The assembler currently strictly verifies that immediates for
s16imm operands are in range (-32768 ... 32767). This matches
the behaviour of the GNU assembler, with one exception: gas
allows, as a special case, operands in an extended range
(-65536 .. 65535) for the addis instruction only (and its
extended mnemonic lis).
The main reason for this seems to be to allow using unsigned
16-bit operands for lis, e.g. like lis %r1, 0xfedc.
Since this has been supported by gas for a long time, and
assembler source code seen "in the wild" actually exploits
this feature, this patch adds equivalent support to LLVM
for compatibility reasons.
llvm-svn: 184946
Currently, all instructions taking s16imm operands support symbolic
operands. However, for u16imm operands, we only support actual
immediate integers. This causes the assembler to reject code like
ori %r5, %r5, symbol@l
This patch changes the u16imm operand definition to likewise
accept symbolic operands. In fact, s16imm and u16imm can
share the same encoding routine, now renamed to getImm16Encoding.
llvm-svn: 184944
This adds pattern for the rldcr and rldic instructions (the last instruction
from the rotate/shift family that were missing). They are currently used
only by the asm parser.
llvm-svn: 184833
This adds support for the predicted forms of branches (+/-).
There are three cases to consider:
- Branches using a PPC::Predicate code
For these, I've added new PPC::Predicate codes corresponding
to the BO values for predicted branch forms, and updated insn
printing to print them correctly. I've also added new aliases
for the asm parser matching the new forms.
- bt/bf
I've added new aliases matching to gBC etc.
- bd(n)z variants
I've added new instruction patterns for the predicted forms.
In all cases, the new patterns are used for the asm parser only.
(The new infrastructure ought to be sufficient to allow use by
the compiler too at some point.)
llvm-svn: 184754
This adds instruction patterns to cover the generic forms of
the conditional branch instructions. This allows the assembler
to support the generic mnemonics.
The compiler will still generate the various specific forms
of the instruction that were already supported.
llvm-svn: 184722
There is currently only limited support for the "absolute" variants
of branch instructions. This patch adds support for the absolute
variants of all branches that are currently otherwise supported.
This requires adding new fixup types so that the correct variant
of relocation type can be selected by the object writer.
While the compiler will continue to usually choose the relative
branch variants, this will allow the asm parser to fully support
the absolute branches, with either immediate (numerical) or
symbolic target addresses.
No change in code generation intended.
llvm-svn: 184721
The GNU assembler supports (as extension to the ABI) use of PC-relative
relocations in half16 fields, which allows writing code like:
li 1, base-.
This patch adds support for those relocation types in the assembler.
llvm-svn: 184552
The current code base only supports the minimum set of tls-related
relocations and @modifiers that are necessary to support compiler-
generated code. This patch extends this to the full set defined
in the ABI (and supported by the GNU assembler) for the benefit
of the assembler parser.
llvm-svn: 184551
This adds necessary infrastructure to support the @h modifier.
Note that all required relocation types were already present
(and unused).
This patch provides support for using @h in the assembler;
it would also be possible to now use this feature in code
generated by the compiler, but this is not done yet.
llvm-svn: 184548
This renames more VK_PPC_ enums, to make them more closely reflect
the @modifier string they represent. This also prepares for adding
a bunch of new VK_PPC_ enums in upcoming patches.
For consistency, some MO_ flags related to VK_PPC_ enums are
likewise renamed.
No change in behaviour.
llvm-svn: 184547
This is another minor cleanup; to bring enum names in line
with the corresponding @modifier names, this renames:
VK_PPC_TOC -> VK_PPC_TOCBASE
VK_PPC_TOC_ENTRY -> VK_PPC_TOC16
No code change intended.
llvm-svn: 184491
This just re-sorts the big switch statement in
PPCELFObjectWriter::getRelocTypeInner to follow
the (numerical) order of the reloc types, and
fixes a couple of whitespace issues.
llvm-svn: 184485
This patch adds support for having the assembler optimize fixups
to constructs like "symbol@ha" or "symbol@l" if "symbol" can be
resolved at assembler time.
This optimization is already present in the PPCMCExpr.cpp code
for handling PPC_HA16/PPC_LO16 target expressions. However,
those target expression were used only on Darwin targets.
This patch changes target expression code so that they are
usable also with the GNU assembler (using the @ha / @l syntax
instead of the ha16() / lo16() syntax), and changes the
MCInst lowering code to generate those target expressions
where appropriate.
