SystemZ wants normal register scavenging slots, as close to the stack or
frame pointer as possible. The only reason it was using custom code was
because PrologEpilogInserter assumed an x86-like layout, where the frame
pointer is at the opposite end of the frame from the stack pointer.
This meant that when frame pointer elimination was disabled,
the slots ended up being as close as possible to the incoming
stack pointer, which is the opposite of what we want on SystemZ.
This patch adds a new knob to say which layout is used and converts
SystemZ to use target-independent scavenging slots. It's one of the pieces
needed to support frame-to-frame MVCs, where two slots might be required.
The ABI requires us to allocate 160 bytes for calls, so one approach
would be to use that area as temporary spill space instead. It would need
some surgery to make sure that the slot isn't live across a call though.
I stuck to the "isFPCloseToIncomingSP - ..." style comment on the
"do what the surrounding code does" principle. The FP case is already
covered by several Systemz/frame-* tests, which fail without the
PrologueEpilogueInserter change, so no new ones are needed.
No behavioural change intended.
llvm-svn: 185696
Add a mapping from register-based <INSN>R instructions to the corresponding
memory-based <INSN>. Use it to cut down on the number of spill loads.
Some instructions extend their operands from smaller fields, so this
required a new TSFlags field to say how big the unextended operand is.
This optimisation doesn't trigger for C(G)R and CL(G)R because in practice
we always combine those instructions with a branch. Adding a test for every
other case probably seems excessive, but it did catch a missed optimisation
for DSGF (fixed in r185435).
llvm-svn: 185529
Rename Function->DispKey and PairType->DispSize. I'd originally used
"Function" because I thought it might be useful for other InstMappings.
However, it turns out that having two very similar instructions with the
same Function makes it pretty useless for anything other than the displacement
size key. Other InstMappings will want the key to be defined for only one
instruction in the pair.
No behavioural change intended.
llvm-svn: 185526
This is dead code since PIC16 was removed in 2010. The result was an odd mix,
where some parts would carefully pass it along and others would assert it was
zero (most of the object streamer for example).
llvm-svn: 185436
Fixes some cases where we were using full 64-bit division for (sdiv i32, i32)
and (sdiv i64, i32).
The "32" in "SDIVREM32" just refers to the second operand. The first operand
of all *DIVREM*s is a GR128.
llvm-svn: 185435
Try to use MVC when spilling the destination of a simple load or the source
of a simple store. As explained in the comment, this doesn't yet handle
the case where the load or store location is also a frame index, since
that could lead to two simultaneous scavenger spills, something the
backend can't handle yet. spill-02.py tests that this restriction kicks in,
but unfortunately I've not yet found a case that would fail without it.
The volatile trick I used for other scavenger tests doesn't work here
because we can't use MVC for volatile accesses anyway.
I'm planning on relaxing the restriction later, hopefully with a test
that does trigger the problem...
Tests @f8 and @f9 also showed that L(G)RL and ST(G)RL were wrongly
classified as SimpleBDX{Load,Store}. It wouldn't be easy to test for
that bug separately, which is why I didn't split out the fix as a
separate patch.
llvm-svn: 185434
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
Add pseudo conditional store instructions, so that we use:
branch foo:
store
foo:
instead of:
load
branch foo:
move
foo:
store
z196 has real 32-bit and 64-bit conditional stores, but we don't use
any z196 instructions yet.
llvm-svn: 185065
NOTE: If this broke your out-of-tree backend, in *RegisterInfo.td, change
the instances of SubRegIndex that have a comps template arg to use the
ComposedSubRegIndex class instead.
In TableGen land, this adds Size and Offset attributes to SubRegIndex,
and the ComposedSubRegIndex class, for which the Size and Offset are
computed by TableGen. This also adds an accessor in MCRegisterInfo, and
Size/Offsets for the X86 and ARM subreg indices.
llvm-svn: 183020
Unlike most -- hopefully "all other", but I'm still checking -- memory
instructions we support, LOAD REVERSED and STORE REVERSED may access
the memory location several times. This means that they are not suitable
for volatile loads and stores.
This patch is a prerequisite for better atomic load and store support.
