  ["FREF  "] = vmdef.irfield,
  ["FPMATH"] = vmdef.irfpm,
  ["BUFHDR"] = { [0] = "RESET", "APPEND" },
+  ["TOSTR "] = { [0] = "INT", "NUM", "CHAR" },
 }
 local function ctlsub(c)
diff --git a/src/lj_asm.c b/src/lj_asm.c
index e847b8c9..6ff32940 100644
--- a/src/lj_asm.c
+++ b/src/lj_asm.c
@@ -1070,23 +1070,26 @@ static void asm_bufput(ASMState *as, IRIns *ir)
    GCstr *s = ir_kstr(irs);
    if (s->len == 1) {  /* Optimize put of single-char string constant. */
      kchar = strdata(s)[0];
-      ci = &lj_ir_callinfo[IRCALL_lj_buf_putchar];
      args[1] = ASMREF_TMP1;  /* int, truncated to char */
+      ci = &lj_ir_callinfo[IRCALL_lj_buf_putchar];
    }
  } else if (mayfuse(as, ir->op2) && ra_noreg(irs->r)) {
    if (irs->o == IR_TOSTR) {  /* Fuse number to string conversions. */
-      if (LJ_SOFTFP ? (irs+1)->o == IR_HIOP : irt_isnum(IR(irs->op1)->t)) {
+      if (irs->op2 == IRTOSTR_NUM) {
-        ci = &lj_ir_callinfo[IRCALL_lj_buf_putnum];
        args[1] = ASMREF_TMP1;  /* TValue * */
+        ci = &lj_ir_callinfo[IRCALL_lj_buf_putnum];
      } else {
        lua_assert(irt_isinteger(IR(irs->op1)->t));
-        ci = &lj_ir_callinfo[IRCALL_lj_buf_putint];
        args[1] = irs->op1;  /* int */
+        if (irs->op2 == IRTOSTR_INT)
+          ci = &lj_ir_callinfo[IRCALL_lj_buf_putint];
+        else
+          ci = &lj_ir_callinfo[IRCALL_lj_buf_putchar];
      }
    } else if (irs->o == IR_SNEW) {  /* Fuse string allocation. */
-      ci = &lj_ir_callinfo[IRCALL_lj_buf_putmem];
      args[1] = irs->op1;  /* const void * */
      args[2] = irs->op2;  /* MSize */
+      ci = &lj_ir_callinfo[IRCALL_lj_buf_putmem];
    }
  }
  asm_setupresult(as, ir, ci);  /* SBuf * */
@@ -1114,21 +1117,24 @@ static void asm_bufstr(ASMState *as, IRIns *ir)
 static void asm_tostr(ASMState *as, IRIns *ir)
 {
+  const CCallInfo *ci;
  IRRef args[2];
  args[0] = ASMREF_L;
  as->gcsteps++;
-  if (irt_isnum(IR(ir->op1)->t) || (LJ_SOFTFP && (ir+1)->o == IR_HIOP)) {
+  if (ir->op2 == IRTOSTR_NUM) {
-    const CCallInfo *ci = &lj_ir_callinfo[IRCALL_lj_str_fromnum];
    args[1] = ASMREF_TMP1;  /* const lua_Number * */
-    asm_setupresult(as, ir, ci);  /* GCstr * */
+    ci = &lj_ir_callinfo[IRCALL_lj_str_fromnum];
-    asm_gencall(as, ci, args);
-    asm_tvptr(as, ra_releasetmp(as, ASMREF_TMP1), ir->op1);
  } else {
-    const CCallInfo *ci = &lj_ir_callinfo[IRCALL_lj_str_fromint];
    args[1] = ir->op1;  /* int32_t k */
-    asm_setupresult(as, ir, ci);  /* GCstr * */
+    if (ir->op2 == IRTOSTR_INT)
-    asm_gencall(as, ci, args);
+      ci = &lj_ir_callinfo[IRCALL_lj_str_fromint];
+    else
