When LivePhysRegs adds live-in registers, it recognizes ~0 as a special
lane mask indicating the entire register. If the lane mask is not ~0,
it will only add the subregisters that overlap the specified lane mask.
The problem is that if a live-in register does not have subregisters,
and the lane mask is not ~0, it will not be added to the live set.
(The given lane mask may simply be the lane mask of its register class.)
If a register does not have subregisters, add it to the live set if
the lane mask is non-zero.
Differential Revision: https://reviews.llvm.org/D26094
llvm-svn: 285440
Do not use LiveIntervals to recalculate kills, because that cannot be
done accurately without implicit uses on predicated instructions.
llvm-svn: 285409
After register allocation it is possible to have a spill of a register
that is only partially defined. That in itself it fine, but creates a
problem for double vector registers. Stores of such registers are pseudo
instructions that are expanded into pairs of individual vector stores,
and in case of a partially defined source, one of the stores may use
an entirely undefined register. To avoid this, track the defined parts
and only generate actual stores for those.
llvm-svn: 284841
This required reengineering of some of the part of liveness calculation,
including fixing some issues caused by the limitations of the previous
approach. The current code is not necessarily the fastest, but it should
be functionally correct (at least more so than before). The compile-time
performance will be addressed in the future.
llvm-svn: 284609
Branch folder removes implicit defs if they are the only non-branching
instructions in a block, and the branches do not use the defined registers.
The problem is that in some cases these implicit defs are required for
the liveness information to be correct.
Differential Revision: https://reviews.llvm.org/D25478
llvm-svn: 284036
This avoids llc using the hosts OS/vendor as defaults and triggering
unwanted behaviour in the tests. This should deal with the buildbot
breakages on windows after r283140.
llvm-svn: 283149
Each shadow only represents data flow that is restricted to its reaching
def. Propagating more than that could lead to spurious register liveness,
resulting in extra (incorrectly) block live-ins.
llvm-svn: 283143
Normally, if conversion would add implicit uses for redefined registers,
e.g. R0<def> = add_if ..., R0<imp-use>. However, if only subregisters of
R0 are known to be live but not R0 itself, such implicit uses will not be
added, causing prior definitions of such subregisters and R0 itself to
become dead.
llvm-svn: 282626
descriptions now tag add instructions, and the Hexagon backend is using this to
identify loop induction statements.
Patch by Sam Parker and Sjoerd Meijer.
Differential Revision: https://reviews.llvm.org/D23601
llvm-svn: 281304
Shadow uses need to be analyzed together, since each individual shadow
will only have a partial reaching def. All shadows together may cover
a given register ref, while each individual shadow may not.
llvm-svn: 280855
This reverts commit r280268, it causes all MSVC 2013 to ICE. This
appears to have been fixed in a later MSVC 2013 update, because I cannot
reproduce it locally. That said, all upstream LLVM bots are broken right
now, so I am reverting.
Also reverts dependent change r280275, "[Hexagon] Deal with undefs when
extending live intervals".
llvm-svn: 280301
This bug shows up with diamonds that share unpredicable, unanalyzable branches.
There's an included test case from Hexagon. What was happening was that we were
attempting to predicate the branch instruction despite the fact that it was
checked to be the same. Now for unanalyzable branches we skip over the branch
instructions when predicating the block.
Differential Revision: https://reviews.llvm.org/D23939
llvm-svn: 279985
Rename AllVRegsAllocated to NoVRegs. This avoids the connotation of
running after register and simply describes that no vregs are used in
a machine function. With that we can simply compute the property and do
not need to dump/parse it in .mir files.
Differential Revision: http://reviews.llvm.org/D23850
llvm-svn: 279698
The register allocator can split a live interval of a register into a set
of smaller intervals. After the allocation of registers is complete, the
rewriter will modify the IR to replace virtual registers with the corres-
ponding physical registers. At this stage, if a register corresponding
to a subregister of a virtual register is used, the rewriter will check
if that subregister is undefined, and if so, it will add the <undef> flag
to the machine operand. The function verifying liveness of the subregis-
ter would assume that it is undefined, unless any of the subranges of the
live interval proves otherwise.
The problem is that the live intervals created during splitting do not
have any subranges, even if the original parent interval did. This could
result in the <undef> flag placed on a register that is actually defined.
Differential Revision: http://reviews.llvm.org/D21189
llvm-svn: 279625
Improved handling of fma, floating point min/max, additional load/store
instructions for floating point types.
Patch by Jyotsna Verma.
llvm-svn: 279239
The pipeliner was generating an invalid Phi name for an operand
in the epilog block, which caused an assert in the live variable
analysis pass. The fix is to the code that generates new Phis
in the epilog block. In this case, there is an existing Phi that
needs to be reused rather than creating a new Phi instruction.
Differential Revision: https://reviews.llvm.org/D23513
llvm-svn: 278805
If a loop is not rotated (for example when optimizing for size), the latch is not the backedge. If we promote an expression to post-inc form, we not only increase register pressure and add a COPY for that IV expression but for all IVs!
Motivating testcase:
void f(float *a, float *b, float *c, int n) {
while (n-- > 0)
*c++ = *a++ + *b++;
}
It's imperative that the pointer increments be located in the latch block and not the header block; if not, we cannot use post-increment loads and stores and we have to keep both the post-inc and pre-inc values around until the end of the latch which bloats register usage.
llvm-svn: 278658
Krzysztof Parzyszek