Hi Segher , >>What did you expect, what happened instead? For example the complex args are passed in GPR's for cexp in the case GCC and Clang uses caller memory .
for reference : https://godbolt.org/z/MfMz3cTe7 We have cross tools like some of libraries built using the GCC and some use Clang . We approached Clang developers on this behaviour (Why stack , not the FPR's registers like PPC64) and they are not going to change this behaviour, and asked us to refer back to GCC ,hence this email thread. Question is : Why does GCC choose to use GPR's here and have any reference to support this decision ? Thank you ~Umesh On Tue, Jun 6, 2023 at 10:16 PM Segher Boessenkool <seg...@kernel.crashing.org> wrote: > > Hi! > > On Tue, Jun 06, 2023 at 08:35:22PM +0530, Umesh Kalappa wrote: > > Hi Adnrew, > > Thank you for the quick response and for PPC64 too ,we do have > > mismatches in ABI b/w complex operations like > > https://godbolt.org/z/bjsYovx4c . > > > > Any reason why GCC chose to use GPR 's here ? > > What did you expect, what happened instead? Why did you expect that, > and why then is it an error what did happen? > > You used -O0. As long as the code works, all is fine. But unoptimised > code frequently is hard to read, please use -O2 instead? > > As Andrew says, why did you use -m32 for GCC but -m64 for LLVM? It is > hard to compare those at all! 32-bit PowerPC Linux ABI (based on 32-bit > PowerPC ELF ABI from 1995, BE version) vs. 64-bit ELFv2 ABI from 2015 > (LE version). > > > Segher
