From: Richard Henderson <rth@twiddle.net>
To: Aurelien Jarno <aurelien@aurel32.net>, qemu-devel@nongnu.org
Cc: Paolo Bonzini <pbonzini@redhat.com>
Subject: Re: [Qemu-devel] [PATCH RFC 9/9] tcg: update README about size changing ops
Date: Fri, 17 Jul 2015 07:42:55 +0100 [thread overview]
Message-ID: <55A8A3EF.5070807@twiddle.net> (raw)
In-Reply-To: <1436958199-5181-10-git-send-email-aurelien@aurel32.net>
On 07/15/2015 12:03 PM, Aurelien Jarno wrote:
> +These ops are all optional in that case they are implemented as mov.
> +This is to allow some optimizations if the target maintains registers
> +zero or sign extended. For example a MIPS64 CPU requires that all
> +32-bit values are stored sign-extended in the registers. This means
> +the trunc_shr_i64_i32 should sign-extend the value when moving it
> +from a 64-bit to a 32-bit register. It also means ext_i32_i64 can be
> +implemented as a simple mov as the value is already sign extended.
We need better wording. Each one of the three are optional, and the other two
must be implemented. I think we ought to have a check in tcg.c about this, in
tcg_add_target_add_op_defs.
r~
prev parent reply other threads:[~2015-07-17 6:43 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-07-15 11:03 [Qemu-devel] [PATCH RFC 0/9] tcg: improve size changing ops Aurelien Jarno
2015-07-15 11:03 ` [Qemu-devel] [PATCH RFC 1/9] tcg: rename trunc_shr_i32 into trunc_shr_i64_i32 Aurelien Jarno
2015-07-17 6:14 ` Richard Henderson
2015-07-15 11:03 ` [Qemu-devel] [PATCH RFC 2/9] tcg: don't abuse TCG type in tcg_gen_trunc_shr_i64_i32 Aurelien Jarno
2015-07-17 6:14 ` Richard Henderson
2015-07-15 11:03 ` [Qemu-devel] [PATCH RFC 3/9] tcg: implement real ext_i32_i64 and extu_i32_i64 ops Aurelien Jarno
2015-07-17 6:19 ` Richard Henderson
2015-07-15 11:03 ` [Qemu-devel] [PATCH RFC 4/9] tcg/optimize: add optimizations for " Aurelien Jarno
2015-07-17 6:23 ` Richard Henderson
2015-07-15 11:03 ` [Qemu-devel] [PATCH RFC 5/9] tcg/i386: implement " Aurelien Jarno
2015-07-15 11:03 ` [Qemu-devel] [PATCH RFC 6/9] tcg/i386: document the way 32/64-bit conversions are handled Aurelien Jarno
2015-07-15 11:03 ` [Qemu-devel] [PATCH RFC 7/9] tcg: replace ext/u_i32_i64 by a mov when not implemented Aurelien Jarno
2015-07-17 6:30 ` Richard Henderson
2015-07-15 11:03 ` [Qemu-devel] [PATCH RFC 8/9] tcg/optimize: do not simplify size changing moves Aurelien Jarno
2015-07-17 6:38 ` Richard Henderson
2015-07-17 10:33 ` Aurelien Jarno
2015-07-18 7:24 ` Richard Henderson
2015-07-18 21:19 ` Aurelien Jarno
2015-07-15 11:03 ` [Qemu-devel] [PATCH RFC 9/9] tcg: update README about size changing ops Aurelien Jarno
2015-07-17 6:42 ` Richard Henderson [this message]
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