Changes

[OpenMP][OMPIRBuilder] Introducing the `OMPBuilderCBHelpers` helper class

This patch introduces a new helper class `OMPBuilderCBHelpers`,
which will contain all reusable C/C++ language specific function-
alities required by the `OMPIRBuilder`.

Initially, this helper class contains the body and finalization
codegen functionalities implemented using callbacks which were
moved here for reusability among the different directives
implemented in the `OMPIRBuilder`, along with RAIIs for preserving
state prior to emitting outlined and/or inlined OpenMP regions.

In the future this helper class will also contain all the different
call backs required by OpenMP clauses/variable privatization.

Reviewed By: jdoerfert

Differential Revision: https://reviews.llvm.org/D74562

[Hexagon] Change HVX vector predicate types from v512/1024i1 to v64/128i1

This commit removes the artificial types <512 x i1> and <1024 x i1>
from HVX intrinsics, and makes v512i1 and v1024i1 no longer legal on
Hexagon.

It may cause existing bitcode files to become invalid.

* Converting between vector predicates and vector registers must be
  done explicitly via vandvrt/vandqrt instructions (their intrinsics),
  i.e. (for 64-byte mode):
    %Q = call <64 x i1> @llvm.hexagon.V6.vandvrt(<16 x i32> %V, i32 -1)
    %V = call <16 x i32> @llvm.hexagon.V6.vandqrt(<64 x i1> %Q, i32 -1)

  The conversion intrinsics are:
    declare  <64 x i1> @llvm.hexagon.V6.vandvrt(<16 x i32>, i32)
    declare <128 x i1> @llvm.hexagon.V6.vandvrt.128B(<32 x i32>, i32)
    declare <16 x i32> @llvm.hexagon.V6.vandqrt(<64 x i1>, i32)
    declare <32 x i32> @llvm.hexagon.V6.vandqrt.128B(<128 x i1>, i32)
  They are all pure.

* Vector predicate values cannot be loaded/stored directly. This directly
  reflects the architecture restriction. Loading and storing or vector
  predicates must be done indirectly via vector registers and explicit
  conversions via vandvrt/vandqrt instructions.

[x86] add test for uint->fp with unsafe-fp-math (PR43609); NFC

[AMDGPU] Update AMDGPUUsage with DWARF proposal

Summary:
- Add AMDGPU DWARF proposal.
- Add references for gfx10 ISA and SemVer.

Subscribers: kzhuravl, jvesely, wdng, nhaehnle, yaxunl, aprantl, dstuttard, tpr, jfb, dmgreen, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D70523

[IndVarSimply] Fix assert/release build difference.

In builds with assertions enabled (!NDEBUG), IndVarSimplify does an
additional query to ScalarEvolution which may change future SCEV queries
since it fills the internal cache differently. The result is actually
only used with the -verify-indvars command line option. We fix the issue
by only calling SE->getBackedgeTakenCount(L) if -verify-indvars is
enabled such that only -verify-indvars shows the behavior, but not debug
builds themselves. Also add a remark to the description of
-verify-indvars about this behavior.

Fixes llvm.org/PR44815

Differential Revision: https://reviews.llvm.org/D74810

[AMDGPU] AMDGPUUsage define call convention ABI

Reviewers: scott.linder, arsenm, b-sumner

Subscribers: kzhuravl, jvesely, wdng, nhaehnle, yaxunl, dstuttard, tpr, kerbowa, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D74861

[libc++] Fixes backreferences for extended grammar.

The regex backreferences were not properly parsed and used when using
the extended grammar. This change parses them. The issue was found while
working on PR34297.

Thanks to Mark de Wever for the patch!

Differential Revision: https://reviews.llvm.org/D62451

[libc++] reduce <complex> parsing time

Instead of including <ios> for ios_base::failbit, simply get failbit
member of the template argument. Print directly to a stream instead
of using intermediate ostringstream.

    Parsing time: 874ms -> 164ms (-81%)

Thanks to Nikita Kniazev for the patch!

Differential Revision: https://reviews.llvm.org/D71214