[PATCH, committed] PR80158 cleanup (alternate interpretations)

[Bill Schmidt]

Hi,

The fix for PR80158 is technically correct, but not "future-proof" in the
sense that someday we may implement more than one alternate interpretation
for a strength reduction candidate.  This patch cleans that up.

Bootstrapped on powerpc64le-unknown-linux-gnu with no regressions,
committed.

Thanks,
Bill


2017-03-29  Bill Schmidt  <wschm...@linux.vnet.ibm.com>

        PR tree-optimization/80158
        * gimple-ssa-strength-reduction.c (replace_mult_candidate):
        Handle possible future case of more than one alternate
        interpretation.
        (replace_rhs_if_not_dup): Likewise.
        (replace_one_candidate): Likewise.


Index: gcc/gimple-ssa-strength-reduction.c
===================================================================
--- gcc/gimple-ssa-strength-reduction.c (revision 246554)
+++ gcc/gimple-ssa-strength-reduction.c (working copy)
@@ -2086,11 +2086,15 @@ replace_mult_candidate (slsr_cand_t c, tree basis_
          tree lhs = gimple_assign_lhs (c->cand_stmt);
          gassign *copy_stmt = gimple_build_assign (lhs, basis_name);
          gimple_stmt_iterator gsi = gsi_for_stmt (c->cand_stmt);
+         slsr_cand_t cc = c;
          gimple_set_location (copy_stmt, gimple_location (c->cand_stmt));
          gsi_replace (&gsi, copy_stmt, false);
          c->cand_stmt = copy_stmt;
-         if (c->next_interp)
-           lookup_cand (c->next_interp)->cand_stmt = copy_stmt;
+         while (cc->next_interp)
+           {
+             cc = lookup_cand (cc->next_interp);
+             cc->cand_stmt = copy_stmt;
+           }
          if (dump_file && (dump_flags & TDF_DETAILS))
            stmt_to_print = copy_stmt;
        }
@@ -2116,12 +2120,16 @@ replace_mult_candidate (slsr_cand_t c, tree basis_
          else
            {
              gimple_stmt_iterator gsi = gsi_for_stmt (c->cand_stmt);
+             slsr_cand_t cc = c;
              gimple_assign_set_rhs_with_ops (&gsi, code,
                                              basis_name, bump_tree);
              update_stmt (gsi_stmt (gsi));
               c->cand_stmt = gsi_stmt (gsi);
-             if (c->next_interp)
-               lookup_cand (c->next_interp)->cand_stmt = gsi_stmt (gsi);
+             while (cc->next_interp)
+               {
+                 cc = lookup_cand (cc->next_interp);
+                 cc->cand_stmt = gsi_stmt (gsi);
+               }
              if (dump_file && (dump_flags & TDF_DETAILS))
                stmt_to_print = gsi_stmt (gsi);
            }
@@ -3406,11 +3414,15 @@ replace_rhs_if_not_dup (enum tree_code new_code, t
              || !operand_equal_p (new_rhs2, old_rhs1, 0))))
     {
       gimple_stmt_iterator gsi = gsi_for_stmt (c->cand_stmt);
+      slsr_cand_t cc = c;
       gimple_assign_set_rhs_with_ops (&gsi, new_code, new_rhs1, new_rhs2);
       update_stmt (gsi_stmt (gsi));
       c->cand_stmt = gsi_stmt (gsi);
-      if (c->next_interp)
-       lookup_cand (c->next_interp)->cand_stmt = gsi_stmt (gsi);
+      while (cc->next_interp)
+       {
+         cc = lookup_cand (cc->next_interp);
+         cc->cand_stmt = gsi_stmt (gsi);
+       }
 
       if (dump_file && (dump_flags & TDF_DETAILS))
        return gsi_stmt (gsi);
@@ -3514,11 +3526,15 @@ replace_one_candidate (slsr_cand_t c, unsigned i,
          || !operand_equal_p (rhs2, orig_rhs2, 0))
        {
          gimple_stmt_iterator gsi = gsi_for_stmt (c->cand_stmt);
+         slsr_cand_t cc = c;
          gimple_assign_set_rhs_with_ops (&gsi, MINUS_EXPR, basis_name, rhs2);
          update_stmt (gsi_stmt (gsi));
           c->cand_stmt = gsi_stmt (gsi);
-         if (c->next_interp)
-           lookup_cand (c->next_interp)->cand_stmt = gsi_stmt (gsi);
+         while (cc->next_interp)
+           {
+             cc = lookup_cand (cc->next_interp);
+             cc->cand_stmt = gsi_stmt (gsi);
+           }
 
          if (dump_file && (dump_flags & TDF_DETAILS))
            stmt_to_print = gsi_stmt (gsi);
@@ -3537,11 +3553,15 @@ replace_one_candidate (slsr_cand_t c, unsigned i,
        {
          gassign *copy_stmt = gimple_build_assign (lhs, basis_name);
          gimple_stmt_iterator gsi = gsi_for_stmt (c->cand_stmt);
+         slsr_cand_t cc = c;
          gimple_set_location (copy_stmt, gimple_location (c->cand_stmt));
          gsi_replace (&gsi, copy_stmt, false);
          c->cand_stmt = copy_stmt;
-         if (c->next_interp)
-           lookup_cand (c->next_interp)->cand_stmt = copy_stmt;
+         while (cc->next_interp)
+           {
+             cc = lookup_cand (cc->next_interp);
+             cc->cand_stmt = copy_stmt;
+           }
 
          if (dump_file && (dump_flags & TDF_DETAILS))
            stmt_to_print = copy_stmt;
@@ -3550,11 +3570,15 @@ replace_one_candidate (slsr_cand_t c, unsigned i,
        {
          gimple_stmt_iterator gsi = gsi_for_stmt (c->cand_stmt);
          gassign *cast_stmt = gimple_build_assign (lhs, NOP_EXPR, basis_name);
+         slsr_cand_t cc = c;
          gimple_set_location (cast_stmt, gimple_location (c->cand_stmt));
          gsi_replace (&gsi, cast_stmt, false);
          c->cand_stmt = cast_stmt;
-         if (c->next_interp)
-           lookup_cand (c->next_interp)->cand_stmt = cast_stmt;
+         while (cc->next_interp)
+           {
+             cc = lookup_cand (cc->next_interp);
+             cc->cand_stmt = cast_stmt;
+           }
 
          if (dump_file && (dump_flags & TDF_DETAILS))
            stmt_to_print = cast_stmt;