transformation much more careful. Truncating binary '01' to '1' sounds like it's
safe until you realize that it switched from positive to negative under a signed
interpretation, and that depends on the icmp predicate.
Also a few miscellaneous cleanups.
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operators.
The test difference is just due to the multiplication operands
being commuted (and thus requiring a more elaborate match). In
optimized code, that expression would be folded.
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and T->isPointerTy(). Convert most instances of the first form to the second form.
Requested by Chris.
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cases, and implement target-independent folding rules for alignof and
offsetof. Also, reassociate reassociative operators when it leads to
more folding.
Generalize ScalarEvolution's isOffsetOf to recognize offsetof on
arrays. Rename getAllocSizeExpr to getSizeOfExpr, and getFieldOffsetExpr
to getOffsetOfExpr, for consistency with analagous ConstantExpr routines.
Make the target-dependent folder promote GEP array indices to
pointer-sized integers, to make implicit casting explicit and exposed
to subsequent folding.
And add a bunch of testcases for this new functionality, and a bunch
of related existing functionality.
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getelementptr (i8* inttoptr (i64 1 to i8*), i32 -1)
to
inttoptr (i64 0 to i8*)
from the VMCore constant folder. It didn't handle sign-extension properly
in the case where the source integer is smaller than a pointer size. And,
it relied on an assumption about sizeof(i8).
The Analysis constant folder still folds these kinds of things; it has
access to TargetData, so it can do them right.
Add a testcase which tests that the VMCore constant folder doesn't
miscompile this, and that the Analysis folder does fold it.
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use plain SCEVUnknowns with ConstantExpr::getSizeOf and
ConstantExpr::getOffsetOf constants. This eliminates a bunch of
special-case code.
Also add code for pattern-matching these expressions, for clients that
want to recognize them.
Move ScalarEvolution's logic for expanding array and vector sizeof
expressions into an element count times the element size, to expose
the multiplication to subsequent folding, into the regular constant
folder.
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if one of the vectors didn't have elements (such as undef). Fixes PR 6096.
Fix an issue in the constant folder where fcmp (<2 x %ty>, <2 x %ty>) would
have <2 x i1> type if constant folding was successful and i1 type if it wasn't.
This exposed a related issue in the bitcode reader.
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In the new world order, BlockAddress can have a BasicBlock operand.
This doesn't permute much, because if you have a ConstantExpr (or
anything more specific than Constant) we still know the operand has
to be a Constant.
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allowing it to simplify the crazy constantexprs in the testcases
down to something sensible. This allows -std-compile-opts to
completely "devirtualize" the pointers to member functions in
the testcase from PR5176.
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the new predicates I added) instead of going through a context and doing a
pointer comparison. Besides being cheaper, this allows a smart compiler
to turn the if sequence into a switch.
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Add another line to the ConstantExprFold test to demonstrate the GEPs may not
wrap around in either the signed or unsigned senses.
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how to fold notionally-out-of-bounds array getelementptr indices instead
of just doing these in lib/Analysis/ConstantFolding.cpp, because it can
be done in a fairly general way without TargetData, and because not all
constants are visited by lib/Analysis/ConstantFolding.cpp. This enables
more constant folding.
Also, set the "inbounds" flag when the getelementptr indices are
one-past-the-end.
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within the notional bounds of the static type of the getelementptr (which
is not the same as "inbounds") from GlobalOpt into a utility routine,
and use it in ConstantFold.cpp to check whether there are any mis-behaved
indices.
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and exact flags. Because ConstantExprs are uniqued, creating an
expression with this flag causes all expressions with the same operands
to have the same flag, which may not be safe. Add, sub, mul, and sdiv
ConstantExprs are usually folded anyway, so the main interesting flag
here is inbounds, and the constant folder already knows how to set the
inbounds flag automatically in most cases, so there isn't an urgent need
for the API support.
This can be reconsidered in the future, but for now just removing these
API bits eliminates a source of potential trouble with little downside.
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