Add support of parsing .csky_attribute directive and emit related target attributes in .csky.attribute section.
It does not emit attribute directive in assembly code, so only emit target attributes in ELF streamer.
In ELF streamer, it handles the header EFlag and the csky_attribute section which contains some attribute items.
The EFlag and attribute items are calculated from feature bits based on Subtarget.
There are kinds of inline asm constraints and corresponding register class or register as following.
'b': mGPRRegClass
'v': sGPRRegClass
'w': sFPR32RegClass or sFPR64RegClass
'c': C register
'z': R14 register
'h': HI register
'l': LO register
'y': HI or LO register
It also adds codegen test for inline-asm including constraints, clobbers and abi names.
There are static and dynamic TLS address lowering in DAG stage according to different TLS model.
It needs PseudoTLSLA32 pseudo to get address of TLS-related entry which resides in constant pool.
Loading constants inline is expensive on CSKY and it's in general better
to place the constant nearby in code space and then it can be loaded with a
simple 16/32 bit load instruction like lrw.
It needs lift or duplicates constant pool entry to make constant nearby so that lrw instruction can reach.
Lower global symbols such as call/external symbol.
Lower other leaf DAG node such as frame address/block address/jumptable/vastart.
Normally some leaf symbols need reside in constant pool as ABI prefers, and are addressed by
lrw or jsri instructions.
Every symbol in constant pool is lowered with one entry in target constant pool. The
entry has different type corresponding to different leaf node such as blockaddress,
jumptable, or global value.
Add all CompressPat to map instructions between 16-bit and 32-bit with using the CompressInstEmitter infra.
Although it's only used in asm printer, also enable it in asm parser to debug mapping when -enable-csky-asm-compressed-inst is on.
Differential Revision: https://reviews.llvm.org/D115026
Ooops. It constructs codegen infra and provide only basic code to generate first add instruction successfully.
Differential Revision: https://reviews.llvm.org/D112206
