Some platforms may treat denormals as zero, on other platforms multiplication
with a subnormal is slower than dividing by a normal.
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The idea is, that if an ieee 754 float is divided by a power of two, we can
turn the division into a cheaper multiplication. This function sees if we can
get an exact multiplicative inverse for a divisor and returns it if possible.
This is the hard part of PR9587.
I tested many inputs against llvm-gcc's frotend implementation of this
optimization and didn't find any difference. However, floating point is the
land of weird edge cases, so any review would be appreciated.
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of a constant had a minor typo introduced when copying it from the book, which
caused it to favor negative approximations over positive approximations in many
cases. Positive approximations require fewer operations beyond the multiplication.
In the case of division by 3, we still generate code that is a single instruction
larger than GCC's code.
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may be useful to understand "none", this is not the place for it. Tweak
the fix to Normalize while there: the fix added in 123990 works correctly,
but I like this way better. Finally, now that Triple understands some
non-trivial environment values, teach the unittests about them.
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This implementation already exists as ConnectedVNInfoEqClasses in
LiveInterval.cpp, and it seems to be generally useful to have a light-weight way
of forming equivalence classes of small integers.
IntEqClasses doesn't allow enumeration of the elements in a class.
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moves the iterator to end(), and it is valid to call it on end().
That means it is valid to call advanceTo() with any monotonic key sequence.
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editing of the current interval.
These methods may cause coalescing, there are corresponding set*Unchecked
methods for editing without coalescing. The non-coalescing methods are useful
for applying monotonic transforms to all keys or values in a map without
accidentally coalescing transformed and untransformed intervals.
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We always disallowed overlapping inserts with different values, and this makes
the insertion code smaller and faster.
If an overwriting insert is needed, it can be added as a separate method that
trims any existing intervals before inserting. The immediate use cases for
IntervalMap don't need this - they only use disjoint insertions.
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These iterators don't point anywhere, and they can't be compared to anything.
They are only good for assigning to.
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Implement iterator::erase() in a simple version that erases nodes when they
become empty, but doesn't try to redistribute elements among siblings for better
packing.
Handle coalescing across leaf nodes which may require erasing entries.
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to use lowercase letters for the start of most
method names and to replace some method names
with more descriptive names (e.g., "getLeft()"
instead of "Left()"). No real functionality
change.
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This is a sorted interval map data structure for small keys and values with
automatic coalescing and bidirectional iteration over coalesced intervals.
Except for coalescing intervals, it provides similar functionality to std::map.
It is however much more compact for small keys and values, and hopefully faster
too.
The container object itself can hold the first few intervals without any
allocations, then it switches to a cache conscious B+-tree representation. A
recycling allocator can be shared between many containers, even between
containers holding different types.
The IntervalMap is initially intended to be used with SlotIndex intervals for:
- Backing store for LiveIntervalUnion that is smaller and faster than std::set.
- Backing store for LiveInterval with less overhead than std::vector for typical
intervals and O(N log N) merging of large intervals. 99% of virtual registers
need 4 entries or less and would benefit from the small object optimization.
- Backing store for LiveDebugVariable which doesn't exist yet, but will track
debug variables during register allocation.
This is a work in progress. Missing items are:
- Performance metrics.
- erase().
- insert() shrinkage.
- clear().
- More performance metrics.
- Simplification and detemplatization.
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This is a sorted interval map data structure for small keys and values with
automatic coalescing and bidirectional iteration over coalesced intervals.
Except for coalescing intervals, it provides similar functionality to std::map.
It is however much more compact for small keys and values, and hopefully faster
too.
The container object itself can hold the first few intervals without any
allocations, then it switches to a cache conscious B+-tree representation. A
recycling allocator can be shared between many containers, even between
containers holding different types.
The IntervalMap is initially intended to be used with SlotIndex intervals for:
- Backing store for LiveIntervalUnion that is smaller and faster than std::set.
- Backing store for LiveInterval with less overhead than std::vector for typical
intervals and O(N log N) merging of large intervals. 99% of virtual registers
need 4 entries or less and would benefit from the small object optimization.
- Backing store for LiveDebugVariable which doesn't exist yet, but will track
debug variables during register allocation.
This is a work in progress. Missing items are:
- Performance metrics.
- erase().
- insert() shrinkage.
- clear().
- More performance metrics.
- Simplification and detemplatization.
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target triple and straightens it out. This does less than gcc's script
config.sub, for example it turns i386-mingw32 into i386--mingw32 not
i386-pc-mingw32, but it does a decent job of turning funky triples into
something that the rest of the Triple class can understand. The plan
is to use this to canonicalize triple's when they are first provided
by users, and have the rest of LLVM only deal with canonical triples.
Once this is done the special case workarounds in the Triple constructor
can be removed, making the class more regular and easier to use. The
comments and unittests for the Triple class are already adjusted in this
patch appropriately for this brave new world of increased uniformity.
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handles with a pointer to the containing map. When a map is copied, these
pointers need to be corrected to point to the new map. If not, then consider
the case of a map M1 which maps a value V to something. Create a copy M2 of
M1. At this point there are two value handles on V, one representing V as a
key in M1, the other representing V as a key in M2. But both value handles
point to M1 as the containing map. Now delete V. The value handles remove
themselves from their containing map (which destroys them), but only the first
value handle is successful: the second one cannot remove itself from M1 as
(once the first one has removed itself) there is nothing there to remove; it
is therefore not destroyed. This causes an assertion failure "All references
to V were not removed?".
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EXPECT_{TRUE,FALSE}(...) macros. This also prevents suprious warnings about
bool-to-pointer conversion that occurs withit EXPECT_EQ.
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- This can give substantial speedups in the delta process for inputs we can construct dependency information for.
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This means that our Registers are now ordered R7, R8, R9, R10, R12, ...
Not R1, R10, R11, R12, R2, R3, ...
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- This provides a convenient alternative to using something llvm::prior or
manual iterator access, for example::
if (T *Prev = foo->getPrevNode())
...
instead of::
iterator it(foo);
if (it != begin()) {
--it;
...
}
- Chris, please review.
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