http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49472
--- Comment #10 from Eric Botcazou <ebotcazou at gcc dot gnu.org> 2011-06-21 08:31:22 UTC --- > --- gcc/simplify-rtx.c.jj 2011-06-08 08:53:15.000000000 +0200 > +++ gcc/simplify-rtx.c 2011-06-21 09:46:27.000000000 +0200 > @@ -686,13 +686,13 @@ simplify_unary_operation_1 (enum rtx_cod > return simplify_gen_binary (MINUS, mode, temp, XEXP (op, 1)); > } > > - /* (neg (mult A B)) becomes (mult (neg A) B). > + /* (neg (mult A B)) becomes (mult A (neg B)). > This works even for floating-point values. */ > if (GET_CODE (op) == MULT > && !HONOR_SIGN_DEPENDENT_ROUNDING (mode)) > { > - temp = simplify_gen_unary (NEG, mode, XEXP (op, 0), mode); > - return simplify_gen_binary (MULT, mode, temp, XEXP (op, 1)); > + temp = simplify_gen_unary (NEG, mode, XEXP (op, 1), mode); > + return simplify_gen_binary (MULT, mode, XEXP (op, 0), temp); > } > > /* NEG commutes with ASHIFT since it is multiplication. Only do > > stops the moving of the operands around, with this it keeps being called with > the same operands again and again, but still an endless recursion. Eric, any > preferences where to prevent this from happening? ISTM that pursuing in the above way, according to swap_commutative_operands_p, is a sensible approach, so I'd remove the simplify_binary_operation_1 bits.