> Tested on x86_64-linux-gnu, mipsisa32-elf and mipsisa64-elf. Also tested
> by making sure that there were no code differences for a set of gcc .ii
> files on gcc20 (-O2 -march=native). OK to install?
Are you sure that generating TRUNCATEs out of nowhere in simplify_subreg is
always correct?
> gcc/
> * machmode.h (GET_MODE_UNIT_PRECISION): New macro.
> * simplify-rtx.c (simplify_truncation): New function.
You should say where it comes from.
> (simplify_unary_operation_1): Use it. Remove sign bit test
> for !TRULY_NOOP_TRUNCATION_MODES_P.
(simplify_unary_operation_1) <TRUNCATE>: ...
> (simplify_subreg): Use simplify_int_lowpart for TRUNCATE.
This function doesn't exist. And this is misleading, it's not just for
TRUNCATE, it's for a truncation to the lowpart.
> /* Try to simplify a unary operation CODE whose output mode is to be
> MODE with input operand OP whose mode was originally OP_MODE.
> Return zero if no simplification can be made. */
> @@ -689,12 +850,6 @@ simplify_unary_operation_1 (enum rtx_cod
> op_mode = mode;
> in2 = simplify_gen_unary (NOT, op_mode, in2, op_mode);
>
> - if (GET_CODE (in2) == NOT && GET_CODE (in1) != NOT)
> - {
> - rtx tem = in2;
> - in2 = in1; in1 = tem;
> - }
> -
> return gen_rtx_fmt_ee (GET_CODE (op) == IOR ? AND : IOR,
> mode, in1, in2);
> }
Why is this hunk here?
> @@ -5595,14 +5730,6 @@ simplify_subreg (enum machine_mode outer
> return NULL_RTX;
> }
>
> - /* Merge implicit and explicit truncations. */
> -
> - if (GET_CODE (op) == TRUNCATE
> - && GET_MODE_SIZE (outermode) < GET_MODE_SIZE (innermode)
> - && subreg_lowpart_offset (outermode, innermode) == byte)
> - return simplify_gen_unary (TRUNCATE, outermode, XEXP (op, 0),
> - GET_MODE (XEXP (op, 0)));
> -
> /* SUBREG of a hard register => just change the register number
> and/or mode. If the hard register is not valid in that mode,
> suppress this simplification. If the hard register is the stack,
Likewise.
--
Eric Botcazou
