llvm-project

7ef497b1 - x86_64: Fix calls to __morestack under the large code model.

x86_64: Fix calls to __morestack under the large code model. Under the large code model, we cannot assume that __morestack lives within 2^31 bytes of the call site, so we cannot use pc-relative addressing. We cannot perform the call via a temporary register, as the rax register may be used to store the static chain, and all other suitable registers may be either callee-save or used for parameter passing. We cannot use the stack at this point either because __morestack manipulates the stack directly. To avoid these issues, perform an indirect call via a read-only memory location containing the address. This solution is not perfect, as it assumes that the .rodata section is laid out within 2^31 bytes of each function body, but this seems to be sufficient for JIT. Differential Revision: http://reviews.llvm.org/D6787 llvm-svn: 225003