The backend previously folded offsets into PC-relative addresses
whereever possible. That's the right thing to do when the address
can be used directly in a PC-relative memory reference (using things
like LRL). But if we have a register-based memory reference and need
to load the PC-relative address separately, it's better to use an anchor
point that could be shared with other accesses to the same area of the
variable.
Fixes a FIXME.
llvm-svn: 191524
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
For some reason I never got around to adding these at the same time as
the signed versions. No idea why.
I'm not sure whether this SystemZII::BranchC* stuff is useful, or whether
it should just be replaced with an "is normal" flag. I'll leave that
for later though.
There are some boundary conditions that can be tweaked, such as preferring
unsigned comparisons for equality with [128, 256), and "<= 255" over "< 256",
but again I'll leave those for a separate patch.
llvm-svn: 190930
Lengths up to a certain threshold (currently 6 * 256) use a series of MVCs.
Lengths above that threshold use a loop to handle X*256 bytes followed
by a single MVC to handle the excess (if any). This loop will also be
needed in future when support for variable lengths is added.
Because the same tablegen classes are used to define MVC and CLC,
the patch also has the side-effect of defining a pseudo loop instruction
for CLC. That instruction isn't used yet (and wouldn't be handled correctly
if it were). I'm planning to use it soon though.
llvm-svn: 189331
If we had a store of an integer to memory, and the integer and store size
were suitable for a form of MV..., we used MV... no matter what. We could
then have sequences like:
lay %r2, 0(%r3,%r4)
mvi 0(%r2), 4
In these cases it seems better to force the constant into a register
and use a normal store:
lhi %r2, 4
stc %r2, 0(%r3, %r4)
since %r2 is more likely to be hoisted and is easier to rematerialize.
llvm-svn: 189098
Extend r187495 to conditional loads. I split this out because the
easiest way seemed to be to force a particular operand order in
SystemZISelDAGToDAG.cpp.
llvm-svn: 187496
This is the first use of D(L,B) addressing, which required a fair bit
of surgery. For that reason, the patch just adds the instruction
definition and the associated assembler and disassembler support.
A later patch will actually make use of it for codegen.
llvm-svn: 185433
The GNU assembler treats things like:
brasl %r14, 100
in the same way as:
brasl %r14, .+100
rather than as a branch to absolute address 100. We implemented this in
LLVM by creating an immediate operand rather than the usual expr operand,
and by handling immediate operands specially in the code emitter.
This was undesirable for (at least) three reasons:
- the specialness of immediate operands was exposed to the backend MC code,
rather than being limited to the assembler parser.
- in disassembly, an immediate operand really is an absolute address.
(Note that this means reassembling printed disassembly can't recreate
the original code.)
- it would interfere with any assembly manipulation that we might
try in future. E.g. operations like branch shortening can change
the relative position of instructions, but any code that updates
sym+offset addresses wouldn't update an immediate "100" operand
in the same way as an explicit ".+100" operand.
This patch changes the implementation so that the assembler creates
a "." label for immediate PC-relative operands, so that the operand
to the MCInst is always the absolute address. The patch also adds
some error checking of the offset.
llvm-svn: 181773
The SystemZ port currently relies on the order of the instruction operands
matching the order of the instruction field lists. This isn't desirable
for disassembly, where the two are matched only by name. E.g. the R1 and R2
fields of an RR instruction should have corresponding R1 and R2 operands.
The main complication is that addresses are compound operands,
and as far as I know there is no mechanism to allow individual
suboperands to be selected by name in "let Inst{...} = ..." assignments.
Luckily it doesn't really matter though. The SystemZ instruction
encoding groups all address fields together in a predictable order,
so it's just as valid to see the entire compound address operand as
a single field. That's the approach taken in this patch.
Matching by name in turn means that the operands to COPY SIGN and
CONVERT TO FIXED instructions can be given in natural order.
(It was easier to do this at the same time as the rename,
since otherwise the intermediate step was too confusing.)
No functional change intended.
llvm-svn: 181769
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
Richard Sandiford