Joerg Sonnenberger via llvm-dev
2017-Jan-09 11:45 UTC
[llvm-dev] RFC: Dynamically Allocated "Callee Saved Registers" Lists
On Mon, Jan 09, 2017 at 12:47:07PM +0300, Bruce Hoult via llvm-dev wrote:> Is there any calling convention, on any supported platform, that requires > the callee to preserve a register that was used to pass an argument?The "this" parameter for constructors and possible other things is handled like that on some platforms. ARM EABI I think? Joerg
David Chisnall via llvm-dev
2017-Jan-09 11:58 UTC
[llvm-dev] RFC: Dynamically Allocated "Callee Saved Registers" Lists
On 9 Jan 2017, at 11:45, Joerg Sonnenberger via llvm-dev <llvm-dev at lists.llvm.org> wrote:> > On Mon, Jan 09, 2017 at 12:47:07PM +0300, Bruce Hoult via llvm-dev wrote: >> Is there any calling convention, on any supported platform, that requires >> the callee to preserve a register that was used to pass an argument? > > The "this" parameter for constructors and possible other things is > handled like that on some platforms. ARM EABI I think?Do you model that as a callee-save register, or as a register that is both an argument and return register and is guaranteed to return the argument? David
Joerg Sonnenberger via llvm-dev
2017-Jan-09 12:31 UTC
[llvm-dev] RFC: Dynamically Allocated "Callee Saved Registers" Lists
On Mon, Jan 09, 2017 at 11:58:07AM +0000, David Chisnall wrote:> On 9 Jan 2017, at 11:45, Joerg Sonnenberger via llvm-dev <llvm-dev at lists.llvm.org> wrote: > > > > On Mon, Jan 09, 2017 at 12:47:07PM +0300, Bruce Hoult via llvm-dev wrote: > >> Is there any calling convention, on any supported platform, that requires > >> the callee to preserve a register that was used to pass an argument? > > > > The "this" parameter for constructors and possible other things is > > handled like that on some platforms. ARM EABI I think? > > Do you model that as a callee-save register, or as a register that is > both an argument and return register and is guaranteed to return the > argument?I think it is currently modeled as return register with guaranteed value. Joerg