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.
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
