From 247fe6aeab964e31cb03beba3cf3f6a2cb972c31 Mon Sep 17 00:00:00 2001 From: Reid Kleckner Date: Thu, 21 Jun 2018 21:55:08 +0000 Subject: [X86] Implement more of x86-64 large and medium PIC code models Summary: 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. Reviewers: chandlerc, echristo Subscribers: hiraditya, llvm-commits Differential Revision: https://reviews.llvm.org/D47211 llvm-svn: 335297 --- llvm/utils/UpdateTestChecks/asm.py | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) (limited to 'llvm/utils/UpdateTestChecks/asm.py') diff --git a/llvm/utils/UpdateTestChecks/asm.py b/llvm/utils/UpdateTestChecks/asm.py index 6bdaaa46ca5..0ece3e131f5 100644 --- a/llvm/utils/UpdateTestChecks/asm.py +++ b/llvm/utils/UpdateTestChecks/asm.py @@ -110,8 +110,9 @@ def scrub_asm_x86(asm, args): asm = SCRUB_X86_SPILL_RELOAD_RE.sub(r'{{[-0-9]+}}(%\1{{[sb]}}p)\2', asm) # Generically match the stack offset of a memory operand. asm = SCRUB_X86_SP_RE.sub(r'{{[0-9]+}}(%\1)', asm) - # Generically match a RIP-relative memory operand. - asm = SCRUB_X86_RIP_RE.sub(r'{{.*}}(%rip)', asm) + if getattr(args, 'x86_scrub_rip', False): + # Generically match a RIP-relative memory operand. + asm = SCRUB_X86_RIP_RE.sub(r'{{.*}}(%rip)', asm) # Generically match a LCP symbol. asm = SCRUB_X86_LCP_RE.sub(r'{{\.LCPI.*}}', asm) if getattr(args, 'extra_scrub', False): -- cgit v1.2.3