Function attributes are the future! So just query whether we want to realign the
stack directly from the function instead of through a random target options
structure.
llvm-svn: 187618
Support for dynamic stack alignments in the PPC backend has been unfinished, in
part because it depends on dynamic stack realignment (which I only just
recently implemented fully). Now we can also support dynamic allocas with
higher than the default target stack alignment (16 bytes).
In order to round-up the requested size to the maximum requested alignment, we
need an additional register to hold the rounded-up size. We're already using one
scavenged register to hold the previous stack-pointer value (which needs to be
stored with the signal-safe stdux update), and so when we have dynamic allocas
and a large alignment, we allocate two emergency spill slots for the scavenger.
llvm-svn: 186562
First, this changes the base-pointer implementation to remove an unnecessary
complication (and one that is incompatible with how builtin SjLj is
implemented): instead of using r31 as the base pointer when it is not needed as
a frame pointer, now the base pointer will always be r30 when needed.
Second, we introduce another pseudo register, BP, which is used just like the FP
pseudo register to refer to the base register before we know for certain what
register it will be.
Third, we now save BP into the jmp_buf, and restore r30 from that slot in
longjmp. If the function that called setjmp did not use a base pointer, then
r30 will be overwritten by the setjmp-calling-function's restore code. FP
restoration (which is restored into r31) works the same way.
llvm-svn: 186545
This builds on some frame-lowering code that has existed since 2005 (r24224)
but was disabled in 2008 (r48188) because it needed base pointer support to
function correctly. This implementation follows the strategy suggested by Dale
Johannesen in r48188 where the following comment was added:
This does not currently work, because the delta between old and new stack
pointers is added to offsets that reference incoming parameters after the
prolog is generated, and the code that does that doesn't handle a variable
delta. You don't want to do that anyway; a better approach is to reserve
another register that retains to the incoming stack pointer, and reference
parameters relative to that.
And now we do exactly that. If we don't need a frame pointer, then we use r31
as a base pointer. If we do need a frame pointer, then we use r30 as a base
pointer. The base pointer retains the value of the stack pointer before it was
decremented in the prologue. We then use the base pointer to resolve all
negative frame indicies. The basic scheme follows that for base pointers in the
X86 backend.
We use a base pointer when we need to dynamically realign the incoming stack
pointer. This currently applies only to static objects (dynamic allocas with
large alignments, and base-pointer support in SjLj lowering will come in future
commits).
llvm-svn: 186478
Just as with mfocrf, it is also preferable to use mtocrf instead of
mtcrf when only a single CR register is to be written.
Current code however always emits mtcrf. This probably does not matter
when using an external assembler, since the GNU assembler will in fact
automatically replace mtcrf with mtocrf when possible. It does create
inefficient code with the integrated assembler, however.
To fix this, this patch adds MTOCRF/MTOCRF8 instruction patterns and
uses those instead of MTCRF/MTCRF8 everything. Just as done in the
MFOCRF patch committed as 185556, these patterns will be converted
back to MTCRF if MTOCRF is not available on the machine.
As a side effect, this allows to modify the MTCRF pattern to accept
the full range of mask operands for the benefit of the asm parser.
llvm-svn: 185561
When accessing just a single CR register, it is always preferable to
use mfocrf instead of mfcr, if the former is available on the CPU.
Current code makes that distinction in many, but not all places
where a single CR register value is retrieved. One missing
location is PPCRegisterInfo::lowerCRSpilling.
To fix this and make this simpler in the future, this patch changes
the bulk of the back-end to always assume mfocrf is available and
simply generate it when needed.
On machines that actually do not support mfocrf, the instruction
is replaced by mfcr at the very end, in EmitInstruction.
This has the additional benefit that we no longer need the
MFCRpseud hack, since before EmitInstruction we always have
a MFOCRF instruction pattern, which already models data flow
as required.
The patch also adds the MFOCRF8 version of the instruction,
which was missing so far.
Except for the PPCRegisterInfo::lowerCRSpilling case, no change
in generated code intended.
llvm-svn: 185556
There are a couple of (small) related changes here:
1. The printed name of the VRSAVE register has been changed from VRsave to
vrsave in order to match the name accepted by GNU binutils.
