using scratchpads to enhance RTL-level if-conversion: revised patch

[Richard Henderson]

On 10/14/2015 12:05 PM, Richard Henderson wrote:
> If you're using one of the switches that checks for stack overflow at the start
> of the function, you certainly don't want to do any such stores.

Oh, and for a given target the kernel may consider any write to the stack vma 
below the stack pointer as invalid.

The x86 kernels will at least handle "enter $65535, $31", which can write to a 
bit more than 64k below %esp before %esp gets updated, but that's probably not 
going to be true of most risc targets.


r~