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evaluation.
llvm-svn: 360559
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their lifetime in constant expressions.
This is undefined behavior per [class.cdtor]p2.
We continue to allow this for objects whose values are not visible
within the constant evaluation, because there's no way we can tell
whether the access is defined or not, existing code relies on the
ability to make such calls, and every other compiler allows such
calls.
This reinstates r360499, reverted in r360531.
llvm-svn: 360538
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evaluation.
It's not enough to just track the LValueBase that we're evaluating, we
need to also track the path to the objects whose constructors are
running.
This reinstates r360464 (reverted in r360531) with a workaround for an
MSVC bug that previously caused the Windows bots to fail.
llvm-svn: 360537
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Reject attempts to call non-static member functions on objects outside
their lifetime in constant expressions.
This is undefined behavior per [class.cdtor]p2.
We continue to allow this for objects whose values are not visible
within the constant evaluation, because there's no way we can tell
whether the access is defined or not, existing code relies on the
ability to make such calls, and every other compiler allows such
calls.
........
Fix handling of objects under construction during constant expression
evaluation.
It's not enough to just track the LValueBase that we're evaluating, we
need to also track the path to the objects whose constructors are
running.
........
Fixes windows buildbots
llvm-svn: 360531
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their lifetime in constant expressions.
This is undefined behavior per [class.cdtor]p2.
We continue to allow this for objects whose values are not visible
within the constant evaluation, because there's no way we can tell
whether the access is defined or not, existing code relies on the
ability to make such calls, and every other compiler allows such
calls.
llvm-svn: 360499
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evaluation.
It's not enough to just track the LValueBase that we're evaluating, we
need to also track the path to the objects whose constructors are
running.
llvm-svn: 360464
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llvm-svn: 360463
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llvm-svn: 360408
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evaluation.
Not even in cases where we would not actually perform virtual dispatch.
llvm-svn: 360370
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state when it's encountered while evaluating a constexpr function.
We attempt to follow GCC trunk's behavior here, but it is somewhat
inscrutible, so our behavior is only approximately the same for now.
Specifically, we only permit modification of objects whose lifetime
began within the operand of the __builtin_constant_p. GCC appears to
have effectively the same restriction, but also some unknown restriction
based on where and how the local state of the constexpr function is
mentioned within the operand (see added testcases).
llvm-svn: 359958
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llvm-svn: 359913
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__builtin_constant_p.
If the operand of __builtin_constant_p is not constant and has
side-effects, then code controlled by a branch on it is unreachable and
we should not emit runtime behavior warnings in such code.
llvm-svn: 359844
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us emitting the operand of __builtin_constant_p if it has side-effects.
Original commit message:
Fix interactions between __builtin_constant_p and constexpr to match
current trunk GCC.
GCC permits information from outside the operand of
__builtin_constant_p (but in the same constant evaluation context) to be
used within that operand; clang now does so too. A few other minor
deviations from GCC's behavior showed up in my testing and are also
fixed (matching GCC):
* Clang now supports nullptr_t as the argument type for
__builtin_constant_p
* Clang now returns true from __builtin_constant_p if called with a
null pointer
* Clang now returns true from __builtin_constant_p if called with an
integer cast to pointer type
llvm-svn: 359367
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current trunk GCC.
This reverts r359059 (git commit 0b098754b73f3b96d00ecb1c7605760b11c90298)
llvm-svn: 359361
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Summary:
This patch implements `__builtin_is_constant_evaluated` as specifier by [P0595R2](https://wg21.link/p0595r2). It is built on the back of Bill Wendling's work for `__builtin_constant_p()`.
More tests to come, but early feedback is appreciated.
I plan to implement warnings for common mis-usages like those belowe in a following patch:
```
void foo(int x) {
if constexpr (std::is_constant_evaluated())) { // condition is always `true`. Should use plain `if` instead.
foo_constexpr(x);
} else {
foo_runtime(x);
}
}
```
Reviewers: rsmith, MaskRay, bruno, void
Reviewed By: rsmith
Subscribers: dexonsmith, zoecarver, fdeazeve, kristina, cfe-commits
Differential Revision: https://reviews.llvm.org/D55500
llvm-svn: 359067
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current trunk GCC.