2. Support for parsing vrsave has been added to the asm parser (it seems that
there was no test case specifically covering this code, so I've added one).
3. The list of Altivec registers, which was common to all calling conventions,
has been separated out. This allows us to define the base CSR lists, and then
lists for each ABI with Altivec included. This allows SjLj, for example, to
work correctly on non-Altivec targets without using unnatural definitions of
the NoRegs CSR list.
4. VRSAVE is now always reserved on non-Darwin targets and all Altivec
registers are reserved when Altivec is disabled.
With these changes, it is now possible to compile a function containing
__builtin_unwind_init() on Linux/PPC64 with debugging information. This did not
work previously because GNU binutils assumes that all .cfi_offset offsets will
be 8-byte aligned on PPC64 (and errors out if you provide a non-8-byte-aligned
offset). This is not true for the vrsave register, however, because this
register is used only on Darwin, GCC does not bother printing a .cfi_offset
entry for it (even though there is a slot in the stack frame for it as
specified by the ABI). This change allows us to do the same: we will also not
print .cfi_offset directives for vrsave.
llvm-svn: 185409
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
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
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
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
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
ImmToIdxMap should be a DenseMap (not a std::map) because there
is no ordering requirement. Also, we don't need a separate list
of instructions for noImmForm in eliminateFrameIndex, because this
list is essentially the complement of the keys in ImmToIdxMap.
No functionality change intended.
llvm-svn: 178450
This instruction is available on modern PPC64 CPUs, and is now used
to improve the SINT_TO_FP lowering (by eliminating the need for the
separate sign extension instruction and decreasing the amount of
needed stack space).
llvm-svn: 178446
The existing SINT_TO_FP code for i32 -> float/double conversion was disabled
because it relied on broken EXTSW_32/STD_32 instruction definitions. The
original intent had been to enable these 64-bit instructions to be used on CPUs
that support them even in 32-bit mode. Unfortunately, this form of lying to
the infrastructure was buggy (as explained in the FIXME comment) and had
therefore been disabled.
This re-enables this functionality, using regular DAG nodes, but only when
compiling in 64-bit mode. The old STD_32/EXTSW_32 definitions (which were dead)
are removed.
llvm-svn: 178438
There were a few places where kill flags were not being set correctly, and
where 32-bit instruction variants were being used with 64-bit registers. After
r178180, this code was being triggered causing llc to assert.
llvm-svn: 178220
As Bill Schmidt pointed out to me, only on Darwin do we need to spill/restore
VRSAVE in the SjLj code. For non-Darwin, don't spill/restore VRSAVE (and I've
added some asserts to make sure that we're not).
As it turns out, we're not currently handling the Darwin case correctly (I've
added a FIXME in the test case). I've tried adding various implied register
definitions/uses to force the spill without success, so I'll need to address
this later.
llvm-svn: 178096
As pointed out by Jakob, we don't need to maintain a separate
register-numbering table. Instead we should let TableGen generate the table for
us from the information (already present) in PPCRegisterInfo.td.
TRI->getEncodingValue is now used to access register-encoding values.
No functionality change intended.
llvm-svn: 178067
Now that the register scavenger can support multiple spill slots, and PEI can
use virtual-register-based scavenging for multiple simultaneous registers, we
can use a virtual register for the transfer register in the CR spilling code.
This should eliminate the last place (outside of the prologue/epilogue) where
we depend on the unconditional availability of the r0 register. We will soon be
able to allocate it (in a somewhat restricted sense) as a GPR.
llvm-svn: 178060
PPC's use of PEI's virtual-register-based scavenging functionality had
redefined the virtual registers (it was non-SSA). Now that PEI supports
dealing with instructions with multiple virtual registers, this can be
cleanup up to use multiple virtual registers and keep SSA form.
No functionality change intended.
llvm-svn: 178059
These spilling functions will eventually make use of the register scavenger,
however, they'll do so by taking advantage of PEI's virtual-register-based
delayed scavenging mechanism. As a result, these function parameters will not
be used, and can be removed.
