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Re: [PATCH, Pointer Bounds Checker 14/x] Passes [8/n] Remove useless builtin calls


On 10/08/14 13:08, Ilya Enkovich wrote:
Hi,

This patch adds removal of user calls to chkp builtins which become useless after instrumentation.

Thanks,
Ilya
--
2014-10-08  Ilya Enkovich  <ilya.enkovich@intel.com>

	* tree-chkp.c (chkp_remove_useless_builtins): New.
	(chkp_execute): Remove useless calls to Pointer Bounds
	Checker builtins.
Please put this in the file with the optimizations. Tests too, which may require you to add some dumping bits into this code since you may not be able to directly see the behaviour you want in the gimple dumps later.

What I'm a bit confused about is it looks like every one of these builtin calls you end up optimizing -- why not generate the simple copy in the first place and avoid the need for chkp_remove_useless_builtins completely? Clearly I'm missing something here.




diff --git a/gcc/tree-chkp.c b/gcc/tree-chkp.c
index 5443950..b424af8 100644
--- a/gcc/tree-chkp.c
+++ b/gcc/tree-chkp.c
@@ -3805,6 +3805,49 @@ chkp_instrument_function (void)
  	}
  }

+/* Find init/null/copy_ptr_bounds calls and replace them
+   with assignments.  It should allow better code
+   optimization.  */
+
+static void
+chkp_remove_useless_builtins ()
+{
+  basic_block bb, next;
+  gimple_stmt_iterator gsi;
+
+  bb = ENTRY_BLOCK_PTR_FOR_FN (cfun)->next_bb;
+  do
+    {
+      next = bb->next_bb;
+      for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
+        {
+          gimple stmt = gsi_stmt (gsi);
+	  tree fndecl;
+	  enum built_in_function fcode;
There's some kind of formatting goof on one or more of the preceeding lines. They should be at the same indention level. Most likely they aren't consistent with their use of tabs vs spaces. A nit, but please take care of it.

If we end up keeping this code, then I think it'll be fine with the whitespace nit fixed. I just want to make sure there's a good reason to generate these builtins in the first place rather than the more direct assignment.

THanks,
Jeff


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