It also changes the asm parser to generate HA16/LO16 target
expressions when parsing assembler source that uses the
@ha / @l modifiers. The effect is that now the above-
mentioned optimization automatically becomes available
for those situations too.
llvm-svn: 184436
Frame index handling is now target-agnostic, so delete the target hooks
for creation & asm printing of target-specific addressing in DBG_VALUEs
and any related functions.
llvm-svn: 184067
I'm taking David Blaikie's suggestion to use an
Optional<PPC::Predicate> return value instead. That's the right
solution for this problem. Thanks for pointing out that possibility!
llvm-svn: 183858
This is a preparatory patch for fast-isel support. The instruction
selector will need to access some functions in PPCGenCallingConv.inc,
which in turn requires several helper functions to be defined. These
are currently defined near the only use of PCCGenCallingConv.inc,
inside PPCISelLowering.cpp. This patch moves the declaration of the
functions into the associated header file to provide the needed
visibility.
No functional change intended.
llvm-svn: 183844
Allows returning a PPC::Predicate from a function with a no-predicate
value possible. Preparatory patch for fast-isel on PPC64 ELF. No
behavioral change intended.
llvm-svn: 183841
I've been comparing the object file output of LLVM's integrated
assembler against the external assembler on PowerPC, and one
area where differences still remain are in DWARF sections.
In particular, the GNU assembler generates .debug_frame and
.debug_line sections using a code alignment factor of 4, since
all PowerPC instructions have size 4 and must be aligned to a
multiple of 4. However, current MC code hard-codes a code
alignment factor of 1.
This patch changes this by adding a "minimum instruction alignment"
data element to MCAsmInfo and using this as code alignment factor.
This requires passing a MCContext into MCDwarfLineAddr::Encode
and MCDwarfLineAddr::EncodeAdvanceLoc. Note that one caller,
MCDwarfLineAddr::Write, didn't actually have that information
available. However, it turns out that this routine is in fact
never used in the whole code base, so the patch simply removes
it. If it turns out to be needed again at a later time, it
could be re-added with an updated interface.
llvm-svn: 183834
A plain "sc" without argument is supposed to be treated like "sc 0"
by the assembler. This patch adds a corresponding alias.
Problem reported by Joerg Sonnenberger.
llvm-svn: 183687
The extended branch mnemonics are supposed to use an implied CR0
if there is no explicit condition register specified. This patch
adds extra variants of the mnemonics to this effect.
Problem reported by Joerg Sonnenberger.
llvm-svn: 183686
On PPC32, [su]div,rem on i64 types are transformed into runtime library
function calls. As a result, they are not allowed in counter-based loops (the
counter-loops verification pass caught this error; this change fixes PR16169).
llvm-svn: 183581
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
isConsecutiveLS is a slightly more general form of
SelectionDAG::isConsecutiveLoad. Aside from also handling stores, it also does
not assume equality of the chain operands is necessary. In the case of the PPC
backend, this chain condition is checked in a more general way by the
surrounding code.
Mostly, this part of the refactoring in preparation for supporting optimized
unaligned stores.
llvm-svn: 182723
When expanding unaligned Altivec loads, we use the decremented offset trick to
prevent page faults. Unfortunately, if we have a sequence of consecutive
unaligned loads, this leads to suboptimal code generation because the 'extra'
load from the first unaligned load can be combined with the base load from the
second (but only if the decremented offset trick is not used for the first).
Search up and down the chain, through loads and token factors, looking for
consecutive loads, and if one is found, don't use the offset reduction trick.
These duplicate loads are later combined to yield the desired sequence (in the
future, we might want a more-powerful chain search, but that will require some
changes to allow the combiner routines to access the AA object).
This should complete the initial implementation of the optimized unaligned
Altivec load expansion. There is some refactoring that should be done, but
that will happen when the unaligned store expansion is added.
llvm-svn: 182719
The lvsl permutation control instruction is a function only of the alignment of
the pointer operand (relative to the 16-byte natural alignment of Altivec
vectors). As a result, multiple lvsl intrinsics where the operands differ by a
multiple of 16 can be combined.
llvm-svn: 182708
Altivec only directly supports aligned loads, but the loads have a strange
property: If given an unaligned address, they truncate the address to the next
lower aligned address, and load from there. This property, along with an extra
load and some special-purpose permutation-control instructions that generate
the appropriate permutations from the original unaligned address, allow
efficient lowering of aligned loads. This code uses the trick explained in the
Apple Velocity Engine optimization overview document to prevent the needed
extra load from possibly causing a page fault if the original address happens
to be aligned.
As noted in the FIXMEs, there are several additional optimizations that can be
performed to reduce the cost of these loads even more. These will be
implemented in future commits.
llvm-svn: 182691
Now that there is no longer any distinction between symbolLo
and symbolHi operands in either printing, encoding, or parsing,
the operand types can be removed in favor of simply using
s16imm.
This completes the patch series to decouple lo/hi operand part
processing from the particular instruction whose operand it is.
