Drop the requirement that getInitialValueOfAllocation() must be
passed an allocator function, shifting the responsibility for
checking that into the function (which it does anyway). The
motivation is to avoid some calls to isAllocationFn(), which has
somewhat ill-defined semantics (given the number of
allocator-related attributes we have floating around...)
(For this function, all we eventually need is an allockind of
zeroed or uninitialized.)
Differential Revision: https://reviews.llvm.org/D127274
Most clients only used these methods because they wanted to be able to
extend or truncate to the same bit width (which is a no-op). Now that
the standard zext, sext and trunc allow this, there is no reason to use
the OrSelf versions.
The OrSelf versions additionally have the strange behaviour of allowing
extending to a *smaller* width, or truncating to a *larger* width, which
are also treated as no-ops. A small amount of client code relied on this
(ConstantRange::castOp and MicrosoftCXXNameMangler::mangleNumber) and
needed rewriting.
Differential Revision: https://reviews.llvm.org/D125557
Per feedback on D123086 after submit.
Also added a test for vec_malloc et al attribute inference to show it's
doing the right thing.
The new tests exposed a defect, corrected by adding vec_free to the list of
free functions in MemoryBuiltins.cpp, which had been overlooked all the
way back in D94710, over a year ago.
Differential Revision: https://reviews.llvm.org/D124859
This reverts commit e810d55809.
The commit was not taken into account the fact that strduped string could be
modified. Checking if such modification happens would make the function very
costly, without a test case in mind it's not worth the effort.
It actually implements support for seeing through loads, using alias analysis to
refine the result.
This is rather limited, but I didn't want to rely on more than available
analysis at that point (to be gentle with compilation time), and it does seem to
catch common scenario, as showcased by the included tests.
Differential Revision: https://reviews.llvm.org/D122431
This lines up with other parts of the codebase that only use special
knowledge about allocator functions if they're builtins.
Differential Revision: https://reviews.llvm.org/D123053
This got changed to use hasAttrSomewhere() during review, and I didn't
notice until today when I was writing some tests for another part of
this system that using hasAttrSomewhere only checked the callsite for
allocalign, rather than both the callsite and the definition. This fixes
that by introducing a helper method.
Differential Revision: https://reviews.llvm.org/D121641
This has been true since dba73135c8, but
didn't matter until now because clang wasn't emitting allocalign
attributes.
Differential Revision: https://reviews.llvm.org/D121640
The implementation is just a generalization of the Select handler.
We're no trying to be smart and compute any kind of fixed point.
Differential Revision: https://reviews.llvm.org/D121897
Prior to this change LLVM would happily elide a call to any allocation
function and a call to any free function operating on the same unused
pointer. This can cause problems in some obscure cases, for example if
the body of operator::new can be inlined but the body of
operator::delete can't, as in this example from jyknight:
#include <stdlib.h>
#include <stdio.h>
int allocs = 0;
void *operator new(size_t n) {
allocs++;
void *mem = malloc(n);
if (!mem) abort();
return mem;
}
__attribute__((noinline)) void operator delete(void *mem) noexcept {
allocs--;
free(mem);
}
void deleteit(int*i) { delete i; }
int main() {
int*i = new int;
deleteit(i);
if (allocs != 0)
printf("MEMORY LEAK! allocs: %d\n", allocs);
}
This patch addresses the issue by introducing the concept of an
allocator function family and uses it to make sure that alloc/free
function pairs are only removed if they're in the same family.
Differential Revision: https://reviews.llvm.org/D117356
The code was using exact sizing only, but since what we really need is just to make sure the offsets are in bounds, a minimum bound on the object size is sufficient.
To demonstrate the difference, support computing minimum sizes from obects of scalable vector type.
Use existing functionality to strip constant offsets that works well
with AS casts and avoids the code duplication.
Since we strip AS casts during the computation of the offset we also
need to adjust the APInt properly to avoid mismatches in the bit width.
This code ensures the caller of `compute` sees APInts that match the
index type size of the value passed to `compute`, not the value result
of the strip pointer cast.
Fixes#53559.
Differential Revision: https://reviews.llvm.org/D118727
This is in anticipation of my next patch, where I need to store more information about free functions than just their argument count. It felt invasive enough on this function that it seemed worthwhile to just extract this as its own commit that makes no functional changes.
Differential Revision: https://reviews.llvm.org/D117350
The basic idea is that we can parameterize the getObjectSize implementation with a callback which lets us replace the operand before analysis if desired. This is what Attributor is doing during it's abstract interpretation, and allows us to have one copy of the code.
Note this is not NFC for two reasons:
* The existing attributor code is wrong. (Well, this is under-specified to be honest, but at least inconsistent.) The intermediate math needs to be done in the index type of the pointer space. Imagine e.g. i64 arguments in a 32 bit address space.
* I did not preserve the behavior in getAPInt where we return 0 for a partially analyzed value. This looks simply wrong in the original code, and nothing test wise contradicts that.
Differential Revision: https://reviews.llvm.org/D117241
Not all allocation functions are removable if unused. An example of a non-removable allocation would be a direct call to the replaceable global allocation function in C++. An example of a removable one - at least according to historical practice - would be malloc.
(Split from original patch to separate non-NFC part and add coverage. I typoed when adding the new test, so this change includes the typo fix to let libfunc recongize the signature. Didn't figure it was worth another separate commit.)
Differential Revision: https://reviews.llvm.org/D116851 (part 2 of 2)
There are a few places where the alignment argument for AlignedAllocLike functions was previously hardcoded. This patch adds an getAllocAlignment function and a change to the MemoryBuiltin table to allow alignment arguments to be found generically.
This will shortly allow alignment inference on operator new's with align_val params and an extension to Attributor's HeapToStack. The former will follow shortly - I split Bryce's patch for purpose of having the large change be NFC. The later will be reviewed separately.
Differential Revision: https://reviews.llvm.org/D116851 (part 1 of 2)
We currently have two similar implementations of this concept:
isNoAliasCall() only checks for the noalias return attribute.
isNoAliasFn() also checks for allocation functions.
We should switch to only checking the attribute. SLC is responsible
for inferring the noalias return attribute for non-new allocation
functions (with a missing case fixed in
348bc76e35).
For new, clang is responsible for setting the attribute,
if -fno-assume-sane-operator-new is not passed.
Differential Revision: https://reviews.llvm.org/D116800
strdup/strndup are already partially implemented, move remaining comment to relevant place. Remaining named routines are copy routines and mostly handled via intrinsics already - they do not allocate new memory.
This is a reoccuring pattern, we can consolidate three copies into one. The main motivation is to reduce usages of isMallocLike.
The original commit (which was quickly reverted) didn't account for the allocation function could be an invoke, test coverage for that case added in this commit.
Kazu Hirata