This changes the interface of how targets describe how to legalize, see
the below description.
1. Interface for targets to describe how to legalize.
In GlobalISel, the API in the LegalizerInfo class is the main interface
for targets to specify which types are legal for which operations, and
what to do to turn illegal type/operation combinations into legal ones.
For each operation the type sizes that can be legalized without having
to change the size of the type are specified with a call to setAction.
This isn't different to how GlobalISel worked before. For example, for a
target that supports 32 and 64 bit adds natively:
for (auto Ty : {s32, s64})
setAction({G_ADD, 0, s32}, Legal);
or for a target that needs a library call for a 32 bit division:
setAction({G_SDIV, s32}, Libcall);
The main conceptual change to the LegalizerInfo API, is in specifying
how to legalize the type sizes for which a change of size is needed. For
example, in the above example, how to specify how all types from i1 to
i8388607 (apart from s32 and s64 which are legal) need to be legalized
and expressed in terms of operations on the available legal sizes
(again, i32 and i64 in this case). Before, the implementation only
allowed specifying power-of-2-sized types (e.g. setAction({G_ADD, 0,
s128}, NarrowScalar). A worse limitation was that if you'd wanted to
specify how to legalize all the sized types as allowed by the LLVM-IR
LangRef, i1 to i8388607, you'd have to call setAction 8388607-3 times
and probably would need a lot of memory to store all of these
specifications.
Instead, the legalization actions that need to change the size of the
type are specified now using a "SizeChangeStrategy". For example:
setLegalizeScalarToDifferentSizeStrategy(
G_ADD, 0, widenToLargerAndNarrowToLargest);
This example indicates that for type sizes for which there is a larger
size that can be legalized towards, do it by Widening the size.
For example, G_ADD on s17 will be legalized by first doing WidenScalar
to make it s32, after which it's legal.
The "NarrowToLargest" indicates what to do if there is no larger size
that can be legalized towards. E.g. G_ADD on s92 will be legalized by
doing NarrowScalar to s64.
Another example, taken from the ARM backend is:
for (unsigned Op : {G_SDIV, G_UDIV}) {
setLegalizeScalarToDifferentSizeStrategy(Op, 0,
widenToLargerTypesUnsupportedOtherwise);
if (ST.hasDivideInARMMode())
setAction({Op, s32}, Legal);
else
setAction({Op, s32}, Libcall);
}
For this example, G_SDIV on s8, on a target without a divide
instruction, would be legalized by first doing action (WidenScalar,
s32), followed by (Libcall, s32).
The same principle is also followed for when the number of vector lanes
on vector data types need to be changed, e.g.:
setAction({G_ADD, LLT::vector(8, 8)}, LegalizerInfo::Legal);
setAction({G_ADD, LLT::vector(16, 8)}, LegalizerInfo::Legal);
setAction({G_ADD, LLT::vector(4, 16)}, LegalizerInfo::Legal);
setAction({G_ADD, LLT::vector(8, 16)}, LegalizerInfo::Legal);
setAction({G_ADD, LLT::vector(2, 32)}, LegalizerInfo::Legal);
setAction({G_ADD, LLT::vector(4, 32)}, LegalizerInfo::Legal);
setLegalizeVectorElementToDifferentSizeStrategy(
G_ADD, 0, widenToLargerTypesUnsupportedOtherwise);
As currently implemented here, vector types are legalized by first
making the vector element size legal, followed by then making the number
of lanes legal. The strategy to follow in the first step is set by a
call to setLegalizeVectorElementToDifferentSizeStrategy, see example
above. The strategy followed in the second step
"moreToWiderTypesAndLessToWidest" (see code for its definition),
indicating that vectors are widened to more elements so they map to
natively supported vector widths, or when there isn't a legal wider
vector, split the vector to map it to the widest vector supported.
Therefore, for the above specification, some example legalizations are:
* getAction({G_ADD, LLT::vector(3, 3)})
returns {WidenScalar, LLT::vector(3, 8)}
* getAction({G_ADD, LLT::vector(3, 8)})
then returns {MoreElements, LLT::vector(8, 8)}
* getAction({G_ADD, LLT::vector(20, 8)})
returns {FewerElements, LLT::vector(16, 8)}
2. Key implementation aspects.
How to legalize a specific (operation, type index, size) tuple is
represented by mapping intervals of integers representing a range of
size types to an action to take, e.g.:
setScalarAction({G_ADD, LLT:scalar(1)},
{{1, WidenScalar}, // bit sizes [ 1, 31[
{32, Legal}, // bit sizes [32, 33[
{33, WidenScalar}, // bit sizes [33, 64[
{64, Legal}, // bit sizes [64, 65[
{65, NarrowScalar} // bit sizes [65, +inf[
});
Please note that most of the code to do the actual lowering of
non-power-of-2 sized types is currently missing, this is just trying to
make it possible for targets to specify what is legal, and how non-legal
types should be legalized. Probably quite a bit of further work is
needed in the actual legalizing and the other passes in GlobalISel to
support non-power-of-2 sized types.
