Patch by Michele Scandale!
Rewrite of the functions used to compute the backedge taken count of a
loop on LT and GT comparisons.
I decided to split the handling of LT and GT cases becasue the trick
"a > b == -a < -b" in some cases prevents the trip count computation
due to the multiplication by -1 on the two operands of the
comparison. This issue comes from the conservative computation of
value range of SCEVs: taking the negative SCEV of an expression that
have a small positive range (e.g. [0,31]), we would have a SCEV with a
fullset as value range.
Indeed, in the new rewritten function I tried to better handle the
maximum backedge taken count computation when MAX/MIN expression are
used to handle the cases where no entry guard is found.
Some test have been modified in order to check the new value correctly
(I manually check them and reasoning on possible overflow the new
values seem correct).
I finally added a new test case related to the multiplication by -1
issue on GT comparisons.
llvm-svn: 194116
One of the uses of the IsValid flag is to support default constructing
a ErrorOr that is not a Error or a Value. There is not much value in
doing that IMHO. If ErrorOr was to have a default constructor, it
should be implemented by default constructing the value, but even that
looks unnecessary.
The other use is to avoid calling destructors on moved objects. This
looks wrong. If the data being moved has non trivial treatment of
moves (an std::vector for example), it is its destructor that should
handle it, not ~ErrorOr.
With this change ErrorOr becomes a fairly simple wrapper and should
always be better than using an error_code + value in an API.
llvm-svn: 194109
MorphNodeTo is not safe to call during DAG building. It eagerly
deletes dependent DAG nodes which invalidates the NodeMap. We could
expose a safe interface for morphing nodes, but I don't think it's
worth it. Just create a new MachineNode and replaceAllUsesWith.
My understaning of the SD design has been that we want to support
early target opcode selection. That isn't very well supported, but
generally works. It seems reasonable to rely on this feature even if
it isn't widely used.
llvm-svn: 194102
we don't have such an operand.
Suprisingly enough, this is never actually accounted for in the
ARM version when determining offset ranges. In both places there is the
comment:
- // FIXME: Make use full range of soimm values.
(soimm = shift operand immediate).
llvm-svn: 194101
Cortex-M0 supports these 32-bit instructions despite being Thumb1 only
(mostly). We knew about that but not that the aliases without the default "sy"
operand were also permitted.
llvm-svn: 194094
Due to the previously added overflow checks, we can have a retain/release
relation that is one directional. This occurs specifically when we run into an
additive overflow causing us to drop state in only one direction. If that
occurs, we should bail and not optimize that retain/release instead of
asserting.
Apologies for the size of the testcase. It is necessary to cause the additive
cfg overflow to trigger.
rdar://15377890
llvm-svn: 194083
Submit the basic port of the rest of ARM constant islands code to Mips.
Two test cases are added which reflect the next level of functionality:
constants getting moved to water areas that are out of range from the
initial placement at the end of the function and basic blocks being split to
create water when none exists that can be used. There is a bunch of this
code that is not complete and has been marked with IN_PROGRESS. I will
finish cleaning this all up during the next week or two and submit the
rest of the test cases. I have elminated some code for dealing with
inline assembly because to me it unecessarily complicates things and
some of the newer features of llvm like function attributies and builtin
assembler give me better tools to solve the alignment issues created
there. Also, for Mips16 I even have the option of not doing constant
islands in the present of inline assembler if I chose. When everything
has been completed I will summarize the port and notify people that
are knowledgable regarding the ARM Constant Islands code so they can
review it in it's entirety if they wish.
llvm-svn: 194053
This patch enables llvm-cov to correctly output the run count stored in
the GCDA file. GCOVProfiling currently does not generate this
information, so the GCDA run data had to be hacked on from a GCDA file
generated by gcc. This is corrected by a subsequent patch.
With the run and program data included, both llvm-cov and gcov produced
the same output.
llvm-svn: 194033
ErrorOr had quiet a bit of complexity and indirection to be able to hold a user
type with the error.
That feature is not used anymore. This patch removes it, it will live in svn
history if we ever need it again.
If we do need it again, IMHO there is one thing that should be done
differently: Holding extra info in the error is not a property a function also
returning a value or not. The ability to hold extra info should be in the error
type and ErrorOr templated over it so that we don't need the funny looking
ErrorOr<void>.
llvm-svn: 194030