No change in code generation expected from this patch.
llvm-svn: 182618
When targeting the Darwin assembler, we need to generate markers ha16() and
lo16() to designate the high and low parts of a (symbolic) immediate. This
is necessary not just for plain symbols, but also for certain symbolic
expression, typically along the lines of ha16(A - B). The latter doesn't
work when simply using VariantKind flags on the symbol reference.
This is why the current back-end uses hacks (explicitly called out as such
via multiple FIXMEs) in the symbolLo/symbolHi print methods.
This patch uses target-defined MCExpr codes to represent the Darwin
ha16/lo16 constructs, following along the lines of the equivalent solution
used by the ARM back end to handle their :upper16: / :lower16: markers.
This allows us to get rid of special handling both in the symbolLo/symbolHi
print method and in the common code MCExpr::print routine. Instead, the
ha16 / lo16 markers are printed simply in a custom print routine for the
target MCExpr types. (As a result, the symbolLo/symbolHi print methods
can now replaced by a single printS16ImmOperand routine that also handles
symbolic operands.)
The patch also provides a EvaluateAsRelocatableImpl routine to handle
ha16/lo16 constructs. This is not actually used at the moment by any
in-tree code, but is provided as it makes merging into David Fang's
out-of-tree Mach-O object writer simpler.
Since there is no longer any need to treat VK_PPC_GAS_HA16 and
VK_PPC_DARWIN_HA16 differently, they are merged into a single
VK_PPC_ADDR16_HA (and likewise for the _LO16 types).
llvm-svn: 182616
Using PatLeaf rather than ImmLeaf when defining immediate predicates
prevents simple patterns using those predicates from being recognized
for fast instruction selection. This patch replaces the immSExt16
PatLeaf predicate with two ImmLeaf predicates, imm32SExt16 and
imm64SExt16, allowing a few more patterns to be recognized (ADDI,
ADDIC, MULLI, ADDI8, and ADDIC8). Using the new predicates does not
help for LI, LI8, SUBFIC, and SUBFIC8 because these are rejected for
other reasons, but I see no reason to retain the PatLeaf predicate.
No functional change intended, and thus no test cases yet. This is
preliminary work for enabling fast-isel support for PowerPC. When
that support is ready, we'll be able to test this function.
llvm-svn: 182510
Although I had added some support for the BDZ/BDNZ branches into the selector
(in r158204), I had not correctly adjusted the condition at the top of the
loop. As a result, these branches were still essentially unsupported.
This fixes PR16086. Unfortunately, any test case would be very large (because
it would need to force the loop backedge to exceed the range of the 16-bit
immediate).
llvm-svn: 182385
Now that the preheader insertion logic in LoopSimplify is externally exposed,
use it, and remove the copy-and-pasted version.
No functionality change intended.
llvm-svn: 182300
As the pairing of this instruction form with the bdnz/bdz branches is now
enforced by the verification pass, make it clear from the name that these
are used only for counter-based loops.
No functionality change intended.
llvm-svn: 182296
When asserts are enabled, this adds a verification pass for PPC counter-loop
formation. Unfortunately, without sacrificing code quality, there is no better
way of forming counter-based loops except at the (late) IR level. This means
that we need to recognize, at the IR level, anything which might turn into a
function call (or indirect branch). Because this is currently a finite set of
things, and because SelectionDAG lowering is basic-block local, this can be
done. Nevertheless, it is fragile, and failure results in a miscompile. This
verification pass checks that all (reachable) counter-based branches are
dominated by a loop mtctr instruction, and that no instructions in between
clobber the counter register. If these conditions are not satisfied, then an
ICE will be triggered.
In short, this is to help us sleep better at night.
llvm-svn: 182295
We don't need to reject all inline asm as using the counter register (most does
not). Only those that explicitly clobber the counter register need to prevent
the transformation.
llvm-svn: 182191
This patch implements the equivalent change to r182091/r182092
in the old-style code emitter. Instead of having two separate
16-bit immediate encoding routines depending on the instruction,
this patch introduces a single encoder that checks the machine
operand flags to decide whether the low or high half of a
symbol address is required.
Since now both encoders make no further distinction between
"symbolLo" and "symbolHi", the .td operand can now use a
single getS16ImmEncoding method.
Tested by running the old-style JIT tests on 32-bit Linux.
llvm-svn: 182097
Now that fixup_ppc_ha16 and fixup_ppc_lo16 are being treated exactly
the same everywhere, it no longer makes sense to have two fixup types.
This patch merges them both into a single type fixup_ppc_half16,
and renames fixup_ppc_lo16_ds to fixup_ppc_half16ds for consistency.
(The half16 and half16ds names are taken from the description of
relocation types in the PowerPC ABI.)