The same principle applies there: almost all memory instructions we
support are inherently atomic ("block concurrent"), but LOAD REVERSED
and STORE REVERSED are exceptions.
Other instructions continue to allow volatile operands. I will add
positive "allows volatile" tests at the same time as the "allows atomic
load or store" tests.
llvm-svn: 183002
The code to distinguish between unaligned and aligned addresses was
already there, so this is mostly just a switch-on-and-test process.
llvm-svn: 182920
Fixes PR16146: gdb.base__call-ar-st.exp fails after
pre-RA-sched=source fixes.
Patch by Xiaoyi Guo!
This also fixes an unsupported dbg.value test case. Codegen was
previously incorrect but the test was passing by luck.
llvm-svn: 182885
This patch adds support for the CRJ and CGRJ instructions. Support for
the immediate forms will be a separate patch.
The architecture has a large number of comparison instructions. I think
it's generally better to concentrate on using the "best" comparison
instruction first and foremost, then only use something like CRJ if
CR really was the natual choice of comparison instruction. The patch
therefore opportunistically converts separate CR and BRC instructions
into a single CRJ while emitting instructions in ISelLowering.
llvm-svn: 182764
Previously, an invalid instruction like:
foo %r1, %r0
would generate the rather odd error message:
....: error: unknown token in expression
foo %r1, %r0
^
We now get the more informative:
....: error: invalid instruction
foo %r1, %r0
^
The same would happen if an address were used where a register was expected.
We now get "invalid operand for instruction" instead.
llvm-svn: 182644
The idea is to make sure that:
(1) "register expected" is restricted to cases where ParseRegister()
is called and the token obviously isn't a register.
(2) "invalid register" is restricted to cases where a register-like "%..."
sequence is found, but the "..." makes no sense.
(3) the generic "invalid operand for instruction" is used in cases where
the wrong register type is used (GPR instead of FPR, etc.).
(4) the new "invalid register pair" is used if the register has the right type,
but is not a valid register pair.
Testing of (1)-(3) is now restricted to regs-bad.s. It uses a representative
instruction for each register class to make sure that only registers from
that class are accepted.
(4) is tested by both regs-bad.s (which checks all invalid register pairs)
and insn-bad.s (which tests one invalid pair for each instruction that
requires a pair).
While there, I changed "Number" to "Num" for consistency with the
operand class.
llvm-svn: 182643
There was exactly one caller using this API right, the others were relying on
specific behavior of the default implementation. Since it's too hard to use it
right just remove it and standardize on the default behavior.
Defines away PR16132.
llvm-svn: 182636
Addresses a review comment from Ulrich Weigand. No functional change intended.
I'm not sure whether the old TODO that this patch touches still holds,
but that's something we'd get to when adding a targetted scheduling
description.
llvm-svn: 182474
The original version of the pass could underestimate the length of a backward
branch in cases like:
alignment to N bytes or more
...
relaxable branch A
...
foo: (aligned to M<N bytes)
...
bar: (aligned to N bytes)
...
relaxable branch B to foo
We don't add any misalignment gap for "bar" because N bytes of alignment
had already been reached earlier in the function. In this case, assuming
that A is relaxed can push "foo" closer to "bar", and make B appear to be
in range. Similar problems can occur for forward branches.
I don't think it's possible to create blocks with mixed alignments as
things stand, not least because we haven't yet defined getPrefLoopAlignment()
for SystemZ (that would need benchmarking). So I don't think we can test
this yet.
Thanks to Rafael Espíndola for spotting the bug.
llvm-svn: 182460
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
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
Marking instructions as isAsmParserOnly stops them from being disassembled.
However, in cases where separate asm and codegen versions exist, we actually
want to disassemble to the asm ones.
No functional change intended.
llvm-svn: 181772
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: 181771
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
It was just a less powerful and more confusing version of
MCCFIInstruction. A side effect is that, since MCCFIInstruction uses
dwarf register numbers, calls to getDwarfRegNum are pushed out, which
should allow further simplifications.
I left the MachineModuleInfo::addFrameMove interface unchanged since
this patch was already fairly big.
llvm-svn: 181680
Richard Sandiford