The <undef> flag says that a MachineOperand doesn't read its register,
or doesn't depend on the previous value of its register.
A full register def never depends on the previous register value. A
partial register def may depend on the previous value if it is intended
to update part of a register.
For example:
%vreg10:dsub_0<def,undef> = COPY %vreg1
%vreg10:dsub_1<def> = COPY %vreg2
The first copy instruction defines the full %vreg10 register with the
bits not covered by dsub_0 defined as <undef>. It is not considered a
read of %vreg10.
The second copy modifies part of %vreg10 while preserving the rest. It
has an implicit read of %vreg10.
This patch adds a MachineOperand::readsReg() method to determine if an
operand reads its register.
Previously, this was modelled by adding a full-register <imp-def>
operand to the instruction. This approach makes it possible to
determine directly from a MachineOperand if it reads its register. No
scanning of MI operands is required.
llvm-svn: 141124
Add a test to do list manipulation and pass the result as arguments.
This tests the new list element operator resolve code and provides an
example of using list manipulation to do instruction pattern
substitution.
llvm-svn: 141102
When resolving an operator list element reference, resolve all
operator operands and try to fold the operator first. This allows the
operator to collapse to a list which may then be indexed.
Before, it was not possible to do this:
class D<int a, int b> { ... }
class C<list<int> A> : D<A[0], A[1]>;
class B<list<int> b> : C<!foreach(...,b)>;
Now it is.
llvm-svn: 141101
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
This patch adds a preprocessor that can expand nested for-loops for
saving some copy-n-paste in *.td files.
The preprocessor is not yet integrated with TGParser, and so it has
no direct effect on *.td inputs. However, you may preprocess an td
input (and only preprocess it).
To test the proprecessor, type:
tblgen -E -o $@ $<
llvm-svn: 141079
This handles the case in which LSR rewrites an IV user that is a phi and
splits critical edges originating from a switch.
Fixes <rdar://problem/6453893> LSR is not splitting edges "nicely"
llvm-svn: 141059
This code will replace the version in ARMAsmPrinter.cpp. It creates a new
machine basic block, which is the dispatch for the return from a longjmp
call. It then shoves the address of that machine basic block into the correct
place in the function context so that the EH runtime will jump to it directly
instead of having to go through a compare-and-jump-to-the-dispatch bit. This
should be more efficient in the common case.
llvm-svn: 141031
Bill Wendling