Re: [PATCH] Fix PR middle-end/37669

[Adam Nemet <anemet at caviumnetworks dot com>]

Jakub Jelinek writes:
> See my comment in bugzilla, I think this is an overkill, we should just
> remove the loop which might have been useful when we had to iterate through
> the arguments, but isn't any longer.  The only values of arg_mask are
> 1, 2 and 4 and val array has 3 elements anyway, so if you want to keep the
> loop, you could at least use i < nargs && i < 3, which is cheaper than
> floor_log2.

Here is an untested version of the patch without the loop.  I can give it a
round of testing if you like this better.

Adam

Index: tree-ssa-ccp.c
===================================================================
--- tree-ssa-ccp.c	(revision 141180)
+++ tree-ssa-ccp.c	(working copy)
@@ -2430,7 +2430,7 @@ ccp_fold_builtin (gimple stmt)
 {
   tree result, val[3];
   tree callee, a;
-  int arg_mask, i, type;
+  int len_arg, type;
   bitmap visited;
   bool ignore;
   int nargs;
@@ -2466,12 +2466,12 @@ ccp_fold_builtin (gimple stmt)
     case BUILT_IN_STRLEN:
     case BUILT_IN_FPUTS:
     case BUILT_IN_FPUTS_UNLOCKED:
-      arg_mask = 1;
+      len_arg = 0;
       type = 0;
       break;
     case BUILT_IN_STRCPY:
     case BUILT_IN_STRNCPY:
-      arg_mask = 2;
+      len_arg = 1;
       type = 0;
       break;
     case BUILT_IN_MEMCPY_CHK:
@@ -2479,17 +2479,17 @@ ccp_fold_builtin (gimple stmt)
     case BUILT_IN_MEMMOVE_CHK:
     case BUILT_IN_MEMSET_CHK:
     case BUILT_IN_STRNCPY_CHK:
-      arg_mask = 4;
+      len_arg = 2;
       type = 2;
       break;
     case BUILT_IN_STRCPY_CHK:
     case BUILT_IN_STPCPY_CHK:
-      arg_mask = 2;
+      len_arg = 1;
       type = 1;
       break;
     case BUILT_IN_SNPRINTF_CHK:
     case BUILT_IN_VSNPRINTF_CHK:
-      arg_mask = 2;
+      len_arg = 1;
       type = 2;
       break;
     default:
@@ -2498,18 +2498,12 @@ ccp_fold_builtin (gimple stmt)
 
   /* Try to use the dataflow information gathered by the CCP process.  */
   visited = BITMAP_ALLOC (NULL);
+  bitmap_clear (visited);
 
   memset (val, 0, sizeof (val));
-  for (i = 0; i < nargs; i++)
-    {
-      if ((arg_mask >> i) & 1)
-        {
-          a = gimple_call_arg (stmt, i);
-          bitmap_clear (visited);
-          if (!get_maxval_strlen (a, &val[i], visited, type))
-            val[i] = NULL_TREE;
-        }
-    }
+  a = gimple_call_arg (stmt, len_arg);
+  if (!get_maxval_strlen (a, &val[len_arg], visited, type))
+    val[len_arg] = NULL_TREE;
 
   BITMAP_FREE (visited);