This is primarily to reduce stack usage, but ordering the use queue
according to the position in the code (earlier instructions visited
before later ones) reduces the number of unnecessary bottoms due to
visiting instructions out of order, e.g.
%reg1 = copy %reg0
%reg2 = copy %reg0
%reg3 = and %reg1, %reg2
Here, reg3 should be known to be same as reg0-2, but if reg3 is
evaluated after reg1 is updated, but before reg2 is updated, the two
inputs to the and will appear different, causing reg3 to become
bottom.
llvm-svn: 320866
Add two callbacks to MachineEvaluator, so that specific implementations
can specify more details about register classes:
- composeWithSubRegIndex(RC,Idx), to provide the register class for a
register from RC used in conjunction with a subregister index Idx.
- getPhysRegBitWidth(Reg), to provide the size in bits of the given
physical register.
llvm-svn: 314136
In the bit tracker, references to other bit values in which the register
is 0 are prohibited. This means that generating self-referential register
cells like { w:32 [0-15]:s[0-15] [16-31]:s[15] } is impossible. In order
to get a self-referential cell, it had to be stored into a map and then
reloaded from it. To avoid this step, add a function that will set the
register to a given value without going through the map.
llvm-svn: 296025
Consider this case:
vreg1 = A2_zxth vreg0 (1)
...
vreg2 = A2_zxth vreg1 (2)
Redundant instruction elimination could delete the instruction (1)
because the user (2) only cares about the low 16 bits. Then it could
delete (2) because the input is already zero-extended. The problem
is that the properties allowing each individual instruction to be
deleted depend on the existence of the other instruction, so either
one can be deleted, but not both.
The existing check for this situation in RIE was insufficient. The
fix is to update all dependent cells when an instruction is removed
(replaced via COPY) in RIE.
llvm-svn: 276792
Avoid implicit iterator conversions from MachineInstrBundleIterator to
MachineInstr* in the Hexagon backend, mostly by preferring MachineInstr&
over MachineInstr* and switching to range-based for loops.
There's a long tail of API cleanup here, but I'm planning to leave the
rest to the Hexagon maintainers. HexagonInstrInfo defines many of its
own predicates, and most of them still take MachineInstr*. Some of
those actually check for nullptr, so I didn't feel comfortable changing
them to MachineInstr& en masse.
llvm-svn: 275142
Remove some unnecessary explicit special members in Hexagon that, once
removed, allow the other implicit special members to be used without
depending on deprecated features.
llvm-svn: 243825
The standard containers are not designed to be inherited from, as
illustrated by the MSVC hacks for NodeOrdering. No functional change
intended.
llvm-svn: 242616
This includes code that is intended to be target-independent as well
as the Hexagon-specific details. This is just the framework without
any users.
llvm-svn: 241595
