Reid Kleckner d0145262e2 Re-land r335297 "[X86] Implement more of x86-64 large and medium PIC code models" ... The large code model allows code and data segments to exceed 2GB, which means that some symbol references may require a displacement that cannot be encoded as a displacement from RIP. The large PIC model even relaxes the assumption that the GOT itself is within 2GB of all code. Therefore, we need a special code sequence to materialize it: .LtmpN: leaq .LtmpN(%rip), %rbx movabsq $_GLOBAL_OFFSET_TABLE_-.LtmpN, %rax # Scratch addq %rax, %rbx # GOT base reg From that, non-local references go through the GOT base register instead of being PC-relative loads. Local references typically use GOTOFF symbols, like this: movq extern_gv@GOT(%rbx), %rax movq local_gv@GOTOFF(%rbx), %rax All calls end up being indirect: movabsq $local_fn@GOTOFF, %rax addq %rbx, %rax callq *%rax The medium code model retains the assumption that the code segment is less than 2GB, so calls are once again direct, and the RIP-relative loads can be used to access the GOT. Materializing the GOT is easy: leaq _GLOBAL_OFFSET_TABLE_(%rip), %rbx # GOT base reg DSO local data accesses will use it: movq local_gv@GOTOFF(%rbx), %rax Non-local data accesses will use RIP-relative addressing, which means we may not always need to materialize the GOT base: movq extern_gv@GOTPCREL(%rip), %rax Direct calls are basically the same as they are in the small code model: They use direct, PC-relative addressing, and the PLT is used for calls to non-local functions. This patch adds reasonably comprehensive testing of LEA, but there are lots of interesting folding opportunities that are unimplemented. I restricted the MCJIT/eh-lg-pic.ll test to Linux, since the large PIC code model is not implemented for MachO yet. Differential Revision: https://reviews.llvm.org/D47211 llvm-svn: 335508		2018-06-25 18:16:27 +00:00
..
__init__.py
asm.py	Re-land r335297 "[X86] Implement more of x86-64 large and medium PIC code models"	2018-06-25 18:16:27 +00:00
common.py	[Utils][X86] Help update_llc_test_checks.py to recognise retl/retq to reduce CHECK duplication (PR35003)	2018-06-01 13:37:01 +00:00