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Re: Restore m68k bootstrap
- From: Richard Biener <richard dot guenther at gmail dot com>
- To: Marc Glisse <marc dot glisse at inria dot fr>
- Cc: gcc-patches at gcc dot gnu dot org
- Date: Tue, 14 May 2013 13:26:21 +0200
- Subject: Re: Restore m68k bootstrap
- References: <alpine dot DEB dot 2 dot 02 dot 1305141316560 dot 6987 at stedding dot saclay dot inria dot fr>
On Tue, May 14, 2013 at 1:23 PM, Marc Glisse <marc.glisse@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.glisse@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));
>