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Re: [PATCH] testsuite/gdb.dwarf2: Fix for dw2-ifort-parameter failure on ARM

From: Yao Qi <yao at codesourcery dot com>
To: Omair Javaid <omair dot javaid at linaro dot org>
Cc: <gdb-patches at sourceware dot org>
Date: Tue, 16 Jul 2013 10:52:55 +0800
Subject: Re: [PATCH] testsuite/gdb.dwarf2: Fix for dw2-ifort-parameter failure on ARM
References: <CANW4E-2bQYjx6YdR3qGyKUsQa_KOrtmkWsZYqKzcuQBF==RPpw at mail dot gmail dot com> <CANW4E-25HdXYKMk258iO=GZ=PNM=Zu4jMbstpkSoMgE9wFpmkQ at mail dot gmail dot com>

On 07/15/2013 06:25 PM, Omair Javaid wrote:

gdb.dwarf2/dw2-ifort-parameter fails on ARM because the dwarf2 debug
information being created by gdb.dwarf2/dw2-ifort-parameter-debug.S
gets corrupted because LSB of function addresses is ON in Thumb mode.
ARM instructions are word aligned and LSB of instruction address is
used to determine whether code being branched to is Thumb or ARM code.
This patch solves the problem by decrementing function address by one
in thumb mode. This patch has been tested on x86_64 and arm7 machines.


Omair,

IMO, the last bit of "function pointer value" indicates whether thetarget function is an ARM or a thumb one. The "address" should stillrefer to the actual address, as "DWARF should tell the truth". What iswrong *without* your patch?


--
Yao (éå)

References:
- [PATCH] testsuite/gdb.dwarf2: Fix for dw2-ifort-parameter failure on ARM
  - From: Omair Javaid

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