+      ci = &lj_ir_callinfo[IRCALL_lj_str_fromchar];
  }
+  asm_setupresult(as, ir, ci);  /* GCstr * */
+  asm_gencall(as, ci, args);
+  if (ir->op2 == IRTOSTR_NUM)
+    asm_tvptr(as, ra_releasetmp(as, ASMREF_TMP1), ir->op1);
 }
 #if LJ_32 && LJ_HASFFI && !LJ_SOFTFP && !LJ_TARGET_X86
diff --git a/src/lj_ffrecord.c b/src/lj_ffrecord.c
index 32346d22..929dbb55 100644
--- a/src/lj_ffrecord.c
+++ b/src/lj_ffrecord.c
@@ -335,7 +335,8 @@ static void LJ_FASTCALL recff_tostring(jit_State *J, RecordFFData *rd)
    /* Pass on result in J->base[0]. */
  } else if (!recff_metacall(J, rd, MM_tostring)) {
    if (tref_isnumber(tr)) {
-      J->base[0] = emitir(IRT(IR_TOSTR, IRT_STR), tr, 0);
+      J->base[0] = emitir(IRT(IR_TOSTR, IRT_STR), tr,
+                          tref_isnum(tr) ? IRTOSTR_NUM : IRTOSTR_INT);
    } else if (tref_ispri(tr)) {
      J->base[0] = lj_ir_kstr(J, strV(&J->fn->c.upvalue[tref_type(tr)]));
    } else {
diff --git a/src/lj_ir.c b/src/lj_ir.c
index f1e1959f..0ac9d0e6 100644
--- a/src/lj_ir.c
+++ b/src/lj_ir.c
@@ -444,7 +444,8 @@ TRef LJ_FASTCALL lj_ir_tostr(jit_State *J, TRef tr)
  if (!tref_isstr(tr)) {
    if (!tref_isnumber(tr))
      lj_trace_err(J, LJ_TRERR_BADTYPE);
-    tr = emitir(IRT(IR_TOSTR, IRT_STR), tr, 0);
+    tr = emitir(IRT(IR_TOSTR, IRT_STR), tr,
+                tref_isnum(tr) ? IRTOSTR_NUM : IRTOSTR_INT);
  }
  return tr;
 }
diff --git a/src/lj_ir.h b/src/lj_ir.h
index 0cbd8b55..7ab8ab12 100644
--- a/src/lj_ir.h
+++ b/src/lj_ir.h
@@ -133,7 +133,7 @@
  /* Type conversions. */ \
  _(CONV,       NW, ref, lit) \
  _(TOBIT,      N , ref, ref) \
-  _(TOSTR,      N , ref, ___) \
+  _(TOSTR,      N , ref, lit) \
  _(STRTO,      N , ref, ___) \
  \
  /* Calls. */ \
@@ -246,6 +246,11 @@ IRFLDEF(FLENUM)
 #define IRCONV_INDEX  (2<<IRCONV_CSH)   /* Check + special backprop rules. */
 #define IRCONV_CHECK  (3<<IRCONV_CSH)   /* Number checked for integerness. */
+/* TOSTR mode, stored in op2. */
+#define IRTOSTR_INT             0       /* Convert integer to string. */
+#define IRTOSTR_NUM             1       /* Convert number to string. */
+#define IRTOSTR_CHAR            2       /* Convert char value to string. */
 /* -- IR operands --------------------------------------------------------- */
 /* IR operand mode (2 bit). */
diff --git a/src/lj_ircall.h b/src/lj_ircall.h
index 46bb54fe..456f89ac 100644
--- a/src/lj_ircall.h
+++ b/src/lj_ircall.h
@@ -105,6 +105,7 @@ typedef struct CCallInfo {
  _(ANY,        lj_strscan_num,         2,  FN, INT, 0) \
  _(ANY,        lj_str_fromint,         2,  FN, STR, CCI_L) \
  _(ANY,        lj_str_fromnum,         2,  FN, STR, CCI_L) \
