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From: Bastian Koppelmann <kbastian@mail.uni-paderborn.de>
To: Rafael Kioji <rafaelkioji@gmail.com>, qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] Difference between tcg_gen_ld_i64 and tcg_gen_qemu_ld_i64.
Date: Sun, 29 Apr 2018 13:18:50 +0200	[thread overview]
Message-ID: <7a5d09e7-3e30-3683-41ae-076bd4532786@mail.uni-paderborn.de> (raw)
In-Reply-To: <7366cfc5-e37f-483d-917b-2aae41d1e59e@gmail.com>

On 04/29/2018 12:15 PM, Rafael Kioji wrote:
> Dear all,
> 
> What is the difference between these two functions? They are located in the file
> "tcg/tcg-op.c". Here is their header:
> 
> 1. static inline void tcg_gen_ld_i64(TCGv_i64 ret, TCGv_ptr arg2,
>    tcg_target_long offset)

This is used to access fields of qemu data structures from generated code, e.g.
CPUArmState.

> 2. void tcg_gen_qemu_ld_i64(TCGv_i64 val, TCGv addr, TCGArg idx,
>    TCGMemOp memop)

This actually generates a load to guest memory.

> 
> I don't quite understand the need for function (1). Especially because it is
> usually passed "cpu_env" for arg2. Like in target/arm/translate-a64.c:595:

cpu_env is a pointer to CPUArmState.

Cheers,
Bastian

      reply	other threads:[~2018-04-29 11:19 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-29 10:15 [Qemu-devel] Difference between tcg_gen_ld_i64 and tcg_gen_qemu_ld_i64 Rafael Kioji
2018-04-29 11:18 ` Bastian Koppelmann [this message]

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