Avoid creating useless debug temporaries

insert_debug_temp_for_var_def has some strange code whereby it creates
debug temporaries for SINGLE_RHS (RHS for gimple_assign_single_p) but
not for other RHS in the same situation.

gcc/
	* tree-ssa.cc (insert_debug_temp_for_var_def): Do not create
	superfluous debug temporaries for single GIMPLE assignments.

diff --git a/gcc/tree-ssa.cc b/gcc/tree-ssa.cc
index a5cad2d344e6d7d79961288b9bd1856aead35b0e..4ca1f5f3104c6fb79e3e0ccde3b95046d64762ce 100644 (file)
--- a/gcc/tree-ssa.cc
+++ b/gcc/tree-ssa.cc
@@ -412,8 +412,7 @@ insert_debug_temp_for_var_def (gimple_stmt_iterator *gsi, tree var)
     {
       /* If there's a single use of VAR, and VAR is the entire debug
         expression (usecount would have been incremented again
-        otherwise), and the definition involves only constants and
-        SSA names, then we can propagate VALUE into this single use,
+        otherwise), then we can propagate VALUE into this single use,
         avoiding the temp.
 
         We can also avoid using a temp if VALUE can be shared and
@@ -424,11 +423,9 @@ insert_debug_temp_for_var_def (gimple_stmt_iterator *gsi, tree var)
         are deferred to a debug temp, although we could avoid temps
         at the expense of duplication of expressions.  */
 
-      if (CONSTANT_CLASS_P (value)
+      if (usecount == 1
          || gimple_code (def_stmt) == GIMPLE_PHI
-         || (usecount == 1
-             && (!gimple_assign_single_p (def_stmt)
-                 || is_gimple_min_invariant (value)))
+         || CONSTANT_CLASS_P (value)
          || is_gimple_reg (value))
        ;
       else
@@ -466,11 +463,6 @@ insert_debug_temp_for_var_def (gimple_stmt_iterator *gsi, tree var)
       if (value)
        {
          FOR_EACH_IMM_USE_ON_STMT (use_p, imm_iter)
-           /* unshare_expr is not needed here.  vexpr is either a
-              SINGLE_RHS, that can be safely shared, some other RHS
-              that was unshared when we found it had a single debug
-              use, or a DEBUG_EXPR_DECL, that can be safely
-              shared.  */
            SET_USE (use_p, unshare_expr (value));
          /* If we didn't replace uses with a debug decl fold the
             resulting expression.  Otherwise we end up with invalid IL.  */