+  _(ANY,        lj_str_fromchar,        2,  FN, STR, CCI_L) \
  _(ANY,        lj_buf_putmem,          3,   S, P32, 0) \
  _(ANY,        lj_buf_putstr,          2,  FS, P32, 0) \
  _(ANY,        lj_buf_putchar,         2,  FS, P32, 0) \
diff --git a/src/lj_opt_fold.c b/src/lj_opt_fold.c
index e3194f76..06e0e783 100644
--- a/src/lj_opt_fold.c
+++ b/src/lj_opt_fold.c
@@ -759,16 +759,18 @@ LJFOLDF(kfold_conv_knum_u64_num)
  return INT64FOLD(lj_num2u64(knumleft));
 }
-LJFOLD(TOSTR KNUM)
+LJFOLD(TOSTR KNUM any)
 LJFOLDF(kfold_tostr_knum)
 {
  return lj_ir_kstr(J, lj_str_fromnum(J->L, &knumleft));
 }
-LJFOLD(TOSTR KINT)
+LJFOLD(TOSTR KINT any)
 LJFOLDF(kfold_tostr_kint)
 {
-  return lj_ir_kstr(J, lj_str_fromint(J->L, fleft->i));
+  return lj_ir_kstr(J, fins->op2 == IRTOSTR_INT ?
+                       lj_str_fromint(J->L, fleft->i) :
+                       lj_str_fromchar(J->L, fleft->i));
 }
 LJFOLD(STRTO KGC)
diff --git a/src/lj_record.c b/src/lj_record.c
index bafb6ff7..1beaa75f 100644
--- a/src/lj_record.c
+++ b/src/lj_record.c
@@ -1611,7 +1611,8 @@ static TRef rec_cat(jit_State *J, BCReg baseslot, BCReg topslot)
    /* First convert numbers to strings. */
    for (trp = top; trp >= base; trp--) {
      if (tref_isnumber(*trp))
-        *trp = emitir(IRT(IR_TOSTR, IRT_STR), *trp, 0);
+        *trp = emitir(IRT(IR_TOSTR, IRT_STR), *trp,
+                      tref_isnum(*trp) ? IRTOSTR_NUM : IRTOSTR_INT);
      else if (!tref_isstr(*trp))
        break;
    }
diff --git a/src/lj_str.c b/src/lj_str.c
index a0080e31..675213d7 100644
--- a/src/lj_str.c
+++ b/src/lj_str.c
@@ -274,6 +274,14 @@ GCstr * LJ_FASTCALL lj_str_fromnumber(lua_State *L, cTValue *o)
  return tvisint(o) ? lj_str_fromint(L, intV(o)) : lj_str_fromnum(L, &o->n);
 }
+/* Convert char value to string. */
+GCstr * LJ_FASTCALL lj_str_fromchar(lua_State *L, int c)
+{
+  char buf[1];
+  buf[0] = c;
+  return lj_str_new(L, buf, 1);
+}
 /* -- String formatting --------------------------------------------------- */
 /* Push formatted message as a string object to Lua stack. va_list variant. */
diff --git a/src/lj_str.h b/src/lj_str.h
index 61666a2a..bf508d3b 100644
--- a/src/lj_str.h
+++ b/src/lj_str.h
@@ -27,6 +27,7 @@ LJ_FUNC const char *lj_str_buftv(char *buf, cTValue *o, MSize *lenp);
 LJ_FUNCA GCstr * LJ_FASTCALL lj_str_fromnum(lua_State *L, const lua_Number *np);
 LJ_FUNC GCstr * LJ_FASTCALL lj_str_fromint(lua_State *L, int32_t k);
 LJ_FUNCA GCstr * LJ_FASTCALL lj_str_fromnumber(lua_State *L, cTValue *o);
+LJ_FUNC GCstr * LJ_FASTCALL lj_str_fromchar(lua_State *L, int c);
 #define LJ_STR_INTBUF           (1+10)
 #define LJ_STR_NUMBUF           LUAI_MAXNUMBER2STR