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. 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)); >