No change in code generation expected.
llvm-svn: 182092
The current PowerPC MC back end distinguishes between fixup_ppc_ha16
and fixup_ppc_lo16, which are determined by the instruction the fixup
applies to, and uses this distinction to decide whether a fixup ought
to resolve to the high or the low part of a symbol address.
This isn't quite correct, however. It is valid -if unusual- assembler
to use, e.g.
li 1, symbol@ha
or
lis 1, symbol@l
Whether the high or the low part of the address is used depends solely
on the @ suffix, not on the instruction.
In addition, both
li 1, symbol
and
lis 1, symbol
are valid, assuming the symbol address fits into 16 bits; again, both
will then refer to the actual symbol value (so li will load the value
itself, while lis will load the value shifted by 16).
To fix this, two places need to be adapted. If the fixup cannot be
resolved at assembler time, a relocation needs to be emitted via
PPCELFObjectWriter::getRelocType. This routine already looks at
the VK_ type to determine the relocation. The only problem is that
will reject any _LO modifier in a ha16 fixup and vice versa. This
is simply incorrect; any of those modifiers ought to be accepted
for either fixup type.
If the fixup *can* be resolved at assembler time, adjustFixupValue
currently selects the high bits of the symbol value if the fixup
type is ha16. Again, this is incorrect; see the above example
lis 1, symbol
Now, in theory we'd have to respect a VK_ modifier here. However,
in fact common code never even attempts to resolve symbol references
using any nontrivial VK_ modifier at assembler time; it will always
fall back to emitting a reloc and letting the linker handle it.
If this ever changes, presumably there'd have to be a target callback
to resolve VK_ modifiers. We'd then have to handle @ha etc. there.
llvm-svn: 182091
Some IR-level instructions (such as FP <-> i64 conversions) are not chained
w.r.t. the mtctr intrinsic and yet may become function calls that clobber the
counter register. At the selection-DAG level, these might be reordered with the
mtctr intrinsic causing miscompiles. To avoid this situation, if an existing
preheader has instructions that might use the counter register, create a new
preheader for the mtctr intrinsic. This extra block will be remerged with the
old preheader at the MI level, but will prevent unwanted reordering at the
selection-DAG level.
llvm-svn: 182045
This is the second part of the change to always return "true"
offset values from getPreIndexedAddressParts, tackling the
case of "memrix" type operands.
This is about instructions like LD/STD that only have a 14-bit
field to encode immediate offsets, which are implicitly extended
by two zero bits by the machine, so that in effect we can access
16-bit offsets as long as they are a multiple of 4.
The PowerPC back end currently handles such instructions by
carrying the 14-bit value (as it will get encoded into the
actual machine instructions) in the machine operand fields
for such instructions. This means that those values are
in fact not the true offset, but rather the offset divided
by 4 (and then truncated to an unsigned 14-bit value).
Like in the case fixed in r182012, this makes common code
operations on such offset values not work as expected.
Furthermore, there doesn't really appear to be any strong
reason why we should encode machine operands this way.
This patch therefore changes the encoding of "memrix" type
machine operands to simply contain the "true" offset value
as a signed immediate value, while enforcing the rules that
it must fit in a 16-bit signed value and must also be a
multiple of 4.
This change must be made simultaneously in all places that
access machine operands of this type. However, just about
all those changes make the code simpler; in many cases we
can now just share the same code for memri and memrix
operands.
llvm-svn: 182032
DAGCombiner::CombineToPreIndexedLoadStore calls a target routine to
decompose a memory address into a base/offset pair. It expects the
offset (if constant) to be the true displacement value in order to
perform optional additional optimizations; in particular, to convert
other uses of the original pointer into uses of the new base pointer
after pre-increment.
The PowerPC implementation of getPreIndexedAddressParts, however,
simply calls SelectAddressRegImm, which returns a TargetConstant.
This value is appropriate for encoding into the instruction, but
it is not always usable as true displacement value:
- Its type is always MVT::i32, even on 64-bit, where addresses
ought to be i64 ... this causes the optimization to simply
always fail on 64-bit due to this line in DAGCombiner:
// FIXME: In some cases, we can be smarter about this.
if (Op1.getValueType() != Offset.getValueType()) {
- Its value is truncated to an unsigned 16-bit value if negative.
This causes the above opimization to generate wrong code.
This patch fixes both problems by simply returning the true
displacement value (in its original type). This doesn't
affect any other user of the displacement.
llvm-svn: 182012
The old PPCCTRLoops pass, like the Hexagon pass version from which it was
derived, could only handle some simple loops in canonical form. We cannot
directly adapt the new Hexagon hardware loops pass, however, because the
Hexagon pass contains a fundamental assumption that non-constant-trip-count
loops will contain a guard, and this is not always true (the result being that
incorrect negative counts can be generated). With this commit, we replace the
pass with a late IR-level pass which makes use of SE to calculate the
backedge-taken counts and safely generate the loop-count expressions (including
any necessary max() parts). This IR level pass inserts custom intrinsics that
are lowered into the desired decrement-and-branch instructions.
