There are a number of places that specially handle loads from a
uniform value where all the bits are the same (zero, one, undef,
poison), because we a) don't care about the load offset in that
case b) it bypasses casts that might not be legal generally but
do work with uniform values.
We had multiple implementations of this, with a different set of
supported values each time. This replaces two usages with a more
complete helper. Other usages will be replaced separately, because
they have larger impact.
This is part of D115924.
Global ctor evaluation currently models memory as a map from Constant*
to Constant*. For this to be correct, it is required that there is
only a single Constant* referencing a given memory location. The
Evaluator tries to ensure this by imposing certain limitations that
could result in ambiguities (by limiting types, casts and GEP formats),
but ultimately still fails, as can be seen in PR51879. The approach
is fundamentally fragile and will get more so with opaque pointers.
My original thought was to instead store memory for each global as an
offset => value representation. However, we also need to make sure
that we can actually rematerialize the modified global initializer
into a Constant in the end, which may not be possible if we allow
arbitrary writes.
What this patch does instead is to represent globals as a MutableValue,
which is either a Constant* or a MutableAggregate*. The mutable
aggregate exists to allow efficient mutation of individual aggregate
elements, as mutating an element on a Constant would require interning
a new constant. When a write to the Constant* is made, it is converted
into a MutableAggregate* as needed.
I believe this should make the evaluator more robust, compatible
with opaque pointers, and a bit simpler as well.
Fixes https://github.com/llvm/llvm-project/issues/51221.
Differential Revision: https://reviews.llvm.org/D115530
This fixes the assertion failure reported at
https://reviews.llvm.org/D114889#3198921 with a straightforward
check, until the cleaner fix in D115924 can be reapplied.
This reverts commit 9fd4f80e33a4ae4567483819646650f5735286e2.
This breaks SingleSource/Regression/C/gcc-c-torture/execute/pr19687.c
in test-suite. Either the test is incorrect, or clang is generating
incorrect union initialization code. I've submitted
https://reviews.llvm.org/D115994 to fix the test, assuming my
interpretation is correct. Reverting this in the meantime as it
may take some time to resolve.
There are a number of places that specially handle loads from a
uniform value where all the bits are the same (zero, one, undef,
poison), because we a) don't care about the load offset in that
case and b) it bypasses casts that might not be legal generally
but do work with uniform values.
We had multiple implementations of this, with a different set of
supported values each time, as well as incomplete type checks in
some cases. In particular, this fixes the assertion reported in
https://reviews.llvm.org/D114889#3198921, as well as a similar
assertion that could be triggered via constant folding.
Differential Revision: https://reviews.llvm.org/D115924
This bases the CleanupConstantGlobalUsers() implementation around
the ConstantFoldLoadFromConst() API. The general approach is that
we discover all users while looking through casts, and then
constant fold loads and drop stores and memintrinsics.
This avoids special cases and limitations in the previous
implementation, which is also incompatible with opaque pointers.
The result is a bit more powerful than before, because we now use
more general load folding logic which can for example look through
pointer bitcasts between different sizes. This is where the test
changes come from, as we now fold more loads and can thus remove
more globals.
Differential Revision: https://reviews.llvm.org/D114889
createReplacementInstr was a trivial wrapper around
ConstantExpr::getAsInstruction, which also inserted the new instruction
into a basic block. Implement this directly in getAsInstruction by
adding an InsertBefore parameter and change all callers to use it. NFC.
A follow-up patch will remove createReplacementInstr.
Differential Revision: https://reviews.llvm.org/D112791
This patch continues unblocking optimizations that are blocked by pseudo probe instrumentation.
Not exactly like DbgIntrinsics, PseudoProbe intrinsic has other attributes (such as mayread, maywrite, mayhaveSideEffect) that can block optimizations. The issues fixed are:
- Flipped default param of getFirstNonPHIOrDbg API to skip pseudo probes
- Unblocked CSE by avoiding pseudo probe from clobbering memory SSA
- Unblocked induction variable simpliciation
- Allow empty loop deletion by treating probe intrinsic isDroppable
- Some refactoring.
Reviewed By: wenlei
Differential Revision: https://reviews.llvm.org/D110847
Do not call `TryToShrinkGlobalToBoolean` for address spaces
that don't allow initializers. It inserts an initializer value
while shrinking to bool. Used the target hook introduced with
D109337 to skip this call for the restricted address spaces.
Reviewed By: tra
Differential Revision: https://reviews.llvm.org/D109823
This reapplies commit 7dbba3376f633cabcf4df568bc9ca95f44a35203, or, put
differently, this reverts commit d9a8d20827dcddad831751bc38ff178e70f0b2f5.
The test now requires the amdgpu and nvptx backend explicitly as it
won't work without properly.
Not all address spaces support initializers for globals and we can
therefore not set them without checking if they are allowed. This
patch adds a hook into TTI to check if an AS allows non-undef
initializers. We disable it for all but address space 0 by default,
NVPTX and AMDGPU targets allow all but address space 3.
Reviewed By: tra
Differential Revision: https://reviews.llvm.org/D109337
We try to forward a stored-once-constant-value from one global access
to another, but that's not safe if the constant value is an expression
that can trap.