GCC permits information from outside the operand of
__builtin_constant_p (but in the same constant evaluation context) to be
used within that operand; clang now does so too. A few other minor
deviations from GCC's behavior showed up in my testing and are also
fixed (matching GCC):
* Clang now supports nullptr_t as the argument type for
__builtin_constant_p
* Clang now returns true from __builtin_constant_p if called with a
null pointer
* Clang now returns true from __builtin_constant_p if called with an
integer cast to pointer type
llvm-svn: 359059
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arguments, enumerators, case statements, and the enable_if attribute.
Summary:
The following code is accepted by Clang 7 and prior but rejected by the upcoming 8 release and in trunk [1]
```
// error {{never produces a constant expression}}
void foo(const char* s) __attribute__((enable_if(__builtin_constant_p(*s) == false, "trap"))) {}
void test() { foo("abc"); }
```
Prior to Clang 8, the call to `__builtin_constant_p` was a constant expression returning false. Currently, it's not a valid constant expression.
The bug is caused because we failed to set `InConstantContext` when attempting to evaluate unevaluated constant expressions.
[1] https://godbolt.org/z/ksAjmq
Reviewers: rsmith, hans, sbenza
Reviewed By: rsmith
Subscribers: kristina, cfe-commits
Tags: #clang
Differential Revision: https://reviews.llvm.org/D59038
llvm-svn: 355743
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expression inside the parentheses is a valid UTF-8 string literal.
Previously clang emitted an expression like @("abc") as a message send
to stringWithUTF8String. This commit makes clang emit the boxed
expression as a compile-time constant instead.
This commit also has the effect of silencing the nullable-to-nonnull
conversion warning clang started emitting after r317727, which
originally motivated this commit (see https://oleb.net/2018/@keypath).
rdar://problem/42684601
Differential Revision: https://reviews.llvm.org/D58729
llvm-svn: 355662
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Apparently GCC allows this, and there's code relying on it (see bug).
The idea is to allow expression that would have been allowed if they
were cast to int. So I based the code on how such a cast would be done
(the CK_PointerToIntegral case in IntExprEvaluator::VisitCastExpr()).
Differential Revision: https://reviews.llvm.org/D58821
llvm-svn: 355491
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This patch includes the necessary code for converting between a fixed point type and integer.
This also includes constant expression evaluation for conversions with these types.
Differential Revision: https://reviews.llvm.org/D56900
llvm-svn: 355462
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This patch implements fixed point comparisons with other fixed point types and
integers. This also provides constant expression evaluation for them.
Differential Revision: https://reviews.llvm.org/D57219
llvm-svn: 354621
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Summary:
This makes it consistent with `memcmp` and `__builtin_bcmp`.
Also see the discussion in https://reviews.llvm.org/D56593.
Reviewers: jyknight
Subscribers: kristina, cfe-commits
Tags: #clang
Differential Revision: https://reviews.llvm.org/D58120
llvm-svn: 354023
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I assumed lvalue-to-rvalue conversions of array type would never
happen, but apparently clang-tidy tries in some cases.
llvm-svn: 353598
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This allows substantially simplifying the expression evaluation code,
because we don't have to special-case lvalues which are actually string
literal initialization.
This currently throws away an optimization where we would avoid creating
an array APValue for string literal initialization. If we really want
to optimize this case, we should fix APValue so it can store simple
arrays more efficiently, like llvm::ConstantDataArray. This shouldn't
affect the memory usage for other string literals. (Not sure if this is
a blocker; I don't think string literal init is common enough for this
to be a serious issue, but I could be wrong.)
The change to test/CodeGenObjC/encode-test.m is a weird side-effect of
these changes: we currently don't constant-evaluate arrays in C, so the
strlen call shouldn't be folded, but lvalue string init managed to get
around that check. I this this is fine.
Fixes https://bugs.llvm.org/show_bug.cgi?id=40430 .
llvm-svn: 353569
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This builtin has the same UI as __builtin_object_size, but has the
potential to be evaluated dynamically. It is meant to be used as a
drop-in replacement for libraries that use __builtin_object_size when
a dynamic checking mode is enabled. For instance,
__builtin_object_size fails to provide any extra checking in the
following function:
void f(size_t alloc) {
char* p = malloc(alloc);
strcpy(p, "foobar"); // expands to __builtin___strcpy_chk(p, "foobar", __builtin_object_size(p, 0))
}
This is an overflow if alloc < 7, but because LLVM can't fold the
object size intrinsic statically, it folds __builtin_object_size to
-1. With __builtin_dynamic_object_size, alloc is passed through to
__builtin___strcpy_chk.
rdar://32212419
Differential revision: https://reviews.llvm.org/D56760
llvm-svn: 352665
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to reflect the new license.