The most fragile part of this new implementation is that interfering uses of
the counter register must be detected on the IR level (and, on PPC, this also
includes any indirect branches in addition to function calls). Also, to make
all of this work, we need a variant of the mtctr instruction that is marked
as having side effects. Without this, machine-code level CSE, DCE, etc.
illegally transform the resulting code. Hopefully, this can be improved
in the future.
This new pass is smaller than the original (and much smaller than the new
Hexagon hardware loops pass), and can handle many additional cases correctly.
In addition, the preheader-creation code has been copied from LoopSimplify, and
after we decide on where it belongs, this code will be refactored so that it
can be explicitly shared (making this implementation even smaller).
The new test-case files ctrloop-{le,lt,ne}.ll have been adapted from tests for
the new Hexagon pass. There are a few classes of loops that this pass does not
transform (noted by FIXMEs in the files), but these deficiencies can be
addressed within the SE infrastructure (thus helping many other passes as well).
llvm-svn: 181927
We want the order to be deterministic on all platforms. NAKAMURA Takumi
fixed that in r181864. This patch is just two small cleanups:
* Move the function to the cpp file. It is only passed to array_pod_sort.
* Remove the ppc implementation which is now redundant
llvm-svn: 181910
Now that applyFixup understands differently-sized fixups, we can define
fixup_ppc_lo16/fixup_ppc_lo16_ds/fixup_ppc_ha16 to properly be 2-byte
fixups, applied at an offset of 2 relative to the start of the
instruction text.
This has the benefit that if we actually need to generate a real
relocation record, its address will come out correctly automatically,
without having to fiddle with the offset in adjustFixupOffset.
Tested on both 64-bit and 32-bit PowerPC, using external and
integrated assembler.
llvm-svn: 181894
The PPCAsmBackend::applyFixup routine handles the case where a
fixup can be resolved within the same object file. However,
this routine is currently hard-coded to assume the size of
any fixup is always exactly 4 bytes.
This is sort-of correct for fixups on instruction text; even
though it only works because several of what really would be
2-byte fixups are presented as 4-byte fixups instead (requiring
another hack in PPCELFObjectWriter::adjustFixupOffset to clean
it up).
However, this assumption breaks down completely for fixups
on data, which legitimately can be of any size (1, 2, 4, or 8).
This patch makes applyFixup aware of fixups of varying sizes,
introducing a new helper routine getFixupKindNumBytes (along
the lines of what the ARM back end does). Note that in order
to handle fixups of size 8, we also need to fix the return type
of adjustFixupValue to uint64_t to avoid truncation.
Tested on both 64-bit and 32-bit PowerPC, using external and
integrated assembler.
llvm-svn: 181891
The changes to CR spill handling missed a case for 32-bit PowerPC.
The code in PPCFrameLowering::processFunctionBeforeFrameFinalized()
checks whether CR spill has occurred using a flag in the function
info. This flag is only set by storeRegToStackSlot and
loadRegFromStackSlot. spillCalleeSavedRegisters does not call
storeRegToStackSlot, but instead produces MI directly. Thus we don't
see the CR is spilled when assigning frame offsets, and the CR spill
ends up colliding with some other location (generally the FP slot).
This patch sets the flag in spillCalleeSavedRegisters for PPC32 so
that the CR spill is properly detected and gets its own slot in the
stack frame.
llvm-svn: 181800
This fixes warning messages observed in the oggenc application test in
projects/test-suite. Special handling is needed for the 64-bit
PowerPC SVR4 ABI when a constant is initialized with a pointer to a
function in a shared library. Because a function address is
implemented as the address of a function descriptor, the use of copy
relocations can lead to problems with initialization. GNU ld
therefore replaces copy relocations with dynamic relocations to be
resolved by the dynamic linker. This means the constant cannot reside
in the read-only data section, but instead belongs in .data.rel.ro,
which is designed for constants containing dynamic relocations.
The implementation creates a class PPC64LinuxTargetObjectFile
inheriting from TargetLoweringObjectFileELF, which behaves like its
parent except to place constants of this sort into .data.rel.ro.
The test case is reduced from the oggenc application.
llvm-svn: 181723
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
The patch I committed as revision 167864 introduced a regression that
causes LLVM to no longer generate appropriate relocs for @ha/@l symbol
references (but fail an assertion instead).
This is fixed here by re-enabling support for the VK_PPC_GAS_HA16/
VK_PPC_GAS_LO16 variant kinds (and their Darwin variants) in
PPCELFObjectWriter.cpp.
