This PR emits implements the ability to emit the PPC version for both
assembly and object files on AIX.

Summary:
in the function PPCFunctionInfo::getParmsType(), there is if (Bits > 31 || (Bits > 30 && (Elt != FixedType || hasVectorParms())))

when the Bit is 31 and the Elt is not FixedType(for example the Elt is FloatingType) , the 31th bit will be not encoded, it leave the bit as zero, when the function Expected<SmallString<32>> XCOFF::parseParmsType() the original implement
**// unsigned ParmsNum = FixedParmsNum + FloatingParmsNum;

while (Bits < 32 && ParsedNum < ParmsNum) {
...
}//**
it will look the 31 bits (zero) as FixedType. which should be FloatingType,  and get a error.

Reviewers: Jason Liu,ZarkoCA

Differential Revision: https://reviews.llvm.org/D105023

Summary:

emit vector info of traceback table.

Reviewers: Jason Liu,Hubert Tong
Differential Revision: https://reviews.llvm.org/D93659

SUMMARY:

In order for the runtime on AIX to find the compact unwind section(EHInfo table),
we would need to set the following on the traceback table:

The 6th byte's longtbtable field to true to signal there is an Extended TB Table Flag.
The Extended TB Table Flag to be 0x08 to signal there is an exception handling info presents.
Emit the offset between ehinfo TC entry and TOC base after all other optional portions of traceback table.

The patch is authored by Jason Liu.

Reviewers: David Tenty, Digger Lin
Differential Revision: https://reviews.llvm.org/D92766

SUMMARY:
 1. added a new option -xcoff-traceback-table to control whether generate traceback table for function.
 2. implement the functionality of emit traceback table of a function.

Reviewers: hubert.reinterpretcast, Jason Liu
Differential Revision: https://reviews.llvm.org/D92398

Move StringRef.h include to XCOFF.cpp

SUMMARY:

For the llvm-objdump -D, the symbol name is used as a label in the disassembly for the specific address (when a symbol address is equal to the virtual address in the dump).

In XCOFF, multiple symbols may have the same name, being differentiated by their storage mapping class. It is helpful to print the QualName and not just the name when forming the output label for a csect symbol. The symbol index further removes any ambiguity caused by duplicate names.

To maintain compatibility with the binutils objdump, the XCOFF-specific --symbol-description option is added to enable the enhanced format.

Reviewers: hubert.reinterpretcast, James Henderson, Jason Liu ,daltenty
Subscribers: wuzish, nemanjai, hiraditya

Differential Revision: https://reviews.llvm.org/D72973

Summary:
Implement several XCOFF hooks to get '-r' option working for llvm-objdump -r.

Reviewer: DiggerLin, hubert.reinterpretcast, jhenderson, MaskRay

Differential Revision: https://reviews.llvm.org/D75131

Summary:
Emit the correct .toc psuedo op when we change to the TOC and emit
TC entries. Make sure TOC psuedos get the right symbols via overriding
getMCSymbolForTOCPseudoMO on AIX. Add a test for TOC assembly writing
and update tests to include TOC entries.

Also make sure external globals have a csect set and handle external function descriptor (originally authored by Jason Liu) so we can emit TOC entries for them.

Reviewers: DiggerLin, sfertile, Xiangling_L, jasonliu, hubert.reinterpretcast

Reviewed By: jasonliu

Subscribers: arphaman, wuzish, nemanjai, hiraditya, kbarton, jsji, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D70461

SUMMARY:
The patch will emit read-only variable assembly code for aix.

Reviewers: daltenty,Xiangling_Liao
Subscribers: rupprecht, seiyai,hiraditya

Differential Revision: https://reviews.llvm.org/D70182