MipsAsmParser/O32: Don't add redundant $ to $-prefixed symbol in the la macro (#80644)

When parsing the `la` macro, we add a duplicate `$` prefix in
`getOrCreateSymbol`,
leading to `error: Undefined temporary symbol $$yy` for code like:

```
xx:
	la	$2,$yy
$yy:
	nop
```

Remove the duplicate prefix.

In addition, recognize `.L`-prefixed symbols as local for O32.

See: #65020.

---------

Co-authored-by: Fangrui Song <[email protected]>

Author: wzssyqa

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

@@ -2920,6 +2920,11 @@ bool MipsAsmParser::loadAndAddSymbolAddress(const MCExpr *SymExpr,
         (Res.getSymA()->getSymbol().isELF() &&
          cast<MCSymbolELF>(Res.getSymA()->getSymbol()).getBinding() ==
              ELF::STB_LOCAL);
+    // For O32, "$"-prefixed symbols are recognized as temporary while
+    // .L-prefixed symbols are not (PrivateGlobalPrefix is "$"). Recognize ".L"
+    // manually.
+    if (ABI.IsO32() && Res.getSymA()->getSymbol().getName().starts_with(".L"))
+      IsLocalSym = true;
     bool UseXGOT = STI->hasFeature(Mips::FeatureXGOT) && !IsLocalSym;
 
     // The case where the result register is $25 is somewhat special. If the
@@ -6359,7 +6364,7 @@ bool MipsAsmParser::parseOperand(OperandVector &Operands, StringRef Mnemonic) {
       return true;
 
     SMLoc E = SMLoc::getFromPointer(Parser.getTok().getLoc().getPointer() - 1);
-    MCSymbol *Sym = getContext().getOrCreateSymbol("$" + Identifier);
+    MCSymbol *Sym = getContext().getOrCreateSymbol(Identifier);
     // Otherwise create a symbol reference.
     const MCExpr *SymRef =
         MCSymbolRefExpr::create(Sym, MCSymbolRefExpr::VK_None, getContext());

llvm/test/CodeGen/Mips/hf1_body.ll

@@ -23,8 +23,8 @@ entry:
 ; ALL:       .set reorder
 ; ALL:       .reloc 0, R_MIPS_NONE, v_sf
 ; GAS:       la $25, $__fn_local_v_sf
-; IAS:       lw $25, %got($$__fn_local_v_sf)($gp)
-; IAS:       addiu $25, $25, %lo($$__fn_local_v_sf)
+; IAS:       lw $25, %got($__fn_local_v_sf)($gp)
+; IAS:       addiu $25, $25, %lo($__fn_local_v_sf)
 ; ALL:       mfc1 $4, $f12
 ; ALL:       jr $25
 ; ALL:       .end __fn_stub_v_sf

llvm/test/MC/Mips/macro-la-pic.s

@@ -255,3 +255,25 @@ la $25, 2f
 # XN32: lw $25, %got_disp(.Ltmp1)($gp)  # encoding: [0x8f,0x99,A,A]
 # XN32:                                 #   fixup A - offset: 0, value: %got_disp(.Ltmp1), kind: fixup_Mips_GOT_DISP
 2:
+
+la $2,.Lstr
+# O32:      lw      $2, %got(.Lstr)($gp)          # encoding: [0x8f,0x82,A,A]
+# O32-NEXT:                           #   fixup A - offset: 0, value: %got(.Lstr), kind: fixup_Mips_GOT
+# O32-NEXT: addiu   $2, $2, %lo(.Lstr)            # encoding: [0x24,0x42,A,A]
+# O32-NEXT:                           #   fixup A - offset: 0, value: %lo(.Lstr), kind: fixup_Mips_LO16
+
+# N32:      lw      $2, %got_disp(.Lstr)($gp)     # encoding: [0x8f,0x82,A,A]
+# N32-NEXT:                           #   fixup A - offset: 0, value: %got_disp(.Lstr), kind: fixup_Mips_GOT_DISP
+
+la $2,$str2
+# O32:      lw      $2, %got($str2)($gp)          # encoding: [0x8f,0x82,A,A]
+# O32-NEXT: #   fixup A - offset: 0, value: %got($str2), kind: fixup_Mips_GOT
+# O32-NEXT: addiu   $2, $2, %lo($str2)            # encoding: [0x24,0x42,A,A]
+# O32-NEXT: #   fixup A - offset: 0, value: %lo($str2), kind: fixup_Mips_LO16
+
+# N32:      lw      $2, %got_disp($str2)($gp)     # encoding: [0x8f,0x82,A,A]
+# N32-NEXT:                           #   fixup A - offset: 0, value: %got_disp($str2), kind: fixup_Mips_GOT_DISP
+
+.rodata
+.Lstr: .4byte 0
+$str2: .4byte 0