[X86] Tighten up a comment which confused x64 ABI terminology.
The x64 ABI has two major function types:
- frame functions
- leaf functions
A frame function is one which requires a stack frame. A leaf function
is one which does not. A frame function may or may not have a frame
pointer.
A leaf function does not require a stack frame and may never modify SP
except via a return (RET, tail call via JMP).
A frame function which has a frame pointer is permitted to use the LEA
instruction in the epilogue, a frame function without which doesn't
establish a frame pointer must use ADD to adjust the stack pointer epilogue.
Fun fact: Leaf functions don't require a function table entry
(associated PDATA/XDATA).
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@281006
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