re PR tree-optimization/77937 (ICE: in replace_one_candidate, at gimple-ssa-strength...

2016-10-13  Bill Schmidt  <wschmidt@linux.vnet.ibm.com>

	PR tree-optimization/77937
	* gimple-ssa-strength-reduction.c (analyze_increments): Set cost
	to infinite when we have a pointer with an increment of -1.

From-SVN: r241125

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index dfd16fe..7362986 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2016-10-13  Bill Schmidt  <wschmidt@linux.vnet.ibm.com>
+
+       PR tree-optimization/77937
+       * gimple-ssa-strength-reduction.c (analyze_increments): Set cost
+       to infinite when we have a pointer with an increment of -1.
+
 2016-10-13  Thomas Preud'homme  <thomas.preudhomme@arm.com>
 
        * coretypes.h: Move MEMMODEL_* macros and enum memmodel definition

diff --git a/gcc/gimple-ssa-strength-reduction.c b/gcc/gimple-ssa-strength-reduction.c
index cfa50d3..72862f8 100644 (file)
--- a/gcc/gimple-ssa-strength-reduction.c
+++ b/gcc/gimple-ssa-strength-reduction.c
@@ -2818,6 +2818,11 @@ analyze_increments (slsr_cand_t first_dep, machine_mode mode, bool speed)
               || (incr == -1
                   && !POINTER_TYPE_P (first_dep->cand_type)))
        incr_vec[i].cost = COST_NEUTRAL;
+
+      /* FIXME: We don't handle pointers with a -1 increment yet.
+         They are usually unprofitable anyway.  */
+      else if (incr == -1 && POINTER_TYPE_P (first_dep->cand_type))
+       incr_vec[i].cost = COST_INFINITE;
       
       /* FORNOW: If we need to add an initializer, give up if a cast from
         the candidate's type to its stride's type can lose precision.