some constant exprs to apints).
Thanks to Anton for tracking down a small testcase that triggered this!
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@35633 91177308-0d34-0410-b5e6-96231b3b80d8
isel has its own particular features that it wants in the CFG, in order to
reduce the number of times a constant is computed, etc. Make sure that we
clean up the CFG before doing any other things for isel. Doing so can
dramatically reduce the number of split edges and reduce the number of
places that constants get computed. For example, this shrinks
CodeGen/Generic/phi-immediate-factoring.ll from 44 to 37 instructions on X86,
and from 21 to 17 MBB's in the output. This is primarily a code size win,
not a performance win.
This implements CodeGen/Generic/phi-immediate-factoring.ll and PR1296.
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amount is safe.
2. Use new method on ConstantInt instead of (? :) operator.
3. Use new method uge() on ConstantInt to simplify codes.
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1. Line out nested call of APInt::zext/trunc.
2. Make more use of APInt::getHighBitsSet/getLowBitsSet.
3. Use APInt[] operator instead of expression like "APIntVal & SignBit".
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instead of using ConstantExpr::getXX.
2. Use constant reference to APInt if possible instead of expensive
APInt copy.
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2. Use APInt[] instead of "X & SignBit".
3. Clean up some codes.
4. Make the expression like "ShiftAmt = ShiftAmtC->getZExtValue()" safe.
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1. Line out nested use of zext/trunc.
2. Make more use of getHighBitsSet/getLowBitsSet.
3. Use APInt[] != 0 instead of "(APInt & SignBit) != 0".
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When converting an add/xor/and triplet into a trunc/sext, only do so if the
intermediate integer type is a bitwidth that the targets can handle.
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original and new instruction. A slight performance hit with ostringstream
but it is only for debug.
Also, clean up an uninitialized variable warning noticed in a release build.
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Fix SingleSource/Regression/C/2003-05-21-UnionBitFields.c by changing a
getHighBitsSet call to getLowBitsSet call that was incorrectly converted
from the original lshr constant expression.
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Remove a use of getLowBitsSet that caused the mask used for replacement of
shl/lshr pairs with an AND instruction to be computed incorrectly. Its not
clear exactly why this is the case. This solves the disappearing shifts
problem, but it doesn't fix Regression/C/2003-05-21-UnionBitFields. It
seems there is more going on.
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* Don't assume shift amounts are <= 64 bits
* Avoid creating an extra APInt in SubOne and AddOne by using -- and ++
* Add another use of getLowBitsSet
* Convert a series of if statements to a switch
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using the facilities of APInt. While this duplicates a tiny fraction of
the constant folding code, it also makes the code easier to read and
avoids large ConstantExpr overhead for simple, known computations.
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2. Use isStrictlyPositive() instead of isPositive() in two places where
they need APInt value > 0 not only >=0.
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* Convert the last use of a uint64_t that should have been an APInt.
* Change ComputeMaskedBits to have a const reference argument for the Mask
so that recursions don't cause unneeded temporaries. This causes temps
to be needed in other places (where the mask has to change) but this
change optimizes for the recursion which is more frequent.
* Remove two instances of &ing a Mask with getAllOnesValue. Its not
needed any more because APInt is accurate in its bit computations.
* Start using the getLowBitsSet and getHighBits set methods on APInt
instead of shifting. This makes it more clear in the code what is
going on.
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Convert some calls to ConstantInt::getZExtValue() into getValue() and
use APInt facilities in the subsequent computations.
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* APIntify visitAdd and visitSelectInst
* Remove unused uint64_t versions of utility functions that have been
replaced with APInt versions.
This completes most of the changes for APIntification of InstCombine. This
passes llvm-test and llvm/test/Transforms/InstCombine/APInt.
Patch by Zhou Sheng.
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* Re-enable the APInt version of MaskedValueIsZero.
* APIntify the Comput{Un}SignedMinMaxValuesFromKnownBits functions
* APIntify visitICmpInst.
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Analyze GEPs. If the indices are all zero, transfer whether the pointer is
known to be not null through the GEP.
Add a few more cases for xor and shift instructions.
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* Fix some indentation and comments in InsertRangeTest
* Add an "IsSigned" parameter to AddWithOverflow and make it handle signed
additions. Also, APIntify this function so it works with any bitwidth.
* For the icmp pred ([us]div %X, C1), C2 transforms, exit early if the
div instruction's RHS is zero.
* Finally, for icmp pred (sdiv %X, C1), -C2, fix an off-by-one error. The
HiBound needs to be incremented in order to get the range test correct.
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Add new micro-optimizations.
Add icmp predicate snuggling. Given %x ULT 4, "icmp ugt %x, 2" becomes
"icmp eq %x, 3". This doesn't apply in any non-trivial cases yet due to missing
support for NE values in ValueRanges.
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"APInt::getAllOnesValue(ShiftAmt).zextOrCopy(BitWidth)",
to handle ShiftAmt == BitWidth situation, use zextOrCopy() instead of
zext().
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1. Replace getSignedMinValue() with getSignBit() for better code readability.
2. Replace APIntOps::shl() with operator<<= for convenience.
3. Make APInt construction more effective.
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Provide an APIntified version of MaskedValueIsZero. This will (temporarily)
cause a "defined but not used" message from the compiler. It will be used
in the next patch in this series.
Patch by Sheng Zhou.
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Add a new ComputeMaskedBits function that is APIntified. We'll slowly
convert things over to use this version. When its all done, we'll remove
the existing version.
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scalarrepl things down to elements, but mem2reg can't promote elements that
are memset/memcpy'd. Until then, the code is disabled "0 &&".
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would scan the entire loop body, then scan all users of instructions in the
loop, looking for users outside the loop. Now, since we know that the
loop is in LCSSA form, we know that any users outside the loop will be LCSSA
phi nodes. Just scan them.
This speeds up indvars significantly.
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the order that instcombine processed instructions in the testcase. The end
result is that instcombine finished with:
define i16 @test1(i16 %a) {
%tmp = zext i16 %a to i32 ; <i32> [#uses=2]
%tmp21 = lshr i32 %tmp, 8 ; <i32> [#uses=1]
%tmp5 = shl i32 %tmp, 8 ; <i32> [#uses=1]
%tmp.upgrd.32 = or i32 %tmp21, %tmp5 ; <i32> [#uses=1]
%tmp.upgrd.3 = trunc i32 %tmp.upgrd.32 to i16 ; <i16> [#uses=1]
ret i16 %tmp.upgrd.3
}
which can't get matched as a bswap.
This patch makes instcombine more sophisticated about removing truncating
casts, allowing it to turn this into:
define i16 @test2(i16 %a) {
%tmp211 = lshr i16 %a, 8
%tmp52 = shl i16 %a, 8
%tmp.upgrd.323 = or i16 %tmp211, %tmp52
ret i16 %tmp.upgrd.323
}
which then matches as bswap. This fixes bswap.ll and implements
InstCombine/cast2.ll:test[12]. This also implements cast elimination of
add/sub.
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a value from the worklist required scanning the entire worklist to remove all
entries. We now use a combination map+vector to prevent duplicates from
happening and prevent the scan. This speeds up instcombine on a large file
from the llvm-gcc bootstrap from 189.7s to 4.84s in a debug build and from
5.04s to 1.37s in a release build.
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First round of ConstantRange changes. This makes all CR constructors use
only APInt and not use ConstantInt. Clients are adjusted accordingly.
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