can be used to turn a <4 x i64> into a <4 x i32> but getCastOpcode would assert
if you passed these types to it. Note that this strictly extends the previous
functionality: if getCastOpcode previously accepted two vector types (i.e. didn't
assert) then it still will and returns the same opcode (BitCast). That's because
before it would only accept vectors with the same bitwidth, and the new code only
touches vectors with the same length. However if two vectors have both the same
bitwidth and the same length then their element types have the same bitwidth, so
the new logic will return BitCast as before.
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had gotten out of sync: isCastable didn't think it was possible to
cast the x86_mmx type to anything, while it did think it possible
to cast an i64 to x86_mmx.
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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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should be that if the phi is used by a side-effect free instruction with
no uses then the phi and the instruction now get zapped (checked by the
unittest).
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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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test for that. With this change, test/CodeGen/X86/codegen-dce.ll no longer finds
any instructions to DCE, so delete the test.
Also renamed J and JP to I and IP in RecursivelyDeleteDeadPHINode.
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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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Add a unnamed_addr bit to global variables and functions. This will be used
to indicate that the address is not significant and therefore the constant
or function can be merged with others.
If an optimization pass can show that an address is not used, it can set this.
Examples of things that can have this set by the FE are globals created to
hold string literals and C++ constructors.
Adding unnamed_addr to a non-const global should have no effect unless
an optimization can transform that global into a constant.
Aliases are not allowed to have unnamed_addr since I couldn't figure
out any use for it.
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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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