When testing PR 85164, the baseline bootstrap-ubsan results had
a lot of failures from int_const_binop. This is because with the
new overflow handling we can sometimes do:
poly_res = res;
on an uninitialised res.
Tested with bootstrap-ubsan on aarch64-linux-gnu and x86_64-linux-gnu.
OK to install? (This is a GCC 9 regression FWIW.)
Richard
2019-04-18 Richard Sandiford <[email protected]>
gcc/
* fold-const.c (int_const_binop): Return early on failure.
Index: gcc/fold-const.c
===================================================================
--- gcc/fold-const.c 2019-04-04 08:34:52.001938080 +0100
+++ gcc/fold-const.c 2019-04-18 10:11:12.336697917 +0100
@@ -1173,7 +1173,6 @@ poly_int_binop (poly_wide_int &res, enum
int_const_binop (enum tree_code code, const_tree arg1, const_tree arg2,
int overflowable)
{
- bool success = false;
poly_wide_int poly_res;
tree type = TREE_TYPE (arg1);
signop sign = TYPE_SIGN (type);
@@ -1183,17 +1182,18 @@ int_const_binop (enum tree_code code, co
{
wide_int warg1 = wi::to_wide (arg1), res;
wide_int warg2 = wi::to_wide (arg2, TYPE_PRECISION (type));
- success = wide_int_binop (res, code, warg1, warg2, sign, &overflow);
+ if (!wide_int_binop (res, code, warg1, warg2, sign, &overflow))
+ return NULL_TREE;
poly_res = res;
}
- else if (poly_int_tree_p (arg1) && poly_int_tree_p (arg2))
- success = poly_int_binop (poly_res, code, arg1, arg2, sign, &overflow);
- if (success)
- return force_fit_type (type, poly_res, overflowable,
- (((sign == SIGNED || overflowable == -1)
- && overflow)
- | TREE_OVERFLOW (arg1) | TREE_OVERFLOW (arg2)));
- return NULL_TREE;
+ else if (!poly_int_tree_p (arg1)
+ || !poly_int_tree_p (arg2)
+ || !poly_int_binop (poly_res, code, arg1, arg2, sign, &overflow))
+ return NULL_TREE;
+ return force_fit_type (type, poly_res, overflowable,
+ (((sign == SIGNED || overflowable == -1)
+ && overflow)
+ | TREE_OVERFLOW (arg1) | TREE_OVERFLOW (arg2)));
}
/* Return true if binary operation OP distributes over addition in operand
