The function TRI::getCommonSubClass(A, B) returns the largest common
sub-class of the register classes A and B. This patch teaches TableGen
to synthesize sub-classes such that the answer is always maximal.
In other words, every register that is in both A and B will also be
present in getCommonSubClass(A, B).
This introduces these synthetic register classes:
ARM:
GPRnopc_and_hGPR
GPRnopc_and_hGPR
hGPR_and_rGPR
GPRnopc_and_hGPR
GPRnopc_and_hGPR
hGPR_and_rGPR
tGPR_and_tcGPR
hGPR_and_tcGPR
X86:
GR32_NOAX_and_GR32_NOSP
GR32_NOAX_and_GR32_NOREX
GR64_NOSP_and_GR64_TC
GR64_NOSP_and_GR64_TC
GR64_NOREX_and_GR64_TC
GR32_NOAX_and_GR32_NOSP
GR32_NOAX_and_GR32_NOREX
GR32_NOAX_and_GR32_NOREX_NOSP
GR64_NOSP_and_GR64_TC
GR64_NOREX_and_GR64_TC
GR64_NOREX_NOSP_and_GR64_TC
GR32_NOAX_and_GR32_NOSP
GR32_NOAX_and_GR32_NOREX
GR32_NOAX_and_GR32_NOREX_NOSP
GR32_ABCD_and_GR32_NOAX
GR32_NOAX_and_GR32_NOSP
GR32_NOAX_and_GR32_NOREX
GR32_NOAX_and_GR32_NOREX_NOSP
GR32_ABCD_and_GR32_NOAX
GR32_NOAX_and_GR32_TC
GR32_NOAX_and_GR32_NOSP
GR64_NOSP_and_GR64_TC
GR32_NOAX_and_GR32_NOREX
GR32_NOAX_and_GR32_NOREX_NOSP
GR64_NOREX_and_GR64_TC
GR64_NOREX_NOSP_and_GR64_TC
GR32_ABCD_and_GR32_NOAX
GR64_ABCD_and_GR64_TC
GR32_NOAX_and_GR32_TC
GR32_AD_and_GR32_NOAX
Other targets are unaffected.
llvm-svn: 146657
This function is used to constrain a register class to a sub-class that
supports the given sub-register index.
For example, getSubClassWithSubReg(GR32, sub_8bit) -> GR32_ABCD.
The function will be used to compute register classes when emitting
INSERT_SUBREG and EXTRACT_SUBREG nodes and for register class inflation
of sub-register operations.
The version provided by TableGen is usually adequate, but targets can
override.
llvm-svn: 141142
The set of register classes should be closed under sub-register
operations and intersections. That will allow the register allocator to
model combinations of constraints accurately.
This patch implements the easiest form of register class inference: For
every register class, and for every sub-register SubIdx, the subset of
registers in RC that have a SubIdx sub-register should also be a register
class.
This does create some new register classes for the targets in the tree:
ARM gets a new QQQQPR_with_ssub_0. This class was omitted from the .td
file on purpose because it only has two registers. InstrEmitter and
RegisterCoalescer have safeguards against selecting too small register
classes, so it is harmless.
PowerPC gets a G8RC_with_sub_32 class because LR is not a sub_32
sub-register of LR8. I think that might be an omission?
X86 puts RIP in the GR64 class, and since that register doesn't have
8-bit sub-registers, we get:
GR64_with_sub_8bit
GR64_TC_with_sub_8bit
GR64_NOREX_with_sub_8bit
GR64_TC_with_sub_8bit_hi
The various CodeGen classes have already been fixed so adding new
register classes should not affect compile time.
llvm-svn: 141084
When TableGen starts creating its own register classes, the synthesized
classes won't have a Record reference. All register classes must have a
name, though.
llvm-svn: 141081
All register classes are given a lower ID than their sub-classes.
Cliques are ordered alphabetically.
This will be used to simplify some sub-class operations.
llvm-svn: 140826
Targets that need to change the default allocation order should use the
AltOrders mechanism instead. See the X86 and ARM targets for examples.
The allocation_order_begin() and allocation_order_end() methods have been
replaced with getRawAllocationOrder(), and there is further support
functions in RegisterClassInfo.
It is no longer possible to insert arbitrary code into generated
register classes. This is a feature.
llvm-svn: 133332
A register class can define AltOrders and AltOrderSelect instead of
defining method protos and bodies. The AltOrders lists can be defined
with set operations, and TableGen can verify that the alternative
allocation orders only contain valid registers.
This is currently an opt-in feature, and it is still possible to
override allocation_order_begin/end. That will not be true for long.
llvm-svn: 133320
This prepares tablegen to compute register lists from set theoretic dag
expressions. This doesn't really make any difference as long as
Target.td still declares RegisterClass::MemberList as [Register].
llvm-svn: 133043
Make the Elements vector private and expose an ArrayRef through
getOrder() instead. getOrder will eventually provide multiple
user-specified allocation orders.
Use the sorted member set for member and subclass tests. Clean up a lot
of ad hoc searches.
llvm-svn: 133040
Besides moving structural computations to CodeGenRegisters.cpp, this
also well-defines the order of these lists:
- Sub-register lists come from a pre-order traversal of the graph
defined by the SubRegs lists in the .td files.
- Super-register lists are topologically ordered so no register comes
before any of its sub-registers. When the sub-register graph is not a
tree, independent super-registers appear in numerical order.
- Lists of overlapping registers are ordered according to register
number.
This reverses the order of the super-regs lists, but nobody was
depending on that. The previous order of the overlaps lists was odd, and
it may have depended on the precise behavior of std::stable_sort.
The old computations are still there, but will be removed shortly.
llvm-svn: 132881
Some register classes are only used for instruction operand constraints.
They should never be used for virtual registers. Previously, those
register classes were given an empty allocation order, but now you can
say 'let isAllocatable=0' in the register class definition.
TableGen calculates if a register is part of any allocatable register
class, and makes that information available in TargetRegisterDesc::inAllocatableClass.
The goal here is to eliminate use cases for overriding allocation_order_*
methods.
llvm-svn: 132508
On the x86-64 and thumb2 targets, some registers are more expensive to encode
than others in the same register class.
Add a CostPerUse field to the TableGen register description, and make it
available from TRI->getCostPerUse. This represents the cost of a REX prefix or a
32-bit instruction encoding required by choosing a high register.
Teach the greedy register allocator to prefer cheap registers for busy live
ranges (as indicated by spill weight).
llvm-svn: 129864
structure that represents a mapping without any dependencies on SubRegIndex
numbering.
This brings us closer to being able to remove the explicit SubRegIndex
numbering, and it is now possible to specify any mapping without inventing
*_INVALID register classes.
llvm-svn: 104563
and better control the abstraction. Rename the type
to MVT. To update out-of-tree patches, the main
thing to do is to rename MVT::ValueType to MVT, and
rewrite expressions like MVT::getSizeInBits(VT) in
the form VT.getSizeInBits(). Use VT.getSimpleVT()
to extract a MVT::SimpleValueType for use in switch
statements (you will get an assert failure if VT is
an extended value type - these shouldn't exist after
type legalization).
This results in a small speedup of codegen and no
new testsuite failures (x86-64 linux).
llvm-svn: 52044
