From: Richard Henderson <rth@redhat.com>
To: Bernd Schmidt <bernds@codesourcery.com>
Cc: GCC Patches <gcc-patches@gcc.gnu.org>
Subject: Re: [2/11] Neater tests for signbits
Date: Tue, 05 Jul 2011 19:10:00 -0000 [thread overview]
Message-ID: <4E136149.2000802@redhat.com> (raw)
In-Reply-To: <4E0E03FF.2090405@codesourcery.com>
On 07/01/2011 10:29 AM, Bernd Schmidt wrote:
> * cse.c (find_comparison_args): Use val_mode_signbit_set_p.
> * simplify-rtx.c (mode_signbit_p): Use GET_MODE_PRECISION.
> (val_mode_signbit_p, val_mode_signbit_set_p): New functions.
> (simplify_const_unary_operation, simplify_binary_operation_1,
> simplify_const_binary_operation,
> simplify_const_relational_operation): Use them. Use
> GET_MODE_MASK for masking and sign-extensions.
> * combine.c (set_nonzero_bits_and_sign_copies, simplify_set,
> combine_simplify_rtx, force_to_mode, reg_nonzero_bits_for_combine,
> simplify_shift_const_1, simplify_comparison): Likewise.
> * expr.c (convert_modes): Likewise.
> * rtlanal.c (nonzero_bits1, canonicalize_condition): Likewise.
> * expmed.c (emit_cstore, emit_store_flag_1, emit_store_flag):
> Likewise.
> * rtl.h (val_mode_signbit_p, val_mode_signbit_set_p): Declare.
Ok, but,
> /* We must sign or zero-extend in this case. Start by
> zero-extending, then sign extend if we need to. */
> - val &= ((HOST_WIDE_INT) 1 << width) - 1;
> + val &= GET_MODE_MASK (oldmode);
> if (! unsignedp
> - && (val & ((HOST_WIDE_INT) 1 << (width - 1))))
> - val |= (HOST_WIDE_INT) (-1) << width;
> + && val_signbit_known_set_p (oldmode, val))
> + val |= ~GET_MODE_MASK (oldmode);
>
> return gen_int_mode (val, mode);
Shouldn't that sign-extension already be done by gen_int_mode?
There are at least 4 more copies of this idiom in your patch.
As a follow-up could you pull that out into a new function?
Perhaps signextend_int_mode, akin to gen_int_mode?
r~
next prev parent reply other threads:[~2011-07-05 19:09 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-07-01 17:26 [0/11] GET_MODE_PRECISION vs GET_MODE_BITSIZE Bernd Schmidt
2011-07-01 17:27 ` [1/11] Use targetm.shift_truncation_mask more consistently Bernd Schmidt
2011-07-04 15:29 ` Richard Henderson
2011-07-06 18:13 ` Richard Sandiford
2011-07-07 0:03 ` Bernd Schmidt
2011-07-07 8:07 ` Richard Sandiford
2011-07-01 17:30 ` [2/11] Neater tests for signbits Bernd Schmidt
2011-07-05 19:10 ` Richard Henderson [this message]
2011-07-05 21:35 ` Bernd Schmidt
2011-07-01 17:30 ` [3/11] Remove some dead code Bernd Schmidt
2011-07-05 19:12 ` Richard Henderson
2011-07-01 17:32 ` [4/11] Use precisions for TRULY_NOOP_TRUNCATION Bernd Schmidt
2011-07-05 19:16 ` Richard Henderson
2011-07-01 17:33 ` [5/11] Neater tests for paradoxical subregs Bernd Schmidt
2011-07-05 19:19 ` Richard Henderson
2011-07-01 17:34 ` [6/11] Tests for HOST_WIDE_INT representability Bernd Schmidt
2011-07-05 19:19 ` Richard Henderson
2011-07-01 17:36 ` [7/11] rtl optimizer changes Bernd Schmidt
2011-07-06 18:25 ` Richard Henderson
2011-07-01 17:37 ` [8/11] Expander changes Bernd Schmidt
2011-07-06 18:26 ` Richard Henderson
2011-07-01 17:38 ` [9/11] Fix units mismatch in comparison Bernd Schmidt
2011-07-06 18:27 ` Richard Henderson
2011-07-01 17:41 ` [10/11] Expander fixes for 40-bit integers Bernd Schmidt
2011-07-06 18:37 ` Richard Henderson
2011-07-01 17:42 ` [11/11] Fix get_mode_bounds Bernd Schmidt
2011-07-06 18:38 ` Richard Henderson
2011-07-06 23:16 ` Bernd Schmidt
2011-07-06 23:39 ` Richard Henderson
2011-07-11 10:38 ` Bernd Schmidt
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