[PATCH] Do not generate a __morestack prologue, for functions with a stack of size zero

[Nadav Rotem]

Hi Florian, 

I am not that familiar with this code. Tim, can you please review this patch?

Thanks,
Nadav

On May 21, 2014, at 7:51 PM, Florian Zeitz <florob at babelmonkeys.de> wrote:

> Hi nadav,
> 
> When segmented stacks are used, this omits the usual __morestack prologue on functions that do not perform any stack allocations.
> This ought to be valid since these functions never need to grow the stack.
> This is particularly beneficial to small functions, where the prologue would otherwise outweigh the actual code.
> 
> http://reviews.llvm.org/D3863
> 
> Files:
>  lib/Target/ARM/ARMFrameLowering.cpp
>  lib/Target/X86/X86FrameLowering.cpp
>  test/CodeGen/ARM/segmented-stacks.ll
>  test/CodeGen/Thumb/segmented-stacks.ll
>  test/CodeGen/X86/segmented-stacks.ll
> <D3863.9675.patch>