Hi!
The C fully folding code expects that EXCESS_PRECISION_EXPR is never
the rhs of a COMPOUND_EXPR, instead it should wrap the whole COMPOUND_EXPR
if needed. The following patch does that, bootstrapped/regtested on
x86_64-linux and i686-linux, ok for trunk?
2017-03-20 Jakub Jelinek <ja...@redhat.com>
PR c/80097
* c-typeck.c (build_binary_op): Add EXCESS_PRECISION_EXPR only around
optional COMPOUND_EXPR with ubsan instrumentation.
* gcc.dg/ubsan/pr80097.c: New test.
--- gcc/c/c-typeck.c.jj 2017-03-16 17:18:24.000000000 +0100
+++ gcc/c/c-typeck.c 2017-03-20 08:59:37.515399725 +0100
@@ -11856,14 +11856,16 @@ build_binary_op (location_t location, en
else if (TREE_CODE (ret) != INTEGER_CST && int_operands
&& !in_late_binary_op)
ret = note_integer_operands (ret);
- if (semantic_result_type)
- ret = build1 (EXCESS_PRECISION_EXPR, semantic_result_type, ret);
protected_set_expr_location (ret, location);
if (instrument_expr != NULL)
ret = fold_build2 (COMPOUND_EXPR, TREE_TYPE (ret),
instrument_expr, ret);
+ if (semantic_result_type)
+ ret = build1_loc (location, EXCESS_PRECISION_EXPR,
+ semantic_result_type, ret);
+
return ret;
}
--- gcc/testsuite/gcc.dg/ubsan/pr80097.c.jj 2017-03-20 08:58:24.227483256
+0100
+++ gcc/testsuite/gcc.dg/ubsan/pr80097.c 2017-03-20 08:57:15.000000000
+0100
@@ -0,0 +1,10 @@
+/* PR c/80097 */
+/* { dg-do compile } */
+/* { dg-options "-std=c89 -fsanitize=float-divide-by-zero" } */
+
+int
+foo (double a)
+{
+ int b = (1 / a >= 1);
+ return b;
+}
Jakub
