Refine the condition for when to use CALL16 vs a GOT displacement.

[bsdjhb]

Summary

Borrow from the logic for 'jal' in MipsAsmParser::processInstruction
and add the extra condition of bypassing CALL16 if the destination symbol
is an ELF symbol with STB_LOCAL binding.

[bsdjhb]

Splitting this out from D33948. However, I'm also interested in the patch you mentioned in the other review for fixing forward-declared local symbols. It may be that fixing that resolves the use case that prompted this patch, so I'm not sure if checking STB_LOCAL will still be required.

[sdardis]

LGTM apart from formatting. Do you need me to commit this for you?

lib/Target/Mips/AsmParser/MipsAsmParser.cpp

2868–2872 ↗

(On Diff #101761)

This hunk is not clang-formatted. It should be:

if ((DstReg == Mips::T9 || DstReg == Mips::T9_64) && !UseSrcReg &&                                                 
    Res.getConstant() == 0 &&
    !(Res.getSymA()->getSymbol().isInSection() ||                                                                  
      Res.getSymA()->getSymbol().isTemporary() ||                                                                  
      (Res.getSymA()->getSymbol().isELF() &&
       cast<MCSymbolELF>(Res.getSymA()->getSymbol()).getBinding() ==                                               
           ELF::STB_LOCAL))) {

[bsdjhb]

Please commit for me as I don't have that ability currently. I'll be sure to run clang-format over my other mips64 dla PIC change and update it as well.

llvm/trunk/lib/Target/Mips/AsmParser/MipsAsmParser.cpp

if (Res.getSymB() != nullptr) {
       Error(IDLoc, "expected relocatable expression with only one symbol");
       return true;
     }
 
     // The case where the result register is $25 is somewhat special. If the
     // symbol in the final relocation is external and not modified with a
     // constant then we must use R_MIPS_CALL16 instead of R_MIPS_GOT16.
     if ((DstReg == Mips::T9 || DstReg == Mips::T9_64) && !UseSrcReg &&
-        Res.getConstant() == 0 && !Res.getSymA()->getSymbol().isInSection() &&
-        !Res.getSymA()->getSymbol().isTemporary()) {
+        Res.getConstant() == 0 &&
+        !(Res.getSymA()->getSymbol().isInSection() ||
+          Res.getSymA()->getSymbol().isTemporary() ||
+          (Res.getSymA()->getSymbol().isELF() &&
+           cast<MCSymbolELF>(Res.getSymA()->getSymbol()).getBinding() ==
+               ELF::STB_LOCAL))) {
       const MCExpr *CallExpr =
           MipsMCExpr::create(MipsMCExpr::MEK_GOT_CALL, SymExpr, getContext());
       TOut.emitRRX(Mips::LW, DstReg, ABI.GetGlobalPtr(),
                    MCOperand::createExpr(CallExpr), IDLoc, STI);
       return false;
     }
 
     // The remaining cases are: