Cced maintainer like David Edelsohn and Segher Boessenkool .
Any suggestions/comments for the below query ?
Thank you
~Umesh
On Thu, Oct 25, 2018 at 9:23 PM Umesh Kalappa <umesh.kalap...@gmail.com> wrote:
>
> Hi All,
>
> For the below code (test.c)
>
> int foo()
> {
> printf("Hello World");
> }
>
> On linux :
> ccpc -mcpu=e6500 -mno-altivec -mabi=no-altivec -D_WRS_HARDWARE_FP
> -mabi=elfv2 -mcmodel=med -mhard-float -S test.c
>
> linux asm :
> the constant string fetched like
>
> addis 3,2,.LC0@toc@ha
> addi 3,3,.LC0@toc@l
>
> where offset signed 32 bit used relatively to toc base on linux as
> expected for the medium code model .
> and the relocation entry will be generated by gas :
> R_PPC64_TOC16_HA and R_PPC64_TOC16_LO
>
> For Windows :
>
> same command and windows asm looks like
>
> la 3,.LC0@toc(2)
>
> where offset used signed 16 bit used relatively to toc base why it so ?.
> and the relocation entry will be :
> R_PPC64_TOC16 (signed 16 bit offset )
>
> why this difference and when we greping the .md file and we found
> patterns (rs6000.md ) like
>
> ;; Largetoc support
> (define_insn "*largetoc_high"
> [(set (match_operand:DI 0 "gpc_reg_operand" "=b*r")
> (high:DI
> (unspec [(match_operand:DI 1 "" "")
> (match_operand:DI 2 "gpc_reg_operand" "b")]
> UNSPEC_TOCREL)))]
> "TARGET_ELF && TARGET_CMODEL != CMODEL_SMALL"
> "addis %0,%2,%1@toc@ha")
>
> (define_insn "*largetoc_high_aix<mode>"
> [(set (match_operand:P 0 "gpc_reg_operand" "=b*r")
> (high:P
> (unspec [(match_operand:P 1 "" "")
> (match_operand:P 2 "gpc_reg_operand" "b")]
> UNSPEC_TOCREL)))]
> "TARGET_XCOFF && TARGET_CMODEL != CMODEL_SMALL"
> "addis %0,%1@u(%2)")
>
> the above patterns answered the difference b/w windows and linux .
>
> Questions to the expert is that using the medium code model ,how we
> can get the same linux semantics on windows (without source code
> changes) ?
>
> or above distinguish patterns for a reason and which we are missing here ?
>
> Thank you and awaiting for any comments
> ~Umesh