Tested by running projects/test-suite in -m32 mode with the integrated
assembler forced on. A standalone test case will be committed shortly
as well.
llvm-svn: 181450
The floating-point record forms on PPC don't set the condition register bits
based on a comparison with zero (like the integer record forms do), but rather
based on the exception status bits.
llvm-svn: 181423
As pointed out by Evgeniy Stepanov, assigning a std::string temporary
to a StringRef is not a good idea. Rework MatchRegisterName to avoid
using the .lower routine.
llvm-svn: 181192
PowerPC assemblers are supposed to support a stand-alone '$' symbol
as an alternative of '.' to refer to the current PC. This does not
work in the LLVM assembler parser yet.
To avoid bootstrap failures when using the LLVM assembler as system
assembler, this patch modifies the assembler source code generated
by LLVM to avoid using '$' (and simply use '.' instead).
llvm-svn: 181054
This patch adds a couple of Book II instructions (isync, icbi) to the
PowerPC assembler parser. These are needed when bootstrapping clang
with the integrated assembler forced on, because they are used in
inline asm statements in the code base.
The test case adds the full list of Book II storage control instructions,
including associated extended mnemonics. Again, those that are not yet
supported as marked as FIXME.
llvm-svn: 181052
This patch adds infrastructure to support extended mnemonics in the
PowerPC assembler parser. It adds support specifically for those
extended mnemonics that LLVM will itself generate.
The test case lists *all* extended mnemonics according to the
PowerPC ISA v2.06 Book I, but marks those not yet supported
as FIXME.
llvm-svn: 181051
This adds assembler parser support to the PowerPC back end.
The parser will run for any powerpc-*-* and powerpc64-*-* triples,
but was tested only on 64-bit Linux. The supported syntax is
intended to be compatible with the GNU assembler.
The parser does not yet support all PowerPC instructions, but
it does support anything that is generated by LLVM itself.
There is no support for testing restricted instruction sets yet,
i.e. the parser will always accept any instructions it knows,
no matter what feature flags are given.
Instruction operands will be checked for validity and errors
generated. (Error handling in general could still be improved.)
The patch adds a number of test cases to verify instruction
and operand encodings. The tests currently cover all instructions
from the following PowerPC ISA v2.06 Book I facilities:
Branch, Fixed-point, Floating-Point, and Vector.
Note that a number of these instructions are not yet supported
by the back end; they are marked with FIXME.
A number of follow-on check-ins will add extra features. When
they are all included, LLVM passes all tests (including bootstrap)
when using clang -cc1as as the system assembler.
llvm-svn: 181050
In the default PowerPC assembler syntax, registers are specified simply
by number, so they cannot be distinguished from immediate values (without
looking at the opcode). This means that the default operand matching logic
for the asm parser does not work, and we need to specify custom matchers.
Since those can only be specified with RegisterOperand classes and not
directly on the RegisterClass, all instructions patterns used by the asm
parser need to use a RegisterOperand (instead of a RegisterClass) for
all their register operands.
This patch adds one RegisterOperand for each RegisterClass, using the
same name as the class, just in lower case, and updates all instruction
patterns to use RegisterOperand instead of RegisterClass operands.
llvm-svn: 180611
When testing the asm parser, I noticed wrong encodings for the
above instructions (wrong sub-opcodes).
Tests will be added together with the asm parser.
llvm-svn: 180608
When testing the asm parser, I noticed wrong encodings for the
above instructions (wrong sub-opcodes). Note that apparently
the compiler currently never generates pre-inc instructions
for floating point types for some reason ...
Tests will be added together with the asm parser.
llvm-svn: 180607
When testing the asm parser, I noticed wrong encodings for the
above instructions (wrong operand name in rldimi, wrong form
and sub-opcode for rldcl).
Tests will be added together with the asm parser.
llvm-svn: 180606
When testing the asm parser, I ran into an error when using a conditional
branch to an external symbol (this doesn't occur in compiler-generated
code) due to missing support in PPCELFObjectWriter::getRelocTypeInner.
llvm-svn: 180605
This exposed an issue with PowerPC AltiVec where it appears it was setting the wrong vector boolean contents. The included change
fixes the PowerPC tests, and was OK'd by Hal.
llvm-svn: 180129
The getSwappedPredicate function can be used in other places (such as in
improvements to the PPCCTRLoops pass). Instead of trapping it as a static
function in PPCInstrInfo, move it into PPCPredicates with other
predicate-related things.
No functionality change intended.
llvm-svn: 179926
When matching a compare with a subtract where the arguments of the compare are
swapped w.r.t. the arguments of the subtract, we need to negate the predicates
(or CR bit indices) of the users. This, however, is not the same as inverting
the predicate (negating LT -> GT, but inverting LT -> GE, for example). The ARM
backend seems to do this correctly, but when I adapted the code for the PPC
backend, I introduced an error in this logic.
