[llvm-commits] [cfe-commits] Fix bug 11753 - Incorrect code generated for 64bit types on ARM

[Bob Wilson]

The old APCS ABI does not require aligned register pairs for i64 values.

On Mar 30, 2012, at 1:01 PM, Weiming Zhao wrote:

> Hi Sandeep,
> 
> I can't find the spec for aps-gnu. But my tests show that, in term of
> passing i64, it requires an aligned register pair, which is the same
> requirement in aapcs. 
> This why I mentions the aapcs spec. 
> 
> Thanks,
> Weiming
> 
> 
> -----Original Message-----
> From: Sandeep Patel [mailto:deeppatel1987 at gmail.com]
> Sent: Thursday, March 29, 2012 6:17 PM
> To: Weiming Zhao
> Cc: "'cfe-commits at cs.uiuc.edu.'"@pps04.cites.illinois.edu;
> llvm-commits at cs.uiuc.edu
> Subject: Re: [llvm-commits] Fix bug 11753 - Incorrect code generated for
> 64bit types on ARM
> 
> You're testing apcs-gnu, but referring to the aapcs spec.
> 
> i64 parameter alignment should already be handled by the CCIfAlign<> parts
> of ARMCallingConv.td in the backend for AAPCS.
> 
> deep
> 
> On Thu, Mar 29, 2012 at 9:22 PM, Weiming Zhao <weimingz at codeaurora.org>
> wrote:
>> Hello,
>> 
>> 
>> 
>> This is a bug fix for Clang. It fixes bug 11753 - Incorrect code 
>> generated for 64bit types on ARM.
>> 
>> 
>> 
>> ARM calling convention requires a double-word sized type is passed in 
>> two consecutive registers (r0,r1 or r2,r3). (See 
>> http://infocenter.arm.com/help/topic/com.arm.doc.ihi0042d/IHI0042D_aap
>> cs.pdf
>> 5.1.1.1, page 16).
>> 
>> 
>> 
>> However, currently, for apcs-gnu ABI, such constraint has not been 
>> implemented.
>> 
>> 
>> 
>> This patch fixes this issue by padding a register if needed. This 
>> solution is similar to a recent fix for MIPS.
>> 
>> 
>> 
>> I’m attaching my patch
>> (0001-Fix-the-missed-register-padding-for-passing-long-lon.patch), a 
>> new unit test case (0002-unnit-test.patch), as well as the running 
>> results of unit test (unit_test_after.txt) and the test suite 
>> (testsuite.report.simple.txt).  My patch doesn’t cause any errors.
>> 
>> 
>> 
>> I also uploaded the same files to the bugzilla.
>> 
>> 
>> 
>> Please kindly review the codes.
>> 
>> 
>> 
>> Thanks,
>> 
>> Weiming
>> 
>> 
>> 
>> 
>> 
>> 
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>> 
> 
> 
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