On September 1, 2017 3:53:28 PM GMT+02:00, Jakub Jelinek <ja...@redhat.com>
wrote:
>On Fri, Sep 01, 2017 at 02:32:43PM +0200, Richard Biener wrote:
>> On September 1, 2017 1:16:54 PM GMT+02:00, Jakub Jelinek
><ja...@redhat.com> wrote:
>> >Hi!
>> >
>> >This patch fixes the following testcase by folding some ubsan
>internal
>> >fns
>> >we'd either remove anyway during sanopt, or lower into if (cond)
>> >do_something during sanopt where cond would be always false.
>> >
>> >Additionally, I've tried to clean up a little bit
>IFN_UBSAN_OBJECT_SIZE
>> >handling by using variables for the call arguments that make it
>clear
>> >what the arguments are.
>> >
>> >Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
>>
>> I think there's a helper for replace - with-nop.
>
>Can't find it.
>gimplify_and_update_call_from_tree has to add it, but I'd need
>to call it with something that gimplifies into empty sequence
>(void_node?)
>and it would still go through
>push_gimplify_context/gimplify_and_add/pop_gimplify_context
>etc., which looks quite expensive.
OK, I thought we have one. Can you add a helper for it please? replace_with_nop
or so? I thought there's maybe replace_with_value which handles null lhs by
replacing with nop. (can't check, writing from phone)
Richard.
>> >2017-09-01 Jakub Jelinek <ja...@redhat.com>
>> >
>> > PR sanitizer/81981
>> > * gimple-fold.c (gimple_fold_call): Optimize away useless UBSAN_PTR
>> > and UBSAN_BOUNDS internal calls. Clean up IFN_UBSAN_OBJECT_SIZE
>> > handling.
>> >
>> > * gcc.dg/ubsan/pr81981.c: New test.
>> >
>> >--- gcc/gimple-fold.c.jj 2017-08-10 02:31:21.000000000 +0200
>> >+++ gcc/gimple-fold.c 2017-08-29 18:50:49.993673432 +0200
>> >@@ -3938,11 +3938,23 @@ gimple_fold_call (gimple_stmt_iterator *
>> > gimple_call_arg (stmt, 2));
>> > break;
>> > case IFN_UBSAN_OBJECT_SIZE:
>> >- if (integer_all_onesp (gimple_call_arg (stmt, 2))
>> >- || (TREE_CODE (gimple_call_arg (stmt, 1)) == INTEGER_CST
>> >- && TREE_CODE (gimple_call_arg (stmt, 2)) == INTEGER_CST
>> >- && tree_int_cst_le (gimple_call_arg (stmt, 1),
>> >- gimple_call_arg (stmt, 2))))
>> >+ {
>> >+ tree offset = gimple_call_arg (stmt, 1);
>> >+ tree objsize = gimple_call_arg (stmt, 2);
>> >+ if (integer_all_onesp (objsize)
>> >+ || (TREE_CODE (offset) == INTEGER_CST
>> >+ && TREE_CODE (objsize) == INTEGER_CST
>> >+ && tree_int_cst_le (offset, objsize)))
>> >+ {
>> >+ gsi_replace (gsi, gimple_build_nop (), false);
>> >+ unlink_stmt_vdef (stmt);
>> >+ release_defs (stmt);
>> >+ return true;
>> >+ }
>> >+ }
>> >+ break;
>> >+ case IFN_UBSAN_PTR:
>> >+ if (integer_zerop (gimple_call_arg (stmt, 1)))
>> > {
>> > gsi_replace (gsi, gimple_build_nop (), false);
>> > unlink_stmt_vdef (stmt);
>> >@@ -3950,6 +3962,25 @@ gimple_fold_call (gimple_stmt_iterator *
>> > return true;
>> > }
>> > break;
>> >+ case IFN_UBSAN_BOUNDS:
>> >+ {
>> >+ tree index = gimple_call_arg (stmt, 1);
>> >+ tree bound = gimple_call_arg (stmt, 2);
>> >+ if (TREE_CODE (index) == INTEGER_CST
>> >+ && TREE_CODE (bound) == INTEGER_CST)
>> >+ {
>> >+ index = fold_convert (TREE_TYPE (bound), index);
>> >+ if (TREE_CODE (index) == INTEGER_CST
>> >+ && tree_int_cst_le (index, bound))
>> >+ {
>> >+ gsi_replace (gsi, gimple_build_nop (), false);
>> >+ unlink_stmt_vdef (stmt);
>> >+ release_defs (stmt);
>> >+ return true;
>> >+ }
>> >+ }
>> >+ }
>> >+ break;
>> > case IFN_GOACC_DIM_SIZE:
>> > case IFN_GOACC_DIM_POS:
>> > result = fold_internal_goacc_dim (stmt);
>> >--- gcc/testsuite/gcc.dg/ubsan/pr81981.c.jj 2017-08-29
>> >18:54:33.826107761 +0200
>> >+++ gcc/testsuite/gcc.dg/ubsan/pr81981.c 2017-08-29
>18:55:36.721386827
>> >+0200
>> >@@ -0,0 +1,21 @@
>> >+/* PR sanitizer/81981 */
>> >+/* { dg-do compile } */
>> >+/* { dg-options "-O2 -Wmaybe-uninitialized -fsanitize=undefined
>> >-ffat-lto-objects" } */
>> >+
>> >+int v;
>> >+
>> >+int
>> >+foo (int i)
>> >+{
>> >+ int t[1], u[1];
>> >+ int n = 0;
>> >+
>> >+ if (i)
>> >+ {
>> >+ t[n] = i;
>> >+ u[0] = i;
>> >+ }
>> >+
>> >+ v = u[0]; /* { dg-warning "may be used uninitialized in
>> >this
>> >function" } */
>> >+ return t[0]; /* { dg-warning "may be used uninitialized in
>> >this
>> >function" } */
>> >+}
>> >
>> > Jakub
>
> Jakub