We understand that people may be surprised that we're moving the header
entirely to discuss the new license. We checked this carefully with the
Foundation's lawyer and we believe this is the correct approach.
Essentially, all code in the project is now made available by the LLVM
project under our new license, so you will see that the license headers
include that license only. Some of our contributors have contributed
code under our old license, and accordingly, we have retained a copy of
our old license notice in the top-level files in each project and
repository.
llvm-svn: 351636
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This patch includes logic for constant expression evaluation of fixed point additions.
Differential Revision: https://reviews.llvm.org/D55868
llvm-svn: 351593
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This adds APFixedPoint to the union of values that can be represented with an APValue.
Differential Revision: https://reviews.llvm.org/D56746
llvm-svn: 351368
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Summary:
https://reviews.llvm.org/D54862 removed the usages of `ASTContext&` from
within the `CXXMethodDecl::getThisType` method. Remove the parameter
altogether, as well as all usages of it. This does not result in any
functional change because the parameter was unused since
https://reviews.llvm.org/D54862.
Test Plan: check-clang
Reviewers: akyrtzi, mikael
Reviewed By: mikael
Subscribers: mehdi_amini, dexonsmith, cfe-commits
Differential Revision: https://reviews.llvm.org/D56509
llvm-svn: 350914
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has floating point type
Fixes PR39858
Differential Revision: https://reviews.llvm.org/D55413
llvm-svn: 349444
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Summary:
This patch adds `__builtin_launder`, which is required to implement `std::launder`. Additionally GCC provides `__builtin_launder`, so thing brings Clang in-line with GCC.
I'm not exactly sure what magic `__builtin_launder` requires, but based on previous discussions this patch applies a `@llvm.invariant.group.barrier`. As noted in previous discussions, this may not be enough to correctly handle vtables.
Reviewers: rnk, majnemer, rsmith
Reviewed By: rsmith
Subscribers: kristina, Romain-Geissler-1A, erichkeane, amharc, jroelofs, cfe-commits, Prazek
Differential Revision: https://reviews.llvm.org/D40218
llvm-svn: 349195
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types
Summary:
`memchr` and `memcmp` operate upon the character units of the object
representation; that is, the `size_t` parameter expresses the number of
character units. The constant folding implementation is updated in this
patch to account for multibyte element types in the arrays passed to
`memchr`/`memcmp` and, in the case of `memcmp`, to account for the
possibility that the arrays may have differing element types (even when
they are byte-sized).
Actual inspection of the object representation is not implemented.
Comparisons are done only between elements with the same object size;
that is, `memchr` will fail when inspecting at least one character unit
of a multibyte element. The integer types are assumed to have two's
complement representation with 0 for `false`, 1 for `true`, and no
padding bits.
`memcmp` on multibyte elements will only be able to fold in cases where
enough elements are equal for the answer to be 0.
Various tests are added to guard against incorrect folding for cases
that miscompile on some system or other prior to this patch. At the same
time, the unsigned 32-bit `wchar_t` testing in
`test/SemaCXX/constexpr-string.cpp` is restored.
Reviewers: rsmith, aaron.ballman, hfinkel
Reviewed By: rsmith
Subscribers: cfe-commits
Differential Revision: https://reviews.llvm.org/D55510
llvm-svn: 348938
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Implement support for try-catch blocks in constexpr functions, as
proposed in http://wg21.link/P1002 and voted in San Diego for c++20.
The idea is that we can still never throw inside constexpr, so the catch
block is never entered. A try-catch block like this:
try { f(); } catch (...) { }
is then morally equivalent to just
{ f(); }
Same idea should apply for function/constructor try blocks.
rdar://problem/45530773
Differential Revision: https://reviews.llvm.org/D55097
llvm-svn: 348789
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Summary: Found via `codespell -q 3 -I ../clang-whitelist.txt -L uint,importd,crasher,gonna,cant,ue,ons,orign,ned`
Reviewers: teemperor
Reviewed By: teemperor
Subscribers: teemperor, jholewinski, jvesely, nhaehnle, whisperity, jfb, cfe-commits
Differential Revision: https://reviews.llvm.org/D55475
llvm-svn: 348755
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The constant emitter may need to evaluate the expression in a constant context.
