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

[wzssyqa]

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.

[llvmbot]

@llvm/pr-subscribers-mc

Author: YunQiang Su (wzssyqa)

Changes

For asm code like:
xx:
la $2,$yy
$yy:
nop

MIPS O32 use $ as PrivateGlobalPrefix, while another $ is added for getOrCreateSymbol, thus:
error: Undefined temporary symbol $$yy

We also set symbols that starts with .L as local for O32.

See: #65020.

---

Full diff: https://github.com/llvm/llvm-project/pull/80644.diff

2 Files Affected:

• (modified) llvm/lib/Target/Mips/AsmParser/MipsAsmParser.cpp (+6-1)
• (added) llvm/test/MC/Mips/macro-la-local.s (+23)

diff --git a/llvm/lib/Target/Mips/AsmParser/MipsAsmParser.cpp b/llvm/lib/Target/Mips/AsmParser/MipsAsmParser.cpp
index 3c673ae938fde..2ddd8a6f31756 100644
--- a/llvm/lib/Target/Mips/AsmParser/MipsAsmParser.cpp
+++ b/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);
+    if (!IsLocalSym && ABI.IsO32()) {
+      // PrivateGlobalPrefix for O32 is '$', while we support '.L' anyway.
+      if (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());
diff --git a/llvm/test/MC/Mips/macro-la-local.s b/llvm/test/MC/Mips/macro-la-local.s
new file mode 100644
index 0000000000000..14c8e1b689ac9
--- /dev/null
+++ b/llvm/test/MC/Mips/macro-la-local.s
@@ -0,0 +1,23 @@
+# RUN: llvm-mc %s -triple=mips-unknown-linux -show-encoding -mcpu=mips32r2 | \
+# RUN:   FileCheck %s --check-prefixes=CHECK
+# RUN: llvm-mc %s -triple=mips-unknown-linux -show-encoding -mcpu=mips32r6 | \
+# RUN:   FileCheck %s --check-prefixes=CHECK
+
+	.text
+	.abicalls
+	.option	pic2
+xx:
+	la	$2,.Lhello #CHECK: lw      $2, %got(.Lhello)($gp)          # encoding: [0x8f,0x82,A,A]
+                           #CHECK: #   fixup A - offset: 0, value: %got(.Lhello), kind: fixup_Mips_GOT
+                           #CHECK: addiu   $2, $2, %lo(.Lhello)            # encoding: [0x24,0x42,A,A]
+                           #CHECK: #   fixup A - offset: 0, value: %lo(.Lhello), kind: fixup_Mips_LO16
+
+	la	$2,$hello2 #CHECK: lw      $2, %got($hello2)($gp)          # encoding: [0x8f,0x82,A,A]
+                           #CHECK: #   fixup A - offset: 0, value: %got($hello2), kind: fixup_Mips_GOT
+                           #CHECK: addiu   $2, $2, %lo($hello2)            # encoding: [0x24,0x42,A,A]
+                           #CHECK: #   fixup A - offset: 0, value: %lo($hello2), kind: fixup_Mips_LO16
+	.rdata
+.Lhello:
+	.asciz "Hello world\n"
+$hello2:
+	.asciz "Hello world\n"

[wzssyqa]

@MaskRay @brad0

[MaskRay]

# CHECK:      lw ...
# CHECK-NEXT:   fixup A ...
# CHECK-NEXT:   ...
la $2, $hello2

[MaskRay]

This comment is confusing.

// For O32, "$"-prefixed symbols are recognized as temporary while .L-prefixed symbols are not (PrivateGlobalPrefix is "$"). Recognize ".L" manually.

[MaskRay]

remove -unknown-linux whenever applicable, to emphasize that this is generic ELF behavior.

[github-actions]

✅ With the latest revision this PR passed the C/C++ code formatter.

[MaskRay]

Suggested description:

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.