http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46679
Summary: fold_binary changes types in divisionm breaking
configure -enable-checking
Product: gcc
Version: 4.5.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: middle-end
AssignedTo: unassig...@gcc.gnu.org
ReportedBy: jay.kr...@cornell.edu
fold_binary seemingly changes the types of division inputs (but not the
output),
leading to configure -enable-checking to fail.
My code is something like this (using a different frontend
and slightly patched 4.5.1 but I don't think relevantly):
long a;
long F(void)
{
return a / a;
}
configure -enable-checking=fold,...:
gcc-4.5
fold-const.c
fold_binary_loc(code = FLOOR_DIV_EXPR,
op0, op1, type all int_64
arg0, arg1 become word_64
(not op0, op1, but arg0, arg1)
and then we end up here:
if ((code == CEIL_DIV_EXPR || code == FLOOR_DIV_EXPR)
&& multiple_of_p (type, arg0, arg1))
return fold_build2_loc (loc, EXACT_DIV_EXPR, type, arg0, arg1);
and then:
error: type mismatch in binary expression
int_64
word_64
word_64
D.1003 = D.1001 /[ex] D.1002;
multiple_of_p is true because the operands are the same.
(This would optimize to 1, unless the operands might be 0.)
I'll see if I can reproduce with unpatched C 4.5.1 and trunk.
- Jay
