https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114108
--- Comment #8 from Tejas Belagod <belagod at gcc dot gnu.org> --- I find this transformation a bit odd: ... pr114108.c:11:21: note: add new stmt: vect_patt_32.15_181 = .ABD (vect__3.11_177, vect__7.14_180); pr114108.c:11:21: note: ------>vectorizing statement: patt_31 = (unsigned char) patt_32; pr114108.c:11:21: note: transform statement. pr114108.c:11:21: note: vect_is_simple_use: operand .ABD (_3, _7), type of def: internal pr114108.c:11:21: note: vect_is_simple_use: vectype vector([16,16]) unsigned char pr114108.c:11:21: note: transform assignment. pr114108.c:11:21: note: vect_get_vec_defs_for_operand: patt_32 pr114108.c:11:21: note: vect_is_simple_use: operand .ABD (_3, _7), type of def: internal pr114108.c:11:21: note: def_stmt = patt_32 = .ABD (_3, _7); pr114108.c:11:21: note: add new stmt: vect_patt_31.16_182 = VIEW_CONVERT_EXPR<vector([16,16]) signed char>(vect_patt_32.15_181); ... This seems to have a cascading effect on the MIN_EXPR vectorization: pr114108.c:11:21: note: ------>vectorizing statement: patt_30 = (int) patt_31; pr114108.c:11:21: note: ------>vectorizing statement: _11 = dst_18(D) + _1; pr114108.c:11:21: note: ------>vectorizing statement: patt_29 = MIN_EXPR <patt_31, 127>; pr114108.c:11:21: note: transform statement. pr114108.c:11:21: note: vect_is_simple_use: operand (unsigned char) patt_32, type of def: internal pr114108.c:11:21: note: vect_is_simple_use: vectype vector([16,16]) signed char pr114108.c:11:21: note: vect_is_simple_use: operand 127, type of def: constant pr114108.c:11:21: note: transform binary/unary operation. pr114108.c:11:21: note: vect_get_vec_defs_for_operand: patt_31 pr114108.c:11:21: note: vect_is_simple_use: operand (unsigned char) patt_32, type of def: internal pr114108.c:11:21: note: def_stmt = patt_31 = (unsigned char) patt_32; pr114108.c:11:21: note: vect_get_vec_defs_for_operand: 127 pr114108.c:11:21: note: vect_is_simple_use: operand 127, type of def: constant pr114108.c:11:21: note: created new init_stmt: vect_cst__183 = { 127, ... }; pr114108.c:11:21: note: add new stmt: vect_patt_29.17_184 = MIN_EXPR <vect_patt_31.16_182, vect_cst__183>; I suspect that when narrowing analysis drops patt_30 = (int) patt_31; and replaces patt_30 in MIN_EXPR directly with patt_31, the pre-computed vector type_out for patt_30 = (int) patt_31; might be getting reused without getting recomputed. Still digging to see if this theory holds water...