On Tue, 14 May 2013, Richard Biener wrote:
On Tue, May 14, 2013 at 1:23 PM, Marc Glisse <marc.gli...@inria.fr> wrote:
Hello,
in an earlier patch I apparently introduced a platform dependent signed /
unsigned comparison, so here is a fix. I am taking the chance to fix the
host_integerp second argument nearby: we want non-negative integers.
Passes bootstrap+testsuite on x86_64-linux-gnu and apparently bootstrap on
m68k.
2013-05-13 Marc Glisse <marc.gli...@inria.fr>
PR bootstrap/57266
* fold-const.c (fold_binary_loc) <shift>: Use an unsigned
variable for the shift amount. Check that we shift by non-negative
amounts.
--
Marc Glisse
Index: gcc/fold-const.c
===================================================================
--- gcc/fold-const.c (revision 198853)
+++ gcc/fold-const.c (working copy)
@@ -12416,27 +12416,27 @@ fold_binary_loc (location_t loc,
return fold_build2_loc (loc, code, type, op0, tem);
/* Since negative shift count is not well-defined,
don't try to compute it in the compiler. */
if (TREE_CODE (arg1) == INTEGER_CST && tree_int_cst_sgn (arg1) < 0)
return NULL_TREE;
prec = element_precision (type);
/* Turn (a OP c1) OP c2 into a OP (c1+c2). */
- if (TREE_CODE (op0) == code && host_integerp (arg1, false)
+ if (TREE_CODE (op0) == code && host_integerp (arg1, true)
&& TREE_INT_CST_LOW (arg1) < prec
- && host_integerp (TREE_OPERAND (arg0, 1), false)
+ && host_integerp (TREE_OPERAND (arg0, 1), true)
&& TREE_INT_CST_LOW (TREE_OPERAND (arg0, 1)) < prec)
That looks good, but ...
{
- HOST_WIDE_INT low = (TREE_INT_CST_LOW (TREE_OPERAND (arg0, 1))
- + TREE_INT_CST_LOW (arg1));
+ unsigned int low = (TREE_INT_CST_LOW (TREE_OPERAND (arg0, 1))
+ + TREE_INT_CST_LOW (arg1));
that's wrong. TREE_INT_CST_LOW doesn't fit in an unsigned int.
unsigned HOST_WIDE_INT would work though.
The checks above show that both TREE_INT_CST_LOW are smaller than prec
(for which I already used an unsigned int, but an unsigned char might have
been enough until Kenneth introduces int512_t). Do you still want the
change?
Ok with that change.
Thanks,
Richard.
/* Deal with a OP (c1 + c2) being undefined but (a OP c1) OP c2
being well defined. */
if (low >= prec)
{
if (code == LROTATE_EXPR || code == RROTATE_EXPR)
low = low % prec;
else if (TYPE_UNSIGNED (type) || code == LSHIFT_EXPR)
return omit_one_operand_loc (loc, type, build_zero_cst
(type),
TREE_OPERAND (arg0, 0));
--
Marc Glisse
