On Tue, 21 Jul 2015, Kyrill Tkachov wrote: > > On 21/07/15 08:24, Richard Biener wrote: > > On Mon, 20 Jul 2015, Kyrill Tkachov wrote: > > > > > Hi all, > > > > > > This patch fixes the PR in question which is a miscompilation of > > > gcc.dg/fixed-point/unary.c on arm. > > > It just restricts the A - B -> A + (-B) transformation when the type is > > > fixed-point. > > > > > > This fixes the testcase for me. > > > Is this the right approach? > > > > > > Bootstrap and test on arm and x86 running. > > > > > > Ok if testing is clean? > > Ok, but I think the fold-const.c code has the same issue, no: > > > > /* A - B -> A + (-B) if B is easily negatable. */ > > if (negate_expr_p (arg1) > > && !TYPE_OVERFLOW_SANITIZED (type) > > && ((FLOAT_TYPE_P (type) > > /* Avoid this transformation if B is a positive REAL_CST. > > */ > > && (TREE_CODE (arg1) != REAL_CST > > || REAL_VALUE_NEGATIVE (TREE_REAL_CST (arg1)))) > > || INTEGRAL_TYPE_P (type))) > > return fold_build2_loc (loc, PLUS_EXPR, type, > > fold_convert_loc (loc, type, arg0), > > fold_convert_loc (loc, type, > > negate_expr (arg1))); > > > > ah, no. The above only applies to float-type and integral-types. > > > > Thus yes, your patch is ok. Can you double-check the other pattern, > > > > /* -(A + B) -> (-B) - A. */ > > (simplify > > (negate (plus:c @0 negate_expr_p@1)) > > (if (!HONOR_SIGN_DEPENDENT_ROUNDING (element_mode (type)) > > && !HONOR_SIGNED_ZEROS (element_mode (type))) > > (minus (negate @1) @0))) > > > > ? > > Thanks, committed with r226028. > I can add (FLOAT_TYPE_P (type) || INTEGRAL_TYPE_P (type)) to the condition. > That would more closely mirror the original logic, right? > That passes x86_64 bootstrap and aarch64 testing looks ok.
Yeah, that works for me, too. Thanks, Richard.
