The following improves niter analysis for range-based for loops
by handling ADDR_EXPR in expand_simple_operations.
Bootstrapped on x86_64-unknown-linux-gnu, testing in progress.
Richard.
2017-08-08 Richard Biener <rguent...@suse.de>
PR middle-end/81719
* tree-ssa-loop-niter.c: Include tree-dfa.h.
(expand_simple_operations): Also look through ADDR_EXPRs with
MEM_REF bases treating them as POINTER_PLUS_EXPR.
* g++.dg/tree-ssa/pr81719.C: New testcase.
Index: gcc/tree-ssa-loop-niter.c
===================================================================
*** gcc/tree-ssa-loop-niter.c (revision 250813)
--- gcc/tree-ssa-loop-niter.c (working copy)
*************** along with GCC; see the file COPYING3.
*** 42,47 ****
--- 42,48 ----
#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
*************** expand_simple_operations (tree expr, tre
*** 1980,1985 ****
--- 1981,2001 ----
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;
}
Index: gcc/testsuite/g++.dg/tree-ssa/pr81719.C
===================================================================
*** gcc/testsuite/g++.dg/tree-ssa/pr81719.C (nonexistent)
--- gcc/testsuite/g++.dg/tree-ssa/pr81719.C (working copy)
***************
*** 0 ****
--- 1,24 ----
+ /* { dg-do compile { target c++11 } } */
+ /* { dg-options "-O3 -fdump-tree-optimized" } */
+
+ typedef int Items[2];
+
+ struct ItemArray
+ {
+ Items items;
+ int sum_x2() const;
+ };
+
+ int ItemArray::sum_x2() const
+ {
+ int total = 0;
+ for (int item : items)
+ {
+ total += item;
+ }
+ return total;
+ }
+
+ /* We should be able to compute the number of iterations to two, unroll
+ the loop and end up with a single basic-block in sum_x2. */
+ /* { dg-final { scan-tree-dump-times "bb" 1 "optimized" } } */
