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?
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
