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Re: [PATCH, PR 57748] Check for out of bounds access
- From: Richard Biener <richard dot guenther at gmail dot com>
- To: Bernd Edlinger <bernd dot edlinger at hotmail dot de>
- Cc: Martin Jambor <mjambor at suse dot cz>, GCC Patches <gcc-patches at gcc dot gnu dot org>
- Date: Tue, 17 Sep 2013 12:00:18 +0200
- Subject: Re: [PATCH, PR 57748] Check for out of bounds access
- Authentication-results: sourceware.org; auth=none
- References: <DUB122-W396D54115D70C9FF68A8D2E43C0 at phx dot gbl> <CAFiYyc13uxba37WySOxXf14UVJW15_DM7jggNGbR4H2cK96Eiw at mail dot gmail dot com> <DUB122-W323D4AAAEA1AFA890BF243E43C0 at phx dot gbl> <CAFiYyc13wC0jmZ4xELAiL5L5Sbh0yauZWViP2hTdR+H4s0iPSw at mail dot gmail dot com> <DUB122-W4D571A91831593BA22438E43C0 at phx dot gbl> <CAFiYyc1ECAdBJTkcziSL_f9SQyYUPY9k19QWqkN+RfLO=i2zaQ at mail dot gmail dot com> <20130910193228 dot GE6732 at virgil dot suse> <DUB122-W22DAEEE94B5ED3308F6967E4390 at phx dot gbl> <CAFiYyc3AHggjJbEmZvC_fh67o+LVpTBRdwyUv8T6EhQFE2vNWQ at mail dot gmail dot com> <DUB122-W281E996A4885309956418EE4250 at phx dot gbl>
On Sun, Sep 15, 2013 at 6:55 PM, Bernd Edlinger
> Hello Richard,
> attached is my second attempt at fixing PR 57748. This time the movmisalign
> path is completely removed and a similar bug in the read handling of misaligned
> structures with a non-BLKmode is fixed too. There are several new test cases for the
> different possible failure modes.
> This patch was boot-strapped and regression tested on x86_64-unknown-linux-gnu
> and i686-pc-linux-gnu.
> Additionally I generated eCos and an eCos-application (on ARMv5 using packed
> structures) with an arm-eabi cross compiler, and looked for differences in the
> disassembled code with and without this patch, but there were none.
> OK for trunk?
I agree that the existing movmisaling path that you remove is simply bogus, so
removing it looks fine to me. Can you give rationale to
@@ -4773,6 +4738,8 @@ expand_assignment (tree to, tree from, b
if (MEM_P (to_rtx)
&& GET_MODE (to_rtx) == BLKmode
&& GET_MODE (XEXP (to_rtx, 0)) != VOIDmode
+ && bitregion_start == 0
+ && bitregion_end == 0
&& bitsize > 0
&& (bitpos % bitsize) == 0
&& (bitsize % GET_MODE_ALIGNMENT (mode1)) == 0
and especially to
@@ -9905,7 +9861,7 @@ expand_expr_real_1 (tree exp, rtx target
&& modifier != EXPAND_STACK_PARM
? target : NULL_RTX),
- modifier == EXPAND_SUM ? EXPAND_NORMAL : modifier);
/* If the bitfield is volatile, we want to access it in the
field's mode, not the computed mode.
which AFAIK makes "memory" expansion of loads/stores from/to registers
change (fail? go through stack memory?) - see handling of non-MEM return
values from that expand_expr call.
That is, do you see anything break with just removing the movmisalign path?
I'd rather install that (with the new testcases that then pass) separately as
this is a somewhat fragile area and being able to more selectively
would be nice.