I hope the documentation in LegalizerInfo.h and the examples provided in the
various {Target}LegalizerInfo.cpp and LegalizerInfoTest.cpp explains well
enough how this is meant to be used.
This drops the need for LLT::{half,double}...Size().
Differential Revision: https://reviews.llvm.org/D30529
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@317560 91177308-0d34-0410-b5e6-96231b3b80d8
The new legalize combiner introduces shifts all over the place, so we
should support them sooner rather than later.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@315064 91177308-0d34-0410-b5e6-96231b3b80d8
With this change, the GlobalISel library gets always built. In
particular, this is not possible to opt GlobalISel out of the build
using the LLVM_BUILD_GLOBAL_ISEL variable any more.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@309990 91177308-0d34-0410-b5e6-96231b3b80d8
Insert a TSTri to set the flags and a Bcc to branch based on their
values. This is a bit inefficient in the (common) cases where the
condition for the branch comes from a compare right before the branch,
since we set the flags both as part of the compare lowering and as part
of the branch lowering. We're going to live with that until we settle on
a principled way to handle this kind of situation, which occurs with
other patterns as well (combines might be the way forward here).
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@308009 91177308-0d34-0410-b5e6-96231b3b80d8
We used to forget to erase the original instruction when replacing a
G_FCMP true/false. Fix this bug and make sure the tests check for it.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@307639 91177308-0d34-0410-b5e6-96231b3b80d8
This covers both hard and soft float.
Hard float is easy, since it's just Legal.
Soft float is more involved, because there are several different ways to
handle it based on the predicate: one and ueq need not only one, but two
libcalls to get a result. Furthermore, we have large differences between
the values returned by the AEABI and GNU functions.
AEABI functions return a nice 1 or 0 representing true and respectively
false. GNU functions generally return a value that needs to be compared
against 0 (e.g. for ogt, the value returned by the libcall is > 0 for
true). We could introduce redundant comparisons for AEABI as well, but
they don't seem easy to remove afterwards, so we do different processing
based on whether or not the result really needs to be compared against
something (and just truncate if it doesn't).
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@307243 91177308-0d34-0410-b5e6-96231b3b80d8
We used to have a helper that replaced an instruction with a libcall.
That turns out to be too aggressive, since sometimes we need to replace
the instruction with at least two libcalls. Therefore, change our
existing helper to only create the libcall and leave the instruction
removal as a separate step. Also rename the helper accordingly.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@307149 91177308-0d34-0410-b5e6-96231b3b80d8
In r301116, a custom lowering needed to be introduced to be able to
legalize 8 and 16-bit divisions on ARM targets without a division
instruction, since 2-step legalization (WidenScalar from 8 bit to 32
bit, then Libcall the 32-bit division) doesn't work.
This fixes this and makes this kind of multi-step legalization, where
first the size of the type needs to be changed and then some action is
needed that doesn't require changing the size of the type,
straighforward to specify.
Differential Revision: https://reviews.llvm.org/D32529
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@306806 91177308-0d34-0410-b5e6-96231b3b80d8
* Mark as legal for (s32, i1, s32, s32)
* Map everything into GPRs
* Select to two instructions: a CMP of the condition against 0, to set
the flags, and a MOVCCr to select between the two inputs based on the
flags that we've just set
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@306382 91177308-0d34-0410-b5e6-96231b3b80d8
Add support throughout the pipeline:
- mark as legal for s32 and pointers
- map to GPRs
- lower to a sequence of instructions, which moves 0 or 1 into the
result register based on the flags set by a CMPrr
We have copied from FastISel a helper function which maps CmpInst
predicates into ARMCC codes. Ideally, we should be able to move it
somewhere that both FastISel and GlobalISel can use.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@305672 91177308-0d34-0410-b5e6-96231b3b80d8
Add support for modulo for targets that have hardware division and for
those that don't. When hardware division is not available, we have to
choose the correct libcall to use. This is generally straightforward,
except for AEABI.
The AEABI variant is trickier than the other libcalls because it
returns { quotient, remainder }, instead of just one value like the
other libcalls that we've seen so far. Therefore, we need to use custom
lowering for it. However, we don't want to have too much special code,
so we refactor the target-independent code in the legalizer by adding a
helper for replacing an instruction with a libcall. This helper is used
by the legalizer itself when dealing with simple calls, and also by the
custom ARM legalization for the more complicated AEABI divmod calls.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@305459 91177308-0d34-0410-b5e6-96231b3b80d8
Same as the other binary operators:
- legalize to 32 bits
- map to GPRs
- select to EORrr via TableGen'erated code
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@304898 91177308-0d34-0410-b5e6-96231b3b80d8
Same as the other binary operators:
- legalize to 32 bits
- map to GPRs
- select ORRrr thanks to TableGen'erated code
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@304890 91177308-0d34-0410-b5e6-96231b3b80d8
This is identical to the support for the other binary operators:
- widen to s32
- map into GPR
- select ANDrr (via TableGen'erated code)
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@304885 91177308-0d34-0410-b5e6-96231b3b80d8
This is the same as r292827 for AArch64: we widen 8- and 16-bit ADD, SUB
and MUL to 32 bits since we only have TableGen patterns for 32 bits.