No functionality change intended.
llvm-svn: 177827
As Jakob pointed out in his review of r177423, having a shared ZERO
register between the 32- and 64-bit register classes causes this
odd G8RC_NOX0_and_GPRC_NOR0 class to be created. As recommended,
this adds a ZERO8 register which differentiates the 32- and 64-bit
zeros.
No functionality change intended.
llvm-svn: 177683
This implements SJLJ lowering on PPC, making the Clang functions
__builtin_{setjmp/longjmp} functional on PPC platforms. The implementation
strategy is similar to that on X86, with the exception that a branch-and-link
variant is used to get the right jump address. Credit goes to Bill Schmidt for
suggesting the use of the unconditional bcl form (instead of the regular bl
instruction) to limit return-address-cache pollution.
Benchmarking the speed at -O3 of:
static jmp_buf env_sigill;
void foo() {
__builtin_longjmp(env_sigill,1);
}
main() {
...
for (int i = 0; i < c; ++i) {
if (__builtin_setjmp(env_sigill)) {
goto done;
} else {
foo();
}
done:;
}
...
}
vs. the same code using the libc setjmp/longjmp functions on a P7 shows that
this builtin implementation is ~4x faster with Altivec enabled and ~7.25x
faster with Altivec disabled. This comparison is somewhat unfair because the
libc version must also save/restore the VSX registers which we don't yet
support.
llvm-svn: 177666
Although there is only one Altivec VRSAVE register, it is a member of
a register class, and we need the ability to spill it. Because this
register is normally callee-preserved and handled by special code this
has never before been necessary. However, this capability will be required by
a forthcoming commit adding SjLj support.
llvm-svn: 177654
The old code used to lower FRAMEADDR tried to replicate the logic in the real
frame-lowering code that determines whether or not the frame pointer (r31) will
be used. When it seemed as through the frame pointer would not be used, the
stack pointer (r1) was used instead. Unfortunately, because the stack size is
not yet known, this does not work. Instead, this change introduces new
always-reserved pseudo-registers (FP and FP8) that are replaced during prologue
insertion with the real frame-pointer register (either r1 or r31).
It is important that this intrinsic always return a valid frame address because
it is used by Clang to store the frame address as part of code generation for
__builtin_setjmp.
llvm-svn: 177653
Currently the PPC r0 register is unconditionally reserved. There are two reasons
for this:
1. r0 is treated specially (as the constant 0) by certain instructions, and so
cannot be used with those instructions as a regular register.
2. r0 is used as a temporary register in the CR-register spilling process
(where, under some circumstances, we require two GPRs).
This change addresses the first reason by introducing a restricted register
class (without r0) for use by those instructions that treat r0 specially. These
register classes have a new pseudo-register, ZERO, which represents the r0-as-0
use. This has the side benefit of making the existing target code simpler (and
easier to understand), and will make it clear to the register allocator that
uses of r0 as 0 don't conflict will real uses of the r0 register.
Once the CR spilling code is improved, we'll be able to allocate r0.
Adding these extra register classes, for some reason unclear to me, causes
requests to the target to copy 32-bit registers to 64-bit registers. The
resulting code seems correct (and causes no test-suite failures), and the new
test case covers this new kind of asymmetric copy.
As r0 is still reserved, no functionality change intended.
llvm-svn: 177423
This change cleans up two issues with Altivec register spilling:
1. The spilling code was inefficient (using two instructions, and add and a
load, when just one would do)
2. The code assumed that r0 would always be available (true for now, but this
will change)
The new code handles VR spilling just like GPR spills but forced into r+r mode.
As a result, when any VR spills are present, we must now always allocate the
register-scavenger spill slot.
llvm-svn: 177231
As a follow-up to r158719, remove PPCRegisterInfo::avoidWriteAfterWrite.
Jakob pointed out in response to r158719 that this callback is currently unused
and so this has no effect (and the speedups that I thought that I had observed
as a result of implementing this function must have been noise).
llvm-svn: 177228
Make requiresFrameIndexScavenging return true, and create virtual registers in
the spilling code instead of using the register scavenger directly. This makes
the target-level code simpler, and importantly, delays the scavenging until
after callee-saved register processing (which will be important for later
changes).
