diff --git a/ext/opcache/Optimizer/sccp.c b/ext/opcache/Optimizer/sccp.c
index fe3ff0f921a..01e3157506d 100644
--- a/ext/opcache/Optimizer/sccp.c
+++ b/ext/opcache/Optimizer/sccp.c
@@ -1192,13 +1192,14 @@ static void sccp_visit_phi(scdf_ctx *scdf, zend_ssa_phi *phi) {
 		MAKE_TOP(&result);
 		SCP_DEBUG("Handling PHI(");
 		if (phi->pi >= 0) {
-			if (phi->sources[0] >= 0 && scdf_is_edge_feasible(scdf, phi->pi, phi->block)) {
+			ZEND_ASSERT(phi->sources[0] >= 0);
+			if (scdf_is_edge_feasible(scdf, phi->pi, phi->block)) {
 				join_phi_values(&result, &ctx->values[phi->sources[0]]);
 			}
 		} else {
 			for (i = 0; i < block->predecessors_count; i++) {
-				if (phi->sources[i] >= 0
-						&& scdf_is_edge_feasible(scdf, predecessors[i], phi->block)) {
+				ZEND_ASSERT(phi->sources[i] >= 0);
+				if (scdf_is_edge_feasible(scdf, predecessors[i], phi->block)) {
 					SCP_DEBUG("val, ");
 					join_phi_values(&result, &ctx->values[phi->sources[i]]);
 				} else {
diff --git a/ext/opcache/Optimizer/zend_inference.c b/ext/opcache/Optimizer/zend_inference.c
index 5234bc8ef6e..a3d1be177e0 100644
--- a/ext/opcache/Optimizer/zend_inference.c
+++ b/ext/opcache/Optimizer/zend_inference.c
@@ -282,7 +282,8 @@ int zend_ssa_find_false_dependencies(const zend_op_array *op_array, zend_ssa *ss
 				}
 			} else {
 				for (j = 0; j < ssa->cfg.blocks[p->block].predecessors_count; j++) {
-					if (p->sources[j] >= 0 && ssa->vars[p->sources[j]].no_val) {
+					ZEND_ASSERT(p->sources[j] >= 0);
+					if (ssa->vars[p->sources[j]].no_val) {
 						ssa_vars[p->sources[j]].no_val = 0; /* used indirectly */
 						zend_bitset_incl(worklist, p->sources[j]);
 					}
@@ -854,7 +855,8 @@ int zend_inference_calc_range(const zend_op_array *op_array, zend_ssa *ssa, int
 			}
 		} else {
 			for (i = 0; i < ssa->cfg.blocks[p->block].predecessors_count; i++) {
-				if (p->sources[i] >= 0 && ssa->var_info[p->sources[i]].has_range) {
+				ZEND_ASSERT(p->sources[i] >= 0);
+				if (ssa->var_info[p->sources[i]].has_range) {
 					/* union */
 					tmp->underflow |= ssa->var_info[p->sources[i]].range.underflow;
 					tmp->min = MIN(tmp->min, ssa->var_info[p->sources[i]].range.min);
@@ -3328,17 +3330,18 @@ int zend_infer_types_ex(const zend_op_array *op_array, const zend_script *script
 				}
 				UPDATE_SSA_TYPE(tmp, j);
 				for (i = 0; i < blocks[p->block].predecessors_count; i++) {
-					if (p->sources[i] >= 0) {
-						zend_ssa_var_info *info = &ssa_var_info[p->sources[i]];
-						if (info->type & MAY_BE_OBJECT) {
-							if (first) {
-								ce = info->ce;
-								is_instanceof = info->is_instanceof;
-								first = 0;
-							} else {
-								is_instanceof |= info->is_instanceof;
-								ce = join_class_entries(ce, info->ce, &is_instanceof);
-							}
+					zend_ssa_var_info *info;
+
+					ZEND_ASSERT(p->sources[i] >= 0);
+					info = &ssa_var_info[p->sources[i]];
+					if (info->type & MAY_BE_OBJECT) {
+						if (first) {
+							ce = info->ce;
+							is_instanceof = info->is_instanceof;
+							first = 0;
+						} else {
+							is_instanceof |= info->is_instanceof;
+							ce = join_class_entries(ce, info->ce, &is_instanceof);
 						}
 					}
 				}
diff --git a/ext/opcache/Optimizer/zend_ssa.c b/ext/opcache/Optimizer/zend_ssa.c
index 0df62ddb1db..3547e2bc9d2 100644
