[clang] [llvm] [Clang][OpenMP] Support for dispatch construct (Sema & Codegen) support (PR #131838)

[Alexey Bataev via llvm-commits]

alexey-bataev wrote:

> > The codegen for each(virtual) directive should live on codegen. But(!) Sema should emit separate (specific) CapturedStmts for each such virtual region. Check, how the combined directives work. Sema defines multiple CapturedStmt for each combined directive, and then codegen emits the code for each(virtual) standalone directive, using CapturedStmt for this particular (virtual) standalone directive. The list of captures of each sub-directives might be different, so Sema should provide different CapturedStmt for each emitted sub-directive.
> 
> With the present checkin the -ast-dump looks as follows:
> 
> ```
>      |-CompoundStmt 0x17f4a10 <<invalid sloc>>
>      |  |-OMPTaskwaitDirective 0x1838208 <line:29:5, col:54> openmp_standalone_directive
>      |  |  `-OMPDependClause 0x1837dc0 <col:40, col:53>
>      |  |   `-DeclRefExpr 0x1837d88 <col:52> 'int' lvalue Var 0x1837890 'x' 'int'
>      |  `-OMPDispatchDirective 0x17f49c0 <col:5, col:54>
>      |    |-OMPNocontextClause 0x1837d60 <col:26, col:38>
>      |    |  `-ImplicitCastExpr 0x1837d30 <col:36> 'int' <LValueToRValue>
>      |    |    `-DeclRefExpr 0x1837d10 <col:36> 'int' lvalue OMPCapturedExpr 0x1837c90 '.capture_expr.' 'int'
>      |    |-OMPDependClause 0x1837dc0 <col:40, col:53>
>      |    |       `-DeclRefExpr 0x1837d88 <col:52> 'int' lvalue Var 0x1837890 'x' 'int'
>      |    `-CapturedStmt 0x18381c8 <line:30:5, col:11>
>      |        |-CapturedDecl 0x1837ef8 <<invalid sloc>> <invalid sloc>
> ```
> 
> Since, there is no need for a CapturedStmt below OMPTaskDirective none has been added. This is being processed properly and -emit-llvm produces the correct output. Can you please review the code?

There should not be taskwait directive in AST, it should be emitted in codegen. Only corresponding CapturedStmt should be built in Sema

https://github.com/llvm/llvm-project/pull/131838