This handles the case where we have an inbounds GEP with alloca as the pointer.
This fixes the regression in PR12750 and rdar://13286434.
Note that we can also fix this by handling some GEP cases in isKnownNonNull.
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isn't using the default calling convention. However, if the transformation is
from a call to inline IR, then the calling convention doesn't matter.
rdar://13157990
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Prepare it for vectors of pointers and handle simple cases. We don't handle
complicated cases because accumulateConstantOffset bails on pointer vectors.
Fixes selfhost on i386.
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remaining use of AliasAnalysis concepts such as isIdentifiedObject to
prove pointer inequality.
@external_compare in test/Transforms/InstSimplify/compare.ll shows a simple
case where a noalias argument can be equal to a global variable address, and
while AliasAnalysis can get away with saying that these pointers don't alias,
instsimplify cannot say that they are not equal.
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be equal, since there's nothing preventing a caller from correctly predicting
the stack location of an alloca.
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constant folding calls. Add the initial tests for this which show that
now instsimplify can simplify blindingly obvious code patterns expressed
with both intrinsics and library calls.
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fsub X, +0 ==> X
fsub X, -0 ==> X, when we know X is not -0
fsub +/-0.0, (fsub -0.0, X) ==> X
fsub nsz +/-0.0, (fsub +/-0.0, X) ==> X
fsub nnan ninf X, X ==> 0.0
fadd nsz X, 0 ==> X
fadd [nnan ninf] X, (fsub [nnan ninf] 0, X) ==> 0
where nnan and ninf have to occur at least once somewhere in this expression
fmul X, 1.0 ==> X
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by virtue of inbounds GEPs that preclude a null pointer.
This is a very common pattern in the code generated by std::vector and
other standard library routines which use allocators that test for null
pervasively. This is one step closer to teaching Clang+LLVM to be able
to produce an empty function for:
void f() {
std::vector<int> v;
v.push_back(1);
v.push_back(2);
v.push_back(3);
v.push_back(4);
}
Which is related to getting them to completely fold SmallVector
push_back sequences into constants when inlining and other optimizations
make that a possibility.
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Original commit message for r153521 (aka r153423):
Use the new range metadata in computeMaskedBits and add a new optimization to
instruction simplify that lets us remove an and when loding a boolean value.
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undefined behavior, which Rafael was kind enough to fix.
Original commit message for r153423:
Use the new range metadata in computeMaskedBits and add a new optimization to
instruction simplify that lets us remove an and when loding a boolean value.
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Original commit message:
Use the new range metadata in computeMaskedBits and add a new optimization to
instruction simplify that lets us remove an and when loading a boolean value.
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constant-offsets of a common base using the generic GEP-walking logic
I added for computing pointer differences in the same situation.
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inbounds GEPs. This isn't really necessary for simplifying pointer
differences, but I'm planning to re-use the same code to simplify
pointer comparisons where it is necessary. Since real code almost
exclusively uses inbounds GEPs, it doesn't seem worth it to support the
extra complexity of turning it on and off. If anyone would like that
back, feel free to shout. Note that instcombine will still catch any of
these patterns.
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Typically instcombine has handled this, but pointer differences show up
in several contexts where we would like to get constant folding, and
cannot afford to run instcombine. Specifically, I'm working on improving
the constant folding of arguments used in inline cost analysis with
instsimplify.
Doing this in instsimplify implies some algorithm changes. We have to
handle multiple layers of all-constant GEPs because instsimplify cannot
fold them into a single GEP the way instcombine can. Also, we're only
interested in all-constant GEPs. The result is that this doesn't really
replace the instcombine logic, it's just complimentary and focused on
constant folding.
Reviewed on IRC by Benjamin Kramer.
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by using llvm::isIdentifiedObject. Also teach it to handle GEPs that have
the same base pointer and constant operands. Fixes PR11238!
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is that patterns no longer match for vectors of booleans, because you only get
ConstantDataVector when the vector element type is i8, i16, etc, not when it is
i1). Original commit message:
Remove some dead code and tidy things up now that vectors use ConstantDataVector
instead of always using ConstantVector.
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and positive: positive, because it could be directly computed to be positive;
negative, because the nsw flags means it is either negative or undefined (the
multiplication always overflowed).
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with the given predicate, it matches any condition and returns the
predicate - d'oh! Original commit message:
The expression icmp eq (select (icmp eq x, 0), 1, x), 0 folds to false.
Spotted by my super-optimizer in 186.crafty and 450.soplex. We really
need a proper infrastructure for handling generalizations of this kind
of thing (which occur a lot), however this case is so simple that I decided
to go ahead and implement it directly.
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Spotted by my super-optimizer in 186.crafty and 450.soplex. We really
need a proper infrastructure for handling generalizations of this kind
of thing (which occur a lot), however this case is so simple that I decided
to go ahead and implement it directly.
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using BinaryOperator (which only works for instructions) when it should have
been a cast to OverflowingBinaryOperator (which also works for constants).
While there, correct a few other dubious looking uses of BinaryOperator.
Thanks to Chad Rosier for the testcase. Original commit message:
My super-optimizer noticed that we weren't folding this expression to
true: (x *nsw x) sgt 0, where x = (y | 1). This occurs in 464.h264ref.
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