Changes

[MLIR][OpenMP] Removed the ambiguity in flush op assembly syntax

Summary:
========
Bugzilla Ticket No: Bug 46884 [https://bugs.llvm.org/show_bug.cgi?id=46884]

Flush op assembly syntax was ambiguous:

Consider the below test case:
flush operation is not having any arguments.
But the next statement token i.e "%2" is read as the argument for flush operation and then translator issues an error.
***************************************************************
$ cat -n flush.mlir
     1  llvm.func @_QQmain(%arg0: !llvm.i32) {
     2    %0 = llvm.mlir.constant(1 : i64) : !llvm.i64
     3    %1 = llvm.alloca %0 x !llvm.i32 {in_type = i32, name = "a"} : (!llvm.i64) -> !llvm.ptr<i32>
     4    omp.flush
     5    %2 = llvm.load %1 : !llvm.ptr<i32>
     6    llvm.return
     7  }

$ mlir-translate -mlir-to-llvmir flush.mlir
flush.mlir:5:6: error: expected ':'
  %2 = llvm.load %1 : !llvm.ptr<i32>
     ^
***************************************************************

Solution:
=========
Introduced begin ( `(` ) and end token ( `)` ) to determince the begin and end of variadic arguments.

The patch includes code changes and testcase modifications.

Reviewed By: Valentin Clement, Mehdi AMINI

Differential Revision: https://reviews.llvm.org/D88376

[OpenMP][FIX] Verify compatible types for declare variant calls

Especially for templates we need to check at some point if the base
function matches the specialization we might call instead. Before this
lead to the replacement of `std::sqrt(int(2))` calls with one that
converts the argument to a `std::complex<int>`, clearly not the desired
behavior.

Reported as PR47655

Reviewed By: JonChesterfield

Differential Revision: https://reviews.llvm.org/D88384

[IndVars] Remove exiting conditions that are trivially true/false

When removing exiting loop conditions, we only consider checks for
which we know the exact exit count. We could also eliminate checks for
which the condition is always true/false.

Differential Revision: https://reviews.llvm.org/D87344
Reviewed By: lebedev.ri, reames

[NFC] Use assert instead of checking the guaranteed condition

From preconditions it is known that either A dominates B or
B dominates A. If A does not dominate B, we do not really need
to check it. Assert should be enough. Should save some compile
time.

[Docs][NewPM] Add note about required passes

Reviewed By: ychen

Differential Revision: https://reviews.llvm.org/D88342

Revert "[OpenMP][FIX] Verify compatible types for declare variant calls"

This reverts commit c942095790decf525a445f3bd68fb9bcc9aa43c6.

One of the tests broke, revert to investigate.

[X86] Add known bits test for PEXT. NFC

[X86] Add computeKnownBits support for PEXT.

The number of zeros in the mask provides a lower bound on the number
of leading zeros in the result.

[Driver] Filter out <libdir>/gcc and <libdir>/gcc-cross if they do not exists

Differential Revision: https://reviews.llvm.org/D87901

This reduces code duplication between CGObjCMac.cpp and Mangle.cpp
for generating the mangled name of an Objective-C method.

This has no intended functionality change.

https://reviews.llvm.org/D88329