From: Thiemo Seufer <ths@networkno.de>
To: Amarnath <amarnath@acmet.com>
Cc: binutils@sourceware.org
Subject: Re: Is it possible to branch to an absolute address ?
Date: Fri, 07 Jul 2006 10:10:00 -0000 [thread overview]
Message-ID: <20060707100952.GD4274@networkno.de> (raw)
In-Reply-To: <200607070954.k679sUO28216@alice.acmet.com>
Amarnath wrote:
> HI,
>
> I have a query in my mind. Please check the following sample assembly file:
>
> ----------- Snip ---------------
>
> .file 1 "TestingBranch.c"
> .set mips16
>
> gcc2_compiled.:
> __gnu_compiled_c:
> .text
> .align 2
> .globl func
>
> .align 2
> .globl main
> .ent main
> main:
> .frame $17,16,$31 # vars= 8, regs= 2/0, args= 0,
> extra= 0
> .mask 0x80020000,-4
> .fmask 0x00000000,0
>
> b 0x4000 # >>> branch with absolute operand
> move $sp,$17
> $L2:
> .end main
>
> .ent func
> func:
> .frame $17,16,$31 # vars= 8, regs= 1/0,
> args= 0, extra= 0
> .mask 0x00020000,-8
> .fmask 0x00000000,0
>
> $L1:
>
> .end func
>
> -------------- End Snip ----------------
>
> - In the above, why GCC was not assembling the branch instruction with
> absolute value as operand in it?
Can you also provide the C source code? I fail to see how C code could
result in such assembly.
> - Is there any restriction in branching towards absolute value in ELF?
The MIPS architecture defines branches as PC relative. For an absolute
address you need a jump.
Thiemo
next prev parent reply other threads:[~2006-07-07 10:10 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-07-07 9:46 Amarnath
2006-07-07 10:10 ` Thiemo Seufer [this message]
2006-07-07 23:26 ` Eric Christopher
2006-07-08 4:54 ` Amarnath
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