On Thu, Aug 15, 2013 at 11:21 AM, Yufeng Zhang <yufeng.zh...@arm.com> wrote: > Ping^4~ > > I am aware that it is currently holiday season, but it would be really nice > if this tiny patch can get some further comments even if it is not an > approval. > > The original RFA email is here: > http://gcc.gnu.org/ml/gcc-patches/2013-06/msg01485.html
>From my point of view it is correct after understanding the ABI better though I cannot approve it. Thanks, Andrew Pinski > > Regards, > Yufeng > > > On 07/18/13 11:28, Yufeng Zhang wrote: >> >> Ping^3~ >> >> Thanks, >> Yufeng >> >> On 07/08/13 11:11, Yufeng Zhang wrote: >>> >>> Ping^2~ >>> >>> Thanks, >>> Yufeng >>> >>> >>> On 07/02/13 23:44, Yufeng Zhang wrote: >>>> >>>> Ping~ >>>> >>>> Can I get an OK please if there is no objection? >>>> >>>> Regards, >>>> Yufeng >>>> >>>> On 06/26/13 23:39, Yufeng Zhang wrote: >>>>> >>>>> This patch updates assign_parm_find_data_types to assign passed_mode >>>>> and >>>>> nominal_mode with the mode of the built pointer type instead of the >>>>> hard-coded Pmode in the case of pass-by-reference. This is in line >>>>> with >>>>> the assignment to passed_mode and nominal_mode in other cases inside >>>>> the >>>>> function. >>>>> >>>>> assign_parm_find_data_types generally uses TYPE_MODE to calculate >>>>> passed_mode and nominal_mode: >>>>> >>>>> /* Find mode of arg as it is passed, and mode of arg as it >>>>> should be >>>>> during execution of this function. */ >>>>> passed_mode = TYPE_MODE (passed_type); >>>>> nominal_mode = TYPE_MODE (nominal_type); >>>>> >>>>> this includes the case when the passed argument is a pointer by itself. >>>>> >>>>> However there is a discrepancy when it deals with argument passed by >>>>> invisible reference; it builds the argument's corresponding pointer >>>>> type, but sets passed_mode and nominal_mode with Pmode directly. >>>>> >>>>> This is OK for targets where Pmode == ptr_mode, but on AArch64 with >>>>> ILP32 they are different with Pmode as DImode and ptr_mode as SImode. >>>>> When such a reference is passed on stack, the reference is prepared by >>>>> the caller in the lower 4 bytes of an 8-byte slot but is fetched by the >>>>> callee as an 8-byte datum, of which the higher 4 bytes may contain >>>>> junk. >>>>> It is probably the combination of Pmode != ptr_mode and the >>>>> particular >>>>> ABI specification that make the AArch64 ILP32 the first target on which >>>>> the issue manifests itself. >>>>> >>>>> Bootstrapped on x86_64-none-linux-gnu. >>>>> >>>>> OK for the trunk? >>>>> >>>>> Thanks, >>>>> Yufeng >>>>> >>>>> >>>>> gcc/ >>>>> * function.c (assign_parm_find_data_types): Set passed_mode and >>>>> nominal_mode to the TYPE_MODE of nominal_type for the built >>>>> pointer type in case of the struct-pass-by-reference. >>>> >>>> >>>> >>>> >>> >>> >>> >> >> >> > >