--- a/ext/opcache/Optimizer/zend_ssa.c
+++ b/ext/opcache/Optimizer/zend_ssa.c
@@ -1061,15 +1061,16 @@ int zend_ssa_compute_use_def_chains(zend_arena **arena, const zend_op_array *op_
 			ssa_vars[phi->ssa_var].var = phi->var;
 			ssa_vars[phi->ssa_var].definition_phi = phi;
 			if (phi->pi >= 0) {
-				if (phi->sources[0] >= 0) {
-					zend_ssa_phi *p = ssa_vars[phi->sources[0]].phi_use_chain;
-					while (p && p != phi) {
-						p = zend_ssa_next_use_phi(ssa, phi->sources[0], p);
-					}
-					if (!p) {
-						phi->use_chains[0] = ssa_vars[phi->sources[0]].phi_use_chain;
-						ssa_vars[phi->sources[0]].phi_use_chain = phi;
-					}
+				zend_ssa_phi *p;
+
+				ZEND_ASSERT(phi->sources[0] >= 0);
+				p = ssa_vars[phi->sources[0]].phi_use_chain;
+				while (p && p != phi) {
+					p = zend_ssa_next_use_phi(ssa, phi->sources[0], p);
+				}
+				if (!p) {
+					phi->use_chains[0] = ssa_vars[phi->sources[0]].phi_use_chain;
+					ssa_vars[phi->sources[0]].phi_use_chain = phi;
 				}
 				if (phi->has_range_constraint) {
 					/* min and max variables can't be used together */
@@ -1086,15 +1087,16 @@ int zend_ssa_compute_use_def_chains(zend_arena **arena, const zend_op_array *op_
 				int j;
 
 				for (j = 0; j < ssa->cfg.blocks[i].predecessors_count; j++) {
-					if (phi->sources[j] >= 0) {
-						zend_ssa_phi *p = ssa_vars[phi->sources[j]].phi_use_chain;
-						while (p && p != phi) {
-							p = zend_ssa_next_use_phi(ssa, phi->sources[j], p);
-						}
-						if (!p) {
-							phi->use_chains[j] = ssa_vars[phi->sources[j]].phi_use_chain;
-							ssa_vars[phi->sources[j]].phi_use_chain = phi;
-						}
+					zend_ssa_phi *p;
+
+					ZEND_ASSERT(phi->sources[j] >= 0);
+					p = ssa_vars[phi->sources[j]].phi_use_chain;
+					while (p && p != phi) {
+						p = zend_ssa_next_use_phi(ssa, phi->sources[j], p);
+					}
+					if (!p) {
+						phi->use_chains[j] = ssa_vars[phi->sources[j]].phi_use_chain;
+						ssa_vars[phi->sources[j]].phi_use_chain = phi;
 					}
 				}
 			}
@@ -1315,9 +1317,6 @@ void zend_ssa_remove_uses_of_var(zend_ssa *ssa, int var_num) /* {{{ */
 		int i, end = NUM_PHI_SOURCES(phi);
 		for (i = 0; i < end; i++) {
 			if (phi->sources[i] == var_num) {
-#if 0
-				phi->sources[i] = -1;
-#endif
 				phi->use_chains[i] = NULL;
 			}
 		}
@@ -1395,9 +1394,8 @@ void zend_ssa_remove_block(zend_op_array *op_array, zend_ssa *ssa, int i) /* {{{
 					zend_ssa_remove_phi(ssa, phi);
 				}
 			} else {
-				if (phi->sources[pred_offset] >= 0) {
-					zend_ssa_remove_phi_source(ssa, phi, pred_offset, next_block->predecessors_count);
-				}
+				ZEND_ASSERT(phi->sources[pred_offset] >= 0);
+				zend_ssa_remove_phi_source(ssa, phi, pred_offset, next_block->predecessors_count);
 			}
 		}
 
diff --git a/ext/opcache/Optimizer/zend_ssa.h b/ext/opcache/Optimizer/zend_ssa.h
index 943f47c5d5a..1cfe58a1078 100644
--- a/ext/opcache/Optimizer/zend_ssa.h
+++ b/ext/opcache/Optimizer/zend_ssa.h
@@ -240,7 +240,7 @@ static zend_always_inline zend_bool zend_ssa_is_no_val_use(const zend_op *opline
 	zend_ssa_phi *_phi = (phi); \
 	int _i, _end = NUM_PHI_SOURCES(phi); \
 	for (_i = 0; _i < _end; _i++) { \
-		if (_phi->sources[_i] < 0) continue; \
+		ZEND_ASSERT(_phi->sources[_i] >= 0); \
 		source = _phi->sources[_i];
 #define FOREACH_PHI_SOURCE_END() \
 	} \