FFI: Fix compiled ffi.string() semantics.

5 files changed, 8 insertions, 5 deletions

diff --git a/src/lj_api.c b/src/lj_api.c
index f33748ce..10f9f3cb 100644
--- a/src/lj_api.c
+++ b/src/lj_api.c
@@ -713,7 +713,7 @@ LUA_API void lua_concat(lua_State *L, int n)
       copyTV(L, L->top-1, L->top);
     } while (--n > 0);
   } else if (n == 0) {  /* Push empty string. */
-    setstrV(L, L->top, lj_str_new(L, "", 0));
+    setstrV(L, L->top, &G(L)->strempty);
     incr_top(L);
   }
   /* else n == 1: nothing to do. */
diff --git a/src/lj_asm.c b/src/lj_asm.c
index c349c990..17cbd848 100644
--- a/src/lj_asm.c
+++ b/src/lj_asm.c
@@ -4098,7 +4098,7 @@ static void asm_ir(ASMState *as, IRIns *ir)
   case IR_FSTORE: case IR_XSTORE: asm_fxstore(as, ir); break;
 
   /* Allocations. */
-  case IR_SNEW: asm_snew(as, ir); break;
+  case IR_SNEW: case IR_XSNEW: asm_snew(as, ir); break;
   case IR_TNEW: asm_tnew(as, ir); break;
   case IR_TDUP: asm_tdup(as, ir); break;
   case IR_CNEW: case IR_CNEWI: asm_cnew(as, ir); break;
diff --git a/src/lj_crecord.c b/src/lj_crecord.c
index 5e058a6f..d689b81b 100644
--- a/src/lj_crecord.c
+++ b/src/lj_crecord.c
@@ -970,7 +970,7 @@ void LJ_FASTCALL recff_ffi_string(jit_State *J, RecordFFData *rd)
       tr = crec_ct_tv(J, ctype_get(cts, CTID_P_CCHAR), 0, tr, &rd->argv[0]);
       trlen = lj_ir_call(J, IRCALL_strlen, tr);
     }
-    J->base[0] = emitir(IRT(IR_SNEW, IRT_STR), tr, trlen);
+    J->base[0] = emitir(IRT(IR_XSNEW, IRT_STR), tr, trlen);
   }  /* else: interpreter will throw. */
 }
 
diff --git a/src/lj_ir.h b/src/lj_ir.h
index f9ca4627..4813f250 100644
--- a/src/lj_ir.h
+++ b/src/lj_ir.h
@@ -110,6 +110,7 @@
   \
   /* Allocations. */ \
   _(SNEW,       N , ref, ref)  /* CSE is ok, not marked as A. */ \
+  _(XSNEW,      A , ref, ref) \
   _(TNEW,       AW, lit, lit) \
   _(TDUP,       AW, ref, ___) \
   _(CNEW,       AW, ref, ref) \
diff --git a/src/lj_opt_fold.c b/src/lj_opt_fold.c
index e5ed7ade..e7a1ca54 100644
--- a/src/lj_opt_fold.c
+++ b/src/lj_opt_fold.c
@@ -153,7 +153,8 @@ typedef IRRef (LJ_FASTCALL *FoldFunc)(jit_State *J);
 */
 #define gcstep_barrier(J, ref) \
   ((ref) < J->chain[IR_LOOP] && \
-   (J->chain[IR_SNEW] || J->chain[IR_TNEW] || J->chain[IR_TDUP] || \
+   (J->chain[IR_SNEW] || J->chain[IR_XSNEW] || \
+    J->chain[IR_TNEW] || J->chain[IR_TDUP] || \
     J->chain[IR_CNEW] || J->chain[IR_CNEWI] || J->chain[IR_TOSTR]))
 
 /* -- Constant folding for FP numbers ------------------------------------- */
@@ -445,7 +446,7 @@ LJFOLD(SNEW any KINT)
 LJFOLDF(kfold_snew_empty)
 {
   if (fright->i == 0)
-    return lj_ir_kstr(J, lj_str_new(J->L, "", 0));
+    return lj_ir_kstr(J, &J2G(J)->strempty);
   return NEXTFOLD;
 }
 
@@ -1900,6 +1901,7 @@ LJFOLD(RETF any any)  /* Modifies BASE. */
 LJFOLD(TNEW any any)
 LJFOLD(TDUP any)
 LJFOLD(CNEW any any)
+LJFOLD(XSNEW any any)
 LJFOLDX(lj_ir_emit)
 
 /* ------------------------------------------------------------------------ */