https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81719
Richard Biener <rguenth at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|UNCONFIRMED |ASSIGNED Last reconfirmed| |2017-08-08 Component|c++ |middle-end Ever confirmed|0 |1 --- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> --- We are not able to analyze the number of iterations and end up vectorizing the function. t.C:12:19: note: Symbolic number of iterations is (((unsigned long) __for_end_6 - (unsigned long) ((const int *) __for_range_5 + 4)) /[ex] 4 & 4611686018427387903) + 1 <bb 2> [15.00%]: __for_range_5 = &this_4(D)->items; __for_end_6 = &MEM[(void *)this_4(D) + 8B]; <bb 3> [85.00%]: # total_11 = PHI <total_9(4), 0(2)> # __for_begin_14 = PHI <__for_begin_10(4), __for_range_5(2)> item_8 = *__for_begin_14; total_9 = item_8 + total_11; __for_begin_10 = __for_begin_14 + 4; if (__for_end_6 == __for_begin_10) goto <bb 5>; [15.00%] else goto <bb 4>; [85.00%] <bb 4> [72.25%]: goto <bb 3>; [100.00%] <bb 5> [15.00%]: # total_12 = PHI <total_9(3)> it looks like expand_simple_operations fails to handle ADDR_EXPR in e = gimple_assign_rhs1 (stmt); code = gimple_assign_rhs_code (stmt); if (get_gimple_rhs_class (code) == GIMPLE_SINGLE_RHS) { if (is_gimple_min_invariant (e)) return e; if (code == SSA_NAME) return expand_simple_operations (e, stop); return expr; } but when it is sth that just mimics a POINTER_PLUS_EXPR it should. Index: gcc/tree-ssa-loop-niter.c =================================================================== --- gcc/tree-ssa-loop-niter.c (revision 250813) +++ gcc/tree-ssa-loop-niter.c (working copy) @@ -42,6 +42,7 @@ along with GCC; see the file COPYING3. #include "tree-chrec.h" #include "tree-scalar-evolution.h" #include "params.h" +#include "tree-dfa.h" /* The maximum number of dominator BBs we search for conditions @@ -1980,6 +1981,21 @@ expand_simple_operations (tree expr, tre if (code == SSA_NAME) return expand_simple_operations (e, stop); + else if (code == ADDR_EXPR) + { + HOST_WIDE_INT offset; + tree base = get_addr_base_and_unit_offset (TREE_OPERAND (e, 0), + &offset); + if (base + && TREE_CODE (base) == MEM_REF) + { + ee = expand_simple_operations (TREE_OPERAND (base, 0), stop); + return fold_build2 (POINTER_PLUS_EXPR, TREE_TYPE (expr), ee, + wide_int_to_tree (sizetype, + mem_ref_offset (base) + + offset)); + } + } return expr; }