[PATCH, rs6000] enable early debug and disable switch for gimple folding

[Will Schmidt]

Hi, 

[PATCH, rs6000] enable early debug and disable switch for gimple folding
    
Enable debug options related to gimple folding for the rs6000 target.
Adds some output to the existing -mdebug=builtin option
Add a -mgimple-folding=off option to disable the early rs6000 gimple folding.

OK for trunk?

Thanks,
-Will


[gcc]
    
        2017-08-08  Will Schmidt  <will_schm...@vnet.ibm.com>
    
        * config/rs6000/rs6000.c: rs6000_option_override_internal() Add blurb
        to indicate when early gimple folding has been disabled.
        rs6000_gimple_fold_builtin(): Add debug content.

diff --git a/gcc/config/rs6000/rs6000.c b/gcc/config/rs6000/rs6000.c
index 1fb9861..0466fd0 100644
--- a/gcc/config/rs6000/rs6000.c
+++ b/gcc/config/rs6000/rs6000.c
@@ -4180,10 +4180,14 @@ rs6000_option_override_internal (bool global_init_p)
     {
       warning (0, N_("-maltivec=le not allowed for big-endian targets"));
       rs6000_altivec_element_order = 0;
     }
 
+  if (rs6000_gimple_folding_disable)
+     fprintf (stderr,
+     "gimple folding of rs6000 builtins has been disabled.\n");
+
   /* Add some warnings for VSX.  */
   if (TARGET_VSX)
     {
       const char *msg = NULL;
       if (!TARGET_HARD_FLOAT || !TARGET_SINGLE_FLOAT || !TARGET_DOUBLE_FLOAT)
@@ -16157,10 +16161,26 @@ rs6000_gimple_fold_builtin (gimple_stmt_iterator *gsi)
   gcc_checking_assert (fndecl && DECL_BUILT_IN_CLASS (fndecl) == BUILT_IN_MD);
   enum rs6000_builtins fn_code
     = (enum rs6000_builtins) DECL_FUNCTION_CODE (fndecl);
   tree arg0, arg1, lhs;
 
+  size_t uns_fncode = (size_t)fn_code;
+  enum insn_code icode = rs6000_builtin_info[uns_fncode].icode;
+  const char *fn_name1 = rs6000_builtin_info[uns_fncode].name;
+  const char *fn_name2 = ((icode != CODE_FOR_nothing)
+                         ? get_insn_name ((int)icode)
+                         : "nothing");
+
+  if (TARGET_DEBUG_BUILTIN)
+  {
+      fprintf (stderr, "rs6000_gimple_fold_builtin %d %s %s \n",
+              fn_code,fn_name1,fn_name2);
+  }
+
+  if (rs6000_gimple_folding_disable)
+     return false;
+
   /* Generic solution to prevent gimple folding of code without a LHS.  */
   if (!gimple_call_lhs (stmt))
     return false;
 
   switch (fn_code)
@@ -16516,10 +16536,13 @@ rs6000_gimple_fold_builtin (gimple_stmt_iterator *gsi)
        gsi_insert_seq_before (gsi, stmts, GSI_SAME_STMT);
        update_call_from_tree (gsi, res);
        return true;
       }
     default:
+       if (TARGET_DEBUG_BUILTIN)
+          fprintf (stderr, "gimple builtin intrinsic not matched:%d %s %s \n",
+                          fn_code,fn_name1,fn_name2);
       break;
     }
 
   return false;
 }
diff --git a/gcc/config/rs6000/rs6000.opt b/gcc/config/rs6000/rs6000.opt
index e94aa07..4372b00 100644
--- a/gcc/config/rs6000/rs6000.opt
+++ b/gcc/config/rs6000/rs6000.opt
@@ -146,10 +146,14 @@ Generate AltiVec instructions using little-endian element 
order.
 
 maltivec=be
 Target Report RejectNegative Var(rs6000_altivec_element_order, 2)
 Generate AltiVec instructions using big-endian element order.
 
+mgimple-folding=off
+Target Report RejectNegative Var(rs6000_gimple_folding_disable, 1)
+Disable early gimple folding of builtins.
+
 mhard-dfp
 Target Report Mask(DFP) Var(rs6000_isa_flags)
 Use decimal floating point instructions.
 
 mmulhw