The current SystemZ back-end only supports the local-exec TLS access model.
This patch adds all required CodeGen support for the other TLS models, which
means in particular:
- Expand initial-exec TLS accesses by loading TLS offsets from the GOT
using @indntpoff relocations.
- Expand general-dynamic and local-dynamic accesses by generating the
appropriate calls to __tls_get_offset. Note that this routine has
a non-standard ABI and requires loading the GOT pointer into %r12,
so the patch also adds support for the GLOBAL_OFFSET_TABLE ISD node.
- Add a new platform-specific optimization pass to remove redundant
__tls_get_offset calls in the local-dynamic model (modeled after
the corresponding X86 pass).
- Add test cases verifying all access models and optimizations.
llvm-svn: 229654
Similar to r191364, but for calls. This patch also removes the shortening
of BRASL to BRAS within a TU. Doing that was a bit controversial internally,
since there's a strong expectation with the z assembler that WYWIWYG.
llvm-svn: 191366
GPR and FPR constraints like "{r2}" and "{f2}" weren't handled correctly
because the name-to-regno mapping depends on the value type and
(because of that) the internal names in RegStrings are not the
same as the AsmName.
CC constraints like "{cc}" didn't work either because there was no
associated register class.
llvm-svn: 186148
Before this change, the SystemZ backend would use BRCL for all branches
and only consider shortening them to BRC when generating an object file.
E.g. a branch on equal would use the JGE alias of BRCL in assembly output,
but might be shortened to the JE alias of BRC in ELF output. This was
a useful first step, but it had two problems:
(1) The z assembler isn't traditionally supposed to perform branch shortening
or branch relaxation. We followed this rule by not relaxing branches
in assembler input, but that meant that generating assembly code and
then assembling it would not produce the same result as going directly
to object code; the former would give long branches everywhere, whereas
the latter would use short branches where possible.
(2) Other useful branches, like COMPARE AND BRANCH, do not have long forms.
We would need to do something else before supporting them.
(Although COMPARE AND BRANCH does not change the condition codes,
the plan is to model COMPARE AND BRANCH as a CC-clobbering instruction
during codegen, so that we can safely lower it to a separate compare
and long branch where necessary. This is not a valid transformation
for the assembler proper to make.)
This patch therefore moves branch relaxation to a pre-emit pass.
For now, calls are still shortened from BRASL to BRAS by the assembler,
although this too is not really the traditional behaviour.
The first test takes about 1.5s to run, and there are likely to be
more tests in this vein once further branch types are added. The feeling
on IRC was that 1.5s is a bit much for a single test, so I've restricted
it to SystemZ hosts for now.
The patch exposes (and fixes) some typos in the main CodeGen/SystemZ tests.
A later patch will remove the {{g}}s from that directory.
llvm-svn: 182274
This adds the actual lib/Target/SystemZ target files necessary to
implement the SystemZ target. Note that at this point, the target
cannot yet be built since the configure bits are missing. Those
will be provided shortly by a follow-on patch.
This version of the patch incorporates feedback from reviews by
Chris Lattner and Anton Korobeynikov. Thanks to all reviewers!
Patch by Richard Sandiford.
llvm-svn: 181203
Jim Grosbach