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From: "Kei Sakamoto" <sakamoto.kei@renesas.com>
To: "Daniel Jacobowitz" <drow@false.org>
Cc: <gdb-patches@sources.redhat.com>
Subject: Re: [RFA/m32r] Fix breakpoint bug
Date: Tue, 26 Oct 2004 05:45:00 -0000	[thread overview]
Message-ID: <002001c4bb1f$20031630$5169910a@E5A02646> (raw)
In-Reply-To: <20041025153816.GA28488@nevyn.them.org>

> I'm curious about the little endian case:
> 
> +  else /* little-endian */
> +    {
> +      if ((addr & 3) == 0)
> + {
> +   buf[0] = contents_cache[0];
> +   buf[1] = contents_cache[1] & 0x7f;
> +   buf[2] = bp_entry[1];
> +   buf[3] = bp_entry[0];
>   }
> 
> Shouldn't the breakpoint be placed at buf[0] here rather than buf[2]?

For most of architectures - yes, it shold be at buf[0]. But the little endian
mode of M32R is a kind of unique.

In other architectures, two 16-bit instructions, A and B, are placed as
the following:

Big endian:
A0 A1 B0 B1

Little endian:
A1 A0  B1 B0

In M32R, they are placed like this:

Big endian:
A0 A1 B0 B1

Little endian:
B1 B0 A1 A0

This is because M32R always fetches instructions in 32-bit.
So the breakpoint should be placed at buf[2].

Kei Sakamoto


  reply	other threads:[~2004-10-26  5:45 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2004-10-07  6:32 Kei Sakamoto
2004-10-18  6:43 ` [RFA/m32r] Unreviewed patch (breakpoint bug) Kei Sakamoto
2004-10-25  9:02   ` Kei Sakamoto
2004-11-01  1:08     ` Kei Sakamoto
2004-10-25 16:19 ` [RFA/m32r] Fix breakpoint bug Daniel Jacobowitz
2004-10-26  5:45   ` Kei Sakamoto [this message]
2004-11-04  0:21     ` Andrew Cagney
2004-11-04  0:50       ` Kei Sakamoto

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