The tests are reduced from the miscompile examples in:
https://llvm.org/PR47578
Differential Revision: https://reviews.llvm.org/D108771
In the provided test case, we were trying to set the global's
initializer to `i32* null` when the global's value type was `@0`.
Reviewed By: rnk
Differential Revision: https://reviews.llvm.org/D108232
Currently, in OptimizeGlobalAddressOfMalloc, the transformation for global loads assumes that they have the same Type. With the support of ConstantExpr (https://reviews.llvm.org/D106589), this may not be true any more (as seen in the test case), and we miss the code to handle this, This is to fix that.
Reviewed By: efriedma
Differential Revision: https://reviews.llvm.org/D107397
I'm working on extending the OptimizeGlobalAddressOfMalloc to handle some more general cases. This is to add support of the ConstantExpr use of the global variables. The function allUsesOfLoadedValueWillTrapIfNull is now iterative with the added CE use of GV. Also, the recursive function valueIsOnlyUsedLocallyOrStoredToOneGlobal is changed to iterative using a worklist with the GEP case added.
Reviewed By: efriedma
Differential Revision: https://reviews.llvm.org/D106589
GlobalOpt can slice structs/arrays and change GEPs in the process,
but it was not updating alignments for load/store users. This
eventually causes the crashing seen in:
https://llvm.org/PR49661https://llvm.org/PR50253
On x86, this required SLP+codegen to create an aligned vector
store on an invalid address. The bugs would be easier to
demonstrate on a target with stricter alignment requirements.
I'm not sure if this is a complete solution. The alignment
updating code is adapted from InstCombine, so I assume that
part is tested and good.
Differential Revision: https://reviews.llvm.org/D102552
GlobalOpt implements a heap SROA (SROA for an malloc allocatated struct or array
of structs) which is largely undertested (heap-sra-[1234].ll are basically the
same test with very little difference) and does not trigger at all when
bootstrapping clang (it only supports the case of one single store).
The heap SROA implementation causes PR50027 (GEP is not properly handled; crash or miscompile).
Just drop the implementation. I have deleted some obviously duplicated tests
but kept `heap-sra-[12]{,-no-nullopt}.ll`.
Reviewed By: aeubanks
Differential Revision: https://reviews.llvm.org/D102257
Both the alias and aliasee linkage are important.
PR27866 provides some background.
Reviewed By: rnk
Differential Revision: https://reviews.llvm.org/D99629
Previously we would use the type of the pointee to determine what to
cast the result of constant folding a load. To aid with opaque pointer
types, we should explicitly pass the type of the load rather than
looking at pointee types.
ConstantFoldLoadThroughBitcast() converts the const prop'd value to the
proper load type (e.g. [1 x i32] -> i32). Instead of calling this in
every intermediate step like bitcasts, we only call this when we
actually see the global initializer value.
In some existing uses of this API, we don't know the exact type we're
loading from immediately (e.g. first we visit a bitcast, then we visit
the load using the bitcast). In those cases we have to manually call
ConstantFoldLoadThroughBitcast() when simplifying the load to make sure
that we cast to the proper type.
Reviewed By: dblaikie
Differential Revision: https://reviews.llvm.org/D100718
This patch enhances hasAddressTaken() to ignore bitcasts as a
callee in callbase instruction. Such bitcast usage doesn't really take
the address in a useful meaningful way.
Reviewed By: rampitec
Differential Revision: https://reviews.llvm.org/D98884
And delete the SmallPtrSetImpl overload.
While here, decrease inline element counts from 8 to 4. See D97128 for the choice.
Reviewed By: tejohnson
Differential Revision: https://reviews.llvm.org/D97257
Use isKnownXY comparators when one of the operands can be with
scalable vectors or getFixedSize() for all the other cases.
This patch also does bug fixes for getPrimitiveSizeInBits by using
getFixedSize() near the places with the TypeSize comparison.
Differential Revision: https://reviews.llvm.org/D89703
When marking a global variable constant, and simplifying users using
CleanupConstantGlobalUsers(), the pass could incorrectly return false if
there were still some uses left, and no further optimizations was done.
This was caught using the check introduced by D80916.
This fixes PR46749.
Reviewed By: fhahn
Differential Revision: https://reviews.llvm.org/D85837
When removing a non-constant store to a global in
CleanupPointerRootUsers(), the GlobalOpt pass could incorrectly return
false.
This was caught using the check introduced by D80916.
Reviewed By: efriedma
Differential Revision: https://reviews.llvm.org/D86149
When turning on -debug-info-kind=constructor we ran into a "fragment covers
entire variable" error during thinlto. The fragment is currently always
emitted if there is no type size, but sometimes the variable has a
forward declared struct type which doesn't have a size.
This changes the code to get the type size from the GlobalVariable instead.
Differential Revision: https://reviews.llvm.org/D85572
Summary:
It is reasonably common to want to clone some call with different bundles.
Let's actually provide an interface to do that.
Reviewers: chandlerc, jdoerfert, dblaikie, nickdesaulniers
Reviewed By: nickdesaulniers
Subscribers: llvm-commits, hiraditya
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D83248
