[ruby-cvs:78699] f47c38245f (master): gc.h: Add SET_MACHINE_STACK_END specific for Powerpc64 (#1767)

Breno Leitao	2019-12-16 10:05:21 +0900 (Mon, 16 Dec 2019)

  New Revision: f47c38245f

  https://github.com/ruby/ruby/commit/f47c38245f

  Log:
    gc.h: Add SET_MACHINE_STACK_END specific for Powerpc64 (#1767)
    
    Currently we are not able to grab the correct end/top of the stack on
    powerpc64 due to the fact that it uses the fallback function.
    
    The fallback function does not return the correct top of the stack
    because it adds a new frame and the returned top of the stack contains
    this frame overhead that could be something around 112 bytes on
    Powerpc64.
    
    This patch simply gets the correct top of the stack pointer, which is
    always on r1 register according to both ABI v1 and ABI v2 (Little
    endian).
    
    Signed-off-by: Breno Leitao <[email protected]>

  Modified files:
    gc.h