For exasmple, global initializer lists.
llvm-svn: 348070
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It seems the two failing tests can be simply fixed after r348037
Fix 3 cases in Analysis/builtin-functions.cpp
Delete the bad CodeGen/builtin-constant-p.c for now
llvm-svn: 348053
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Kept the "indirect_builtin_constant_p" test case in test/SemaCXX/constant-expression-cxx1y.cpp
while we are investigating why the following snippet fails:
extern char extern_var;
struct { int a; } a = {__builtin_constant_p(extern_var)};
llvm-svn: 348039
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Summary:
Reinstate the original behavior (Success(false, E)) before D54355 when this branch is
taken. This fixes spurious error of the following snippet:
extern char extern_var;
struct { int a; } a = {__builtin_constant_p(extern_var)};
llvm-svn: 348037
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This was reverted in r347656 due to me thinking it caused a miscompile of
Chromium. Turns out it was the Chromium code that was broken.
llvm-svn: 347756
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This caused a miscompile in Chrome (see crbug.com/908372) that's
illustrated by this small reduction:
static bool f(int *a, int *b) {
return !__builtin_constant_p(b - a) || (!(b - a));
}
int arr[] = {1,2,3};
bool g() {
return f(arr, arr + 3);
}
$ clang -O2 -S -emit-llvm a.cc -o -
g() should return true, but after r347417 it became false for some reason.
This also reverts the follow-up commits.
r347417:
> Re-Reinstate 347294 with a fix for the failures.
>
> Don't try to emit a scalar expression for a non-scalar argument to
> __builtin_constant_p().
>
> Third time's a charm!
r347446:
> The result of is.constant() is unsigned.
r347480:
> A __builtin_constant_p() returns 0 with a function type.
r347512:
> isEvaluatable() implies a constant context.
>
> Assume that we're in a constant context if we're asking if the expression can
> be compiled into a constant initializer. This fixes the issue where a
> __builtin_constant_p() in a compound literal was diagnosed as not being
> constant, even though it's always possible to convert the builtin into a
> constant.
r347531:
> A "constexpr" is evaluated in a constant context. Make sure this is reflected
> if a __builtin_constant_p() is a part of a constexpr.
llvm-svn: 347656
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if a __builtin_constant_p() is a part of a constexpr.
llvm-svn: 347531
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Assume that we're in a constant context if we're asking if the expression can
be compiled into a constant initializer. This fixes the issue where a
__builtin_constant_p() in a compound literal was diagnosed as not being
constant, even though it's always possible to convert the builtin into a
constant.
llvm-svn: 347512
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Don't try to emit a scalar expression for a non-scalar argument to
__builtin_constant_p().
Third time's a charm!
llvm-svn: 347417
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llvm-svn: 347389
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EvaluateAsInt() is sometimes called in a constant context. When that's the
case, we need to specify it as so.
llvm-svn: 347364
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llvm-svn: 347314
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Summary:
A __builtin_constant_p may end up with a constant after inlining. Use
the is.constant intrinsic if it's a variable that's in a context where
it may resolve to a constant, e.g., an argument to a function after
inlining.
Reviewers: rsmith, shafik
Subscribers: jfb, kristina, cfe-commits, nickdesaulniers, jyknight
Differential Revision: https://reviews.llvm.org/D54355
llvm-svn: 347294
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in constant evaluation, not just odd values.
llvm-svn: 346699
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Summary:
Compound literals, enums, file-scoped arrays, etc. require their
initializers and size specifiers to be constant. Wrap the initializer
expressions in a ConstantExpr so that we can easily check for this later
on.
Reviewers: rsmith, shafik
Reviewed By: rsmith
Subscribers: cfe-commits, jyknight, nickdesaulniers
Differential Revision: https://reviews.llvm.org/D53921
llvm-svn: 346455
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Summary:
Documentation can be found at https://www.khronos.org/registry/OpenCL/extensions/intel/cl_intel_device_side_avc_motion_estimation.txt
Patch by Kristina Bessonova
Reviewers: Anastasia, yaxunl, shafik
Reviewed By: Anastasia
Subscribers: arphaman, sidorovd, AlexeySotkin, krisb, bader, asavonic, cfe-commits
Differential Revision: https://reviews.llvm.org/D51484
llvm-svn: 346392
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