Also cleans up trackLivenessAfterRegAlloc (makes it inline in the header with
the other related functions). This makes it clear that it always returns true.
No functionality change intended.
llvm-svn: 177107
Now that only the register-scavenger version of the CR spilling code remains,
we no longer need the Darwin R2 hack. Darwin can use R0 as a spare register in
any case where the System V ABI uses it (R0 is special architecturally, and so
is reserved under all common ABIs).
A few test cases needed to be updated to reflect the register-allocation changes.
llvm-svn: 176868
This removes the -disable-ppc[32|64]-regscavenger options; the code
that uses the register scavenger has been working well (and has been the default)
for some time, and we don't need options to enable the old (broken) CR spilling code.
llvm-svn: 176865
This removes a const_cast hack from PPCRegisterInfo::hasReservedSpillSlot().
The proper place to save the frame index for the CR spill slot is in the
PPCFunctionInfo object, not the PPCRegisterInfo object.
No new test cases, as this just reimplements existing function. Existing
tests such as test/CodeGen/PowerPC/crsave.ll are sufficient.
llvm-svn: 175998
to TargetFrameLowering, where it belongs. Incidentally, this allows us
to delete some duplicated (and slightly different!) code in TRI.
There are potentially other layering problems that can be cleaned up
as a result, or in a similar manner.
The refactoring was OK'd by Anton Korobeynikov on llvmdev.
Note: this touches the target interfaces, so out-of-tree targets may
be affected.
llvm-svn: 175788
into their new header subdirectory: include/llvm/IR. This matches the
directory structure of lib, and begins to correct a long standing point
of file layout clutter in LLVM.
There are still more header files to move here, but I wanted to handle
them in separate commits to make tracking what files make sense at each
layer easier.
The only really questionable files here are the target intrinsic
tablegen files. But that's a battle I'd rather not fight today.
I've updated both CMake and Makefile build systems (I think, and my
tests think, but I may have missed something).
I've also re-sorted the includes throughout the project. I'll be
committing updates to Clang, DragonEgg, and Polly momentarily.
llvm-svn: 171366
directly.
This is in preparation for removing the use of the 'Attribute' class as a
collection of attributes. That will shift to the AttributeSet class instead.
llvm-svn: 171253
Sooooo many of these had incorrect or strange main module includes.
I have manually inspected all of these, and fixed the main module
include to be the nearest plausible thing I could find. If you own or
care about any of these source files, I encourage you to take some time
and check that these edits were sensible. I can't have broken anything
(I strictly added headers, and reordered them, never removed), but they
may not be the headers you'd really like to identify as containing the
API being implemented.
Many forward declarations and missing includes were added to a header
files to allow them to parse cleanly when included first. The main
module rule does in fact have its merits. =]
llvm-svn: 169131
r165941: Resubmit the changes to llvm core to update the functions to
support different pointer sizes on a per address space basis.
Despite this commit log, this change primarily changed stuff outside of
VMCore, and those changes do not carry any tests for correctness (or
even plausibility), and we have consistently found questionable or flat
out incorrect cases in these changes. Most of them are probably correct,
but we need to devise a system that makes it more clear when we have
handled the address space concerns correctly, and ideally each pass that
gets updated would receive an accompanying test case that exercises that
pass specificaly w.r.t. alternate address spaces.
However, from this commit, I have retained the new C API entry points.
Those were an orthogonal change that probably should have been split
apart, but they seem entirely good.
In several places the changes were very obvious cleanups with no actual
multiple address space code added; these I have not reverted when
I spotted them.
In a few other places there were merge conflicts due to a cleaner
solution being implemented later, often not using address spaces at all.
In those cases, I've preserved the new code which isn't address space
dependent.
This is part of my ongoing effort to clean out the partial address space
code which carries high risk and low test coverage, and not likely to be
finished before the 3.2 release looms closer. Duncan and I would both
like to see the above issues addressed before we return to these
changes.
llvm-svn: 167222
We use the enums to query whether an Attributes object has that attribute. The
opaque layer is responsible for knowing where that specific attribute is stored.
llvm-svn: 165488