See the commit message for r292827 for more details.
At this point we could just remove some of the tests for regbankselect
and instruction-select, since we're not going to see any narrow
operations at those levels anymore. Instead I decided to update them
with G_ANYEXT/G_TRUNC operations, so we can validate the full sequences
generated by the legalizer.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@302782 91177308-0d34-0410-b5e6-96231b3b80d8
We have to widen the operands to 32 bits and then we can either use
hardware division if it is available or lower to a libcall otherwise.
At the moment it is not enough to set the Legalizer action to
WidenScalar, since for libcalls it won't know what to do (it won't be
able to find what size to widen to, because it will find Libcall and not
Legal for 32 bits). To hack around this limitation, we request Custom
lowering, and as part of that we widen first and then we run another
legalizeInstrStep on the widened DIV.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@301166 91177308-0d34-0410-b5e6-96231b3b80d8
Add support for both targets with hardware division and without. For
hardware division we have to add support throughout the pipeline
(legalizer, reg bank select, instruction select). For targets without
hardware division, we only need to mark it as a libcall.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@301164 91177308-0d34-0410-b5e6-96231b3b80d8
Support G_MUL, very similar to G_ADD and G_SUB. The only difference is
in the instruction selector, where we have to select either MUL or MULv5
depending on the target.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@300665 91177308-0d34-0410-b5e6-96231b3b80d8
Use the same handling in the generic legalizer code as for the other
libcalls (G_FREM, G_FPOW).
Enable it on ARM for float and double so we can test it.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@299931 91177308-0d34-0410-b5e6-96231b3b80d8
Legalize to a libcall.
On this occasion, also start allowing soft float subtargets. For the
moment G_FREM is the only legal floating point operation for them.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@299753 91177308-0d34-0410-b5e6-96231b3b80d8
At the moment we're only interested in GEPs for putting call parameters on the
stack, so we'll stick to 32-bit offsets.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@296452 91177308-0d34-0410-b5e6-96231b3b80d8
Start using the Subtarget to make decisions about what's legal. In particular,
we only mark floating point operations as legal if we have VFP2, which is
something we should've done from the very start.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@295439 91177308-0d34-0410-b5e6-96231b3b80d8
For now we just mark them as legal all the time and let the other passes bail
out if they can't handle it. In the future, we'll want to move more of the
brains into the legalizer.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@295300 91177308-0d34-0410-b5e6-96231b3b80d8
Add a register bank for floating point values and select simple instructions
using them (add, copies from GPR).
This assumes that the hardware can cope with a single precision add (VADDS)
instruction, so the legalizer will treat G_FADD as legal and the instruction
selector will refuse to select if the hardware doesn't support it. In the future
we'll want to be more careful about this, and legalize to libcalls if we have to
use soft float.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@294442 91177308-0d34-0410-b5e6-96231b3b80d8
Make it legal to load pointer values. Also check that pointers are assigned
to the GPR reg bank by default.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@293886 91177308-0d34-0410-b5e6-96231b3b80d8
This is to fix the win7 bot that does not seem to be very
good at infering the type when it gets used in an initiliazer list.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@293248 91177308-0d34-0410-b5e6-96231b3b80d8
Add support for loading i1, i8 and i16 arguments from the stack, with or without
the ABI extension flags.
When the ABI extension flags are present, we load a 4-byte value, otherwise we
preserve the size of the load and let the instruction selector replace it with a
LDRB/LDRH. This generates the same thing as DAGISel.
Differential Revision: https://reviews.llvm.org/D27803
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@293163 91177308-0d34-0410-b5e6-96231b3b80d8
At the moment, this means supporting the signext/zeroext attribute on the return
type of the function. For function arguments, signext/zeroext should be handled
by the caller, so there's nothing for us to do until we start lowering calls.
Note that this does not include support for other extensions (i8 to i16), those
will be added later.
Differential Revision: https://reviews.llvm.org/D27705
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@293034 91177308-0d34-0410-b5e6-96231b3b80d8
Add the minimal support necessary to select a function that returns the sum of
two i32 values.
This includes some support for argument/return lowering of i32 values through
registers, as well as the handling of copy and add instructions throughout the
GlobalISel pipeline.
Differential Revision: https://reviews.llvm.org/D26677
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@289940 91177308-0d34-0410-b5e6-96231b3b80d8