Comparison optimization is now enabled again by default.
llvm-svn: 179899
Many PPC instructions have a so-called 'record form' which stores to a specific
condition register the result of comparing the result of the instruction with
zero (always as a signed comparison). For integer operations on PPC64, this is
always a 64-bit comparison.
This implementation is derived from the implementation in the ARM backend;
there are some differences because PPC condition registers are allocatable
virtual registers (although the record forms always use a specific one), and we
look for a matching subtraction instruction after the compare (but before the
first use) in addition to before it.
llvm-svn: 179802
A couple of recently introduced conditional branch patterns
also need to be marked as isCodeGenOnly since they cannot
be handled by the asm parser.
No change in generated code.
llvm-svn: 179690
Now that the CR spilling issues have been resolved, we can remove the
unmodeled-side-effect attributes from the comparison instructions (and also
mark them as isCompare). By allowing these, by default, to have unmodeled side
effects, we were hiding problems with CR spilling; but everything seems much
happier now.
llvm-svn: 179502
This fixes an ABI bug for non-Darwin PPC64. For the callee-saved condition
registers, the spill location is specified relative to the stack pointer (SP +
8). However, this is not relative to the SP after the new stack frame is
established, but instead relative to the caller's stack pointer (it is stored
into the linkage area of the parent's stack frame).
So, like with the link register, we don't directly spill the CRs with other
callee-saved registers, but just mark them to be spilled during prologue
generation.
In practice, this reverts r179457 for PPC64 (but leaves it in place for PPC32).
llvm-svn: 179500
Leaving MFCR has having unmodeled side effects is not enough to prevent
unwanted instruction reordering post-RA. We could probably apply a stronger
barrier attribute, but there is a better way: Add all (not just the first) CR
to be spilled as live-in to the entry block, and add all CRs to the MFCR
instruction as implicitly killed.
Unfortunately, I don't have a small test case.
llvm-svn: 179465
For functions that need to spill CRs, and have dynamic stack allocations, the
value of the SP during the restore is not what it was during the save, and so
we need to use the FP in these cases (as for all of the other spills and
restores, but the CR restore has a special code path because its reserved slot,
like the link register, is specified directly relative to the adjusted SP).
llvm-svn: 179457
TableGen will not combine nested list 'let' bindings into a single list, and
instead uses only the inner scope. As a result, several instruction definitions
were missing implicit register defs that were in outer scopes. This de-nests
these scopes and makes all instructions have only one let binding which sets
implicit register definitions.
llvm-svn: 179392
This is prep. work for the implementation of optimizeCompare. Many PPC
instructions have 'record' forms (in almost all cases, this means that the RC
bit is set) that cause the result of the instruction to be compared with zero,
and the result of that comparison saved in a predefined condition register. In
order to add the record forms of the instructions without too much
copy-and-paste, the relevant functions have been refactored into multiclasses
which define both the record and normal forms.
Also, two TableGen-generated mapping functions have been added which allow
querying the instruction code for the record form given the normal form (and
vice versa).
No functionality change intended.
llvm-svn: 179356
Because of how predication in implemented on PPC (only for branches), I think
that this is the right thing to do. No functionality change intended.
llvm-svn: 179252
I've not seen this happen in practice, and probably can't until we start
allowing decrement-counter-based conditional branches to be double predicated,
but just in case, don't allow predication of a diamond in which both sides have
ctr-defining branches. Even though the branching behavior of these can be
predicated, the counter-decrementing behavior cannot be.
llvm-svn: 179199
This adds in-principle support for if-converting the bctr[l] instructions.
These instructions are used for indirect branching. It seems, however, that the
current if converter will never actually predicate these. To do so, it would
need the ability to hoist a few setup insts. out of the conditionally-executed
block. For example, code like this:
void foo(int a, int (*bar)()) { if (a != 0) bar(); }
becomes:
...
beq 0, .LBB0_2
std 2, 40(1)
mr 12, 4
ld 3, 0(4)
ld 11, 16(4)
ld 2, 8(4)
mtctr 3
bctrl
ld 2, 40(1)
.LBB0_2:
...
and it would be safe to do all of this unconditionally with a predicated
beqctrl instruction.
llvm-svn: 179156
This enables us to form predicated branches (which are the same conditional
branches we had before) and also a larger set of predicated returns (including
instructions like bdnzlr which is a conditional return and loop-counter
decrement all in one).
