String buffers, part 3b: Change IR_BUFHDR op2 mode bits to mode.

Sponsored by fmad.io.

src/lj_asm.c

@@ -1149,24 +1149,30 @@ static void asm_tvptr(ASMState *as, Reg dest, IRRef ref, MSize mode);
 static void asm_bufhdr(ASMState *as, IRIns *ir)
 {
   Reg sb = ra_dest(as, ir, RSET_GPR);
-  if ((ir->op2 & IRBUFHDR_APPEND)) {
+  switch (ir->op2) {
+  case IRBUFHDR_RESET: {
+    Reg tmp = ra_scratch(as, rset_exclude(RSET_GPR, sb));
+    IRIns irbp;
+    irbp.ot = IRT(0, IRT_PTR);  /* Buffer data pointer type. */
+    emit_storeofs(as, &irbp, tmp, sb, offsetof(SBuf, w));
+    emit_loadofs(as, &irbp, tmp, sb, offsetof(SBuf, b));
+    break;
+    }
+  case IRBUFHDR_APPEND: {
     /* Rematerialize const buffer pointer instead of likely spill. */
     IRIns *irp = IR(ir->op1);
     if (!(ra_hasreg(irp->r) || irp == ir-1 ||
 	  (irp == ir-2 && !ra_used(ir-1)))) {
-      while (!(irp->o == IR_BUFHDR && !(irp->op2 & IRBUFHDR_APPEND)))
+      while (!(irp->o == IR_BUFHDR && irp->op2 == IRBUFHDR_RESET))
 	irp = IR(irp->op1);
       if (irref_isk(irp->op1)) {
 	ra_weak(as, ra_allocref(as, ir->op1, RSET_GPR));
 	ir = irp;
       }
     }
-  } else {
-    Reg tmp = ra_scratch(as, rset_exclude(RSET_GPR, sb));
-    IRIns irbp;
-    irbp.ot = IRT(0, IRT_PTR);  /* Buffer data pointer type. */
-    emit_storeofs(as, &irbp, tmp, sb, offsetof(SBuf, w));
-    emit_loadofs(as, &irbp, tmp, sb, offsetof(SBuf, b));
+    break;
+    }
+  default: lj_assertA(0, "bad BUFHDR op2 %d", ir->op2); break;
   }
 #if LJ_TARGET_X86ORX64
   ra_left(as, sb, ir->op1);

src/lj_opt_fold.c

@@ -586,11 +586,11 @@ LJFOLDF(bufput_append)
 {
   /* New buffer, no other buffer op inbetween and same buffer? */
   if ((J->flags & JIT_F_OPT_FWD) &&
-      !(fleft->op2 & IRBUFHDR_APPEND) &&
+      fleft->op2 == IRBUFHDR_RESET &&
       fleft->prev == fright->op2 &&
       fleft->op1 == IR(fright->op2)->op1) {
     IRRef ref = fins->op1;
-    IR(ref)->op2 = (fleft->op2 | IRBUFHDR_APPEND);  /* Modify BUFHDR. */
+    IR(ref)->op2 = IRBUFHDR_APPEND;  /* Modify BUFHDR. */
     IR(ref)->op1 = fright->op1;
     return ref;
   }
@@ -626,14 +626,14 @@ LJFOLDF(bufstr_kfold_cse)
 	     "bad buffer constructor IR op %d", fleft->o);
   if (LJ_LIKELY(J->flags & JIT_F_OPT_FOLD)) {
     if (fleft->o == IR_BUFHDR) {  /* No put operations? */
-      if (!(fleft->op2 & IRBUFHDR_APPEND))  /* Empty buffer? */
+      if (fleft->op2 == IRBUFHDR_RESET)  /* Empty buffer? */
 	return lj_ir_kstr(J, &J2G(J)->strempty);
       fins->op1 = fleft->op1;
       fins->op2 = fleft->prev;  /* Relies on checks in bufput_append. */
       return CSEFOLD;
     } else if (fleft->o == IR_BUFPUT) {
       IRIns *irb = IR(fleft->op1);
-      if (irb->o == IR_BUFHDR && !(irb->op2 & IRBUFHDR_APPEND))
+      if (irb->o == IR_BUFHDR && irb->op2 == IRBUFHDR_RESET)
 	return fleft->op2;  /* Shortcut for a single put operation. */
     }
   }
@@ -646,7 +646,7 @@ LJFOLDF(bufstr_kfold_cse)
 	lj_assertJ(ira->o == IR_BUFHDR || ira->o == IR_BUFPUT ||
 		   ira->o == IR_CALLL || ira->o == IR_CARG,
 		   "bad buffer constructor IR op %d", ira->o);
-	if (ira->o == IR_BUFHDR && !(ira->op2 & IRBUFHDR_APPEND))
+	if (ira->o == IR_BUFHDR && ira->op2 == IRBUFHDR_RESET)
 	  return ref;  /* CSE succeeded. */
 	if (ira->o == IR_CALLL && ira->op2 == IRCALL_lj_buf_puttab)
 	  break;