Fix more issues reported in GH-15852

* Fix incorrect register allocation

* Avoid IR binding/spilling conflict

* Add missing type guard

Author: dstogov

ext/opcache/jit/zend_jit_ir.c

@@ -1298,6 +1298,14 @@ static bool zend_jit_spilling_may_cause_conflict(zend_jit_ctx *jit, int var, ir_
 		 && EX_VAR_TO_NUM(jit->ctx.ir_base[jit->ctx.ir_base[jit->ctx.ir_base[val].op2].op2].val.addr) < jit->current_op_array->last_var) {
 			/* binding between different CVs may cause spill conflict */
 			return 1;
+		} else if (jit->ssa->vars[var].definition >= 0
+		 && jit->ssa->ops[jit->ssa->vars[var].definition].op1_def == var
+		 && jit->ssa->ops[jit->ssa->vars[var].definition].op1_use >= 0
+		 && jit->ssa->vars[jit->ssa->ops[jit->ssa->vars[var].definition].op1_use].no_val
+		 && jit->ssa->vars[jit->ssa->ops[jit->ssa->vars[var].definition].op1_use].definition_phi
+		 && (jit->ssa->cfg.blocks[jit->ssa->vars[jit->ssa->ops[jit->ssa->vars[var].definition].op1_use].definition_phi->block].flags & ZEND_BB_LOOP_HEADER)) {
+			/* Avoid moving spill store out of loop */
+			return 1;
 		}
 		return 0;
 	}

ext/opcache/jit/zend_jit_trace.c

@@ -3295,9 +3295,7 @@ static zend_jit_reg_var* zend_jit_trace_allocate_registers(zend_jit_trace_rec *t
 							RA_REG_FLAGS(def) |= ZREG_LOAD;
 						}
 					}
-				} else if (RA_HAS_REG(use)
-						&& (!ssa->vars[def].no_val
-				)) {
+				} else if (RA_HAS_REG(use)) {
 					if (ssa->vars[use].use_chain >= 0) {
 						RA_REG_FLAGS(use) |= ZREG_STORE; // TODO: ext/opcache/tests/jit/reg_alloc_00[67].phpt ???
 					} else {
@@ -4206,7 +4204,6 @@ static const void *zend_jit_trace(zend_jit_trace_rec *trace_buffer, uint32_t par
 			 && (trace_buffer->stop == ZEND_JIT_TRACE_STOP_LOOP
 			  || trace_buffer->stop == ZEND_JIT_TRACE_STOP_RECURSIVE_CALL
 			  || (trace_buffer->stop == ZEND_JIT_TRACE_STOP_RECURSIVE_RET
-			   && (opline-1)->result_type == IS_VAR
 			   && EX_VAR_TO_NUM((opline-1)->result.var) == i))
 			 && (ssa->vars[i].use_chain != -1
 			  || (ssa->vars[i].phi_use_chain