[RISCV][NFC] Split PseudoCALL pattern out from instruction

[jrtc27]

Summary

Since PseudoCALL defines AsmString, it can be generated from assembly,
and so code-gen patterns should be defined separately to be consistent
with the style of the RISCV backend. Other pseudo-instructions exist
that have code-gen patterns defined directly, but these instructions are
purely for code-gen and cannot be written in assembly.

[lenary]

This looks good to me!

You've got quite a few useful patches that have been approved. Please may you request commit access so you can land them? https://www.llvm.org/docs/DeveloperPolicy.html#obtaining-commit-access

llvm/trunk/lib/Target/RISCV/RISCVInstrInfo.td

 
 // PseudoCALL is a pseudo instruction which will eventually expand to auipc
 // and jalr while encoding. This is desirable, as an auipc+jalr pair with
 // R_RISCV_CALL and R_RISCV_RELAX relocations can be be relaxed by the linker
 // if the offset fits in a signed 21-bit immediate.
 // Define AsmString to print "call" when compile with -S flag.
 // Define isCodeGenOnly = 0 to support parsing assembly "call" instruction.
 let isCall = 1, Defs = [X1], isCodeGenOnly = 0 in
-def PseudoCALL : Pseudo<(outs), (ins call_symbol:$func),
-                        [(riscv_call tglobaladdr:$func)]> {
+def PseudoCALL : Pseudo<(outs), (ins call_symbol:$func), []> {
   let AsmString = "call\t$func";
 }
 
+def : Pat<(riscv_call tglobaladdr:$func), (PseudoCALL tglobaladdr:$func)>;
 def : Pat<(riscv_call texternalsym:$func), (PseudoCALL texternalsym:$func)>;
 
 def : Pat<(riscv_uret_flag), (URET X0, X0)>;
 def : Pat<(riscv_sret_flag), (SRET X0, X0)>;
 def : Pat<(riscv_mret_flag), (MRET X0, X0)>;
 
 let isCall = 1, Defs = [X1] in
 def PseudoCALLIndirect : Pseudo<(outs), (ins GPR:$rs1),