At the moment, if conversion does not capture all possible opportunities. A
simple example is provided in early-ret2.ll, where if conversion forms one
predicated return, and then the PPCEarlyReturn pass picks up the other one. So,
at least for now, we'll keep both mechanisms.
llvm-svn: 179134
Some general cleanup and only scan the end of a BB for branches (once we're
done with the terminators and debug values, then there should not be any other
branches). These address post-commit review suggestions by Bill Schmidt.
No functionality change intended.
llvm-svn: 179112
On PowerPC, non-vector loads and stores have r+i forms; however, in functions
with large stack frames these were not being used to access slots far from the
stack pointer because such slots were out of range for the signed 16-bit
immediate offset field. This increases register pressure because we need a
separate register for each offset (when the r+r form is used). By enabling
virtual base registers, we can deal with large stack frames without unduly
increasing register pressure.
llvm-svn: 179105
PowerPC has a conditional branch to the link register (return) instruction: BCLR.
This should be used any time when we'd otherwise have a conditional branch to a
return. This adds a small pass, PPCEarlyReturn, which runs just prior to the
branch selection pass (and, importantly, after block placement) to generate
these conditional returns when possible. It will also eliminate unconditional
branches to returns (these happen rarely; most of the time these have already
been tail duplicated by the time PPCEarlyReturn is invoked). This is a nice
optimization for small functions that do not maintain a stack frame.
llvm-svn: 179026
First, we should not cheat: fsel-based lowering of select_cc is a
finite-math-only optimization (the ISA manual, section F.3 of v2.06, makes
this clear, as does a note in our own README).
This also adds fsel-based lowering of EQ and NE condition codes. As it turned
out, fsel generation was covered by a grand total of zero regression test
cases. I've added some test cases to cover the existing behavior (which is now
finite-math only), as well as the new EQ cases.
llvm-svn: 179000
There are certain PPC instructions into which we can fold a zero immediate
operand. We can detect such cases by looking at the register class required
by the using operand (so long as it is not otherwise constrained).
llvm-svn: 178961
On cores for which we know the misprediction penalty, and we have
the isel instruction, we can profitably perform early if conversion.
This enables us to replace some small branch sequences with selects
and avoid the potential stalls from mispredicting the branches.
Enabling this feature required implementing canInsertSelect and
insertSelect in PPCInstrInfo; isel code in PPCISelLowering was
refactored to use these functions as well.
llvm-svn: 178926
The manual states that there is a minimum of 13 cycles from when the
mispredicted branch is issued to when the correct branch target is
issued.
llvm-svn: 178925
On certain architectures we can support efficient vectorized version of
instructions if the operand value is uniform (splat) or a constant scalar.
An example of this is a vector shift on x86.
We can efficiently support
for (i = 0 ; i < ; i += 4)
w[0:3] = v[0:3] << <2, 2, 2, 2>
but not
for (i = 0; i < ; i += 4)
w[0:3] = v[0:3] << x[0:3]
This patch adds a parameter to getArithmeticInstrCost to further qualify operand
values as uniform or uniform constant.
Targets can then choose to return a different cost for instructions with such
operand values.
A follow-up commit will test this feature on x86.
radar://13576547
llvm-svn: 178807
BCL is normally a conditional branch-and-link instruction, but has
an unconditional form (which is used in the SjLj code, for example).
To make clear that this BCL instruction definition is specifically
the special unconditional form (which does not meaningfully take
a condition-register input), rename it to BCLalways.
No functionality change intended.
llvm-svn: 178803
The DAGCombine logic that recognized a/sqrt(b) and transformed it into
a multiplication by the reciprocal sqrt did not handle cases where the
sqrt and the division were separated by an fpext or fptrunc.
llvm-svn: 178801
This patch follows up on work done by Bill Schmidt in r178277,
and replaces most of the remaining uses of VRRC in ISEL DAG patterns.
The resulting .inc files are identical except for comments, so
no change in code generation is expected.
llvm-svn: 178656
For this we need to use a libcall. Previously LLVM didn't implement
libcall support for frem, so I've added it in the usual
straightforward manner. A test case from the bug report is included.
llvm-svn: 178639
When unsafe FP math operations are enabled, we can use the fre[s] and
frsqrte[s] instructions, which generate reciprocal (sqrt) estimates, together
with some Newton iteration, in order to quickly generate floating-point
division and sqrt results. All of these instructions are separately optional,
and so each has its own feature flag (except for the Altivec instructions,
which are covered under the existing Altivec flag). Doing this is not only
faster than using the IEEE-compliant fdiv/fsqrt instructions, but allows these
computations to be pipelined with other computations in order to hide their
overall latency.
I've also added a couple of missing fnmsub patterns which turned out to be
missing (but are necessary for good code generation of the Newton iterations).
Altivec needs a similar fix, but that will probably be more complicated because
fneg is expanded for Altivec's v4f32.
llvm-svn: 178617
Ulrich Weigand