I am re-testing the following patch to fix PR81065 with the
fold_addr_of_array_ref_difference hunk added which was the only
case causing the gcc_unreachable to trigger in a all languages
bootstrap and regtest on x86_64-unknown-linux-gnu. The patch
to commit will omit this case completely.
Bootstrap and regtest running on x86_64-unknown-linux-gnu.
Richard.
2017-06-12 Richard Biener <rguent...@suse.de>
PR middle-end/81065
* fold-const.c (extract_muldiv_1): Remove bogus distribution
case of C * (x * C2 + C3).
(fold_addr_of_array_ref_difference): Properly fold index difference.
* c-c++-common/ubsan/pr81065.c: New testcase.
Index: gcc/testsuite/c-c++-common/ubsan/pr81065.c
===================================================================
--- gcc/testsuite/c-c++-common/ubsan/pr81065.c (nonexistent)
+++ gcc/testsuite/c-c++-common/ubsan/pr81065.c (working copy)
@@ -0,0 +1,13 @@
+/* { dg-do run } */
+/* { dg-options "-fsanitize=undefined -fsanitize-undefined-trap-on-error" } */
+
+unsigned char x = 154;
+int foo() {
+ // 8575 * (254408 - 9057) = 8575 * 245351 = 2103884825 = 0x7d66bc19
+ return 8575 * (1652 * x - 9057);
+}
+
+int main() {
+ foo();
+ return 0;
+}
Index: gcc/fold-const.c
===================================================================
--- gcc/fold-const.c (revision 249112)
+++ gcc/fold-const.c (working copy)
@@ -6243,8 +6243,11 @@ extract_muldiv_1 (tree t, tree c, enum t
/* If we were able to eliminate our operation from the first side,
apply our operation to the second side and reform the PLUS. */
- if (t1 != 0 && (TREE_CODE (t1) != code || code == MULT_EXPR))
+ if (t1 != 0 && TREE_CODE (t1) != code)
+ {
+ gcc_unreachable ();
return fold_build2 (tcode, ctype, fold_convert (ctype, t1), op1);
+ }
/* The last case is if we are a multiply. In that case, we can
apply the distributive law to commute the multiply and addition
@@ -8908,7 +8911,7 @@ fold_addr_of_array_ref_difference (locat
tree op0 = fold_convert_loc (loc, type, TREE_OPERAND (aref0, 1));
tree op1 = fold_convert_loc (loc, type, TREE_OPERAND (aref1, 1));
tree esz = fold_convert_loc (loc, type, array_ref_element_size (aref0));
- tree diff = build2 (MINUS_EXPR, type, op0, op1);
+ tree diff = fold_build2_loc (loc, MINUS_EXPR, type, op0, op1);
return fold_build2_loc (loc, PLUS_EXPR, type,
base_offset,
fold_build2_loc (loc, MULT_EXPR, type,
