Generate nuw GEPs for struct member accesses, as inbounds + non-negative
implies nuw.

Regression tests are updated using update scripts where possible, and by
find + replace where not.

While lowering (#pragma omp target update from), clang's generated
.omp_task_entry. is setting up 9 arguments while calling
__tgt_target_data_update_nowait_mapper.

At the same time, in __tgt_target_data_update_nowait_mapper, call to
targetData<TaskAsyncInfoWrapperTy>() is converted to a sibcall assuming
it has the argument count listed in the signature.

AARCH64 asm sequence for this is as follows (removed unrelated insns):

`
.omp_task_entry..108:
  sub   sp, sp, #32
  stp   x29, x30, sp, #16       // 16-byte Folded Spill
  add   x29, sp, #16
  str   x8, sp, #8. // stack canary
  str   xzr, [sp]
  bl   __tgt_target_data_update_nowait_mapper

__tgt_target_data_update_nowait_mapper:
  sub   sp, sp, #32
  stp   x29, x30, sp, #16       // 16-byte Folded Spill
  add   x29, sp, #16
  str   x8, sp, #8 // stack canary
  // Sibcall argument setup
adrp x8,
:got:_Z16targetDataUpdateP7ident_tR8DeviceTyiPPvS4_PlS5_S4_S4_R11AsyncInfoTyb
ldr x8, [x8,
:got_lo12:_Z16targetDataUpdateP7ident_tR8DeviceTyiPPvS4_PlS5_S4_S4_R11AsyncInfoTyb]
  stp   x9, x8, x29, #16
  adrp  x8, .L.str.8
  add   x8, x8, :lo12:.L.str.8
  str   x8, x29, #32. <==. This is the insn that erases $fp

  ldp   x29, x30, sp, #16       // 16-byte Folded Reload
  add   sp, sp, #32
  // Sibcall
b
ZL10targetDataI22TaskAsyncInfoWrapperTyEvP7ident_tliPPvS4_PlS5_S4_S4_PFiS2_R8DeviceTyiS4_S4_S5_S5_S4_S4_R11AsyncInfoTybEPKcSD
`

On AArch64, call to __tgt_target_data_update_nowait_mapper in
.omp_task_entry. sets up only single space on stack and this results in
ovewriting $fp and subsequent stack corruption. This issue can be
credited to discrepancy of __tgt_target_data_update_nowait_mapper
signature in openmp/libomptarget/include/omptarget.h taking 13 arguments
while clang/lib/CodeGen/CGOpenMPRuntime.cpp and
llvm/include/llvm/Frontend/OpenMP/OMPKinds.def taking only 9 arguments.

This patch modifies __tgt_target_data_update_nowait_mapper signature to
match .omp_task_entry usage(and other 2 files mentioned above).

Co-authored-by: Kugan Vivekanandarajah <kvivekananda@nvidia.com>

Reapplication of 7339c0f782d5c70e0928f8991b0c05338a90c84c with a fix
for a crash involving arrays without a size expression.

Clang supports VLAs in C++ as an extension, but we currently only warn
on their use when you pass -Wvla, -Wvla-extension, or -pedantic.
However, VLAs as they're expressed in C have been considered by WG21
and rejected, are easy to use accidentally to the surprise of users
(e.g., https://ddanilov.me/default-non-standard-features/), and they
have potential security implications beyond constant-size arrays
(https://wiki.sei.cmu.edu/confluence/display/c/ARR32-C.+Ensure+size+arguments+for+variable+length+arrays+are+in+a+valid+range).
C++ users should strongly consider using other functionality such as
std::vector instead.

This seems like sufficiently compelling evidence to warn users about
VLA use by default in C++ modes. This patch enables the -Wvla-extension
diagnostic group in C++ language modes by default, and adds the warning
group to -Wall in GNU++ language modes. The warning is still opt-in in
C language modes, where support for VLAs is somewhat less surprising to
users.

RFC: https://discourse.llvm.org/t/rfc-diagnosing-use-of-vlas-in-c/73109
Fixes https://github.com/llvm/llvm-project/issues/62836
Differential Revision: https://reviews.llvm.org/D156565

This reverts commit 7339c0f782d5c70e0928f8991b0c05338a90c84c.

Breaks bots:
https://lab.llvm.org/buildbot/#/builders/139/builds/51875
https://lab.llvm.org/buildbot/#/builders/164/builds/45262

Clang supports VLAs in C++ as an extension, but we currently only warn
on their use when you pass -Wvla, -Wvla-extension, or -pedantic.
However, VLAs as they're expressed in C have been considered by WG21
and rejected, are easy to use accidentally to the surprise of users
(e.g., https://ddanilov.me/default-non-standard-features/), and they
have potential security implications beyond constant-size arrays
(https://wiki.sei.cmu.edu/confluence/display/c/ARR32-C.+Ensure+size+arguments+for+variable+length+arrays+are+in+a+valid+range).
C++ users should strongly consider using other functionality such as
std::vector instead.

This seems like sufficiently compelling evidence to warn users about
VLA use by default in C++ modes. This patch enables the -Wvla-extension
diagnostic group in C++ language modes by default, and adds the warning
group to -Wall in GNU++ language modes. The warning is still opt-in in
C language modes, where support for VLAs is somewhat less surprising to
users.

RFC: https://discourse.llvm.org/t/rfc-diagnosing-use-of-vlas-in-c/73109
Fixes https://github.com/llvm/llvm-project/issues/62836
Differential Revision: https://reviews.llvm.org/D156565

Reviewed By: nikic

Differential Revision: https://reviews.llvm.org/D150733

This removes creation of udiv/sdiv/urem/srem constant expressions,
in preparation for their removal. I've added a
ConstantExpr::isDesirableBinOp() predicate to determine whether
an expression should be created for a certain operator.

With this patch, div/rem expressions can still be created through
explicit IR/bitcode, forbidding them entirely will be the next step.

Differential Revision: https://reviews.llvm.org/D128820

This adds -no-opaque-pointers to clang tests whose output will
change when opaque pointers are enabled by default. This is
intended to be part of the migration approach described in
https://discourse.llvm.org/t/enabling-opaque-pointers-by-default/61322/9.

The patch has been produced by replacing %clang_cc1 with
%clang_cc1 -no-opaque-pointers for tests that fail with opaque
pointers enabled. Worth noting that this doesn't cover all tests,
there's a remaining ~40 tests not using %clang_cc1 that will need
a followup change.

Differential Revision: https://reviews.llvm.org/D123115

Changed the we handle llvm::Constants in sizes arrays. ConstExprs and
GlobalValues cannot be used as initializers, need to put them at the
runtime, otherwise there wight be the compilation errors.

Differential Revision: https://reviews.llvm.org/D105297

This reverts commit 638938117aeae5518d6cacd066ffd9830ef4fc9a. Need to
fix reported fail https://lab.llvm.org/buildbot/#/builders/193/builds/7496