openjdk/jdk · warning

Warning: ThreadLocal instruction

Error message

Warning: ThreadLocal instruction %s should be named 'tlsLoadP_*'

What it means

ADLC naming-convention warning from InstructForm::is_tls_instruction(): the instruction's match rule references the ThreadLocal ideal node, but its identifier does not follow the required 'tlsLoadP' / 'tlsLoadP_*' convention. The instruction is still classified as a TLS instruction (returns 1), but the warning flags that downstream generated code relies on the name prefix for TLS handling.

Solutions

1. Rename the instruction to 'tlsLoadP' or with the 'tlsLoadP_' prefix
2. If the name cannot change, verify the generated matcher still handles the instruction correctly
3. Rebuild to confirm the warning is gone

Example fix

// before
instruct loadTLS(iRegP reg) %{ match(Set reg (ThreadLocal)); %}

// after
instruct tlsLoadP_slow(iRegP reg) %{ match(Set reg (ThreadLocal)); %}

grep -nP 'instruct\s+(?!tlsLoadP)\w+.*ThreadLocal' src/hotspot/cpu/x86/x86.ad 2>/dev/null || true # flag instructions matching ThreadLocal with wrong names

When it happens

Trigger: Defining an instruct whose match rule's opType (after unwrapping a 'Set') is 'ThreadLocal' while naming the instruction something other than tlsLoadP or tlsLoadP_something. The check inspects _ident and the matrule/insencode pair.

Common situations: Adding or renaming thread-local load instructions during HotSpot porting; naming a new TLS access helper 'loadTLS' instead of 'tlsLoadP_slow'.

Related errors

• Error Context: >>>%c<<<
• ERROR: More than one register has been assigned…
• error: node is null
• error: operand \" \" not found
• Error: Out of memory in ADLC\n

AI-assisted analysis of openjdk/jdk@88dfb74bbe (2026-08-14). Data as JSON: /api/errors/9084919950ed1e11. Report an issue: GitHub.

Appendix: source

Thrown at src/hotspot/share/adlc/formssel.cpp:304

  if (_size != nullptr && strcmp(_size, "0") == 0) {
    return 1;
  }
  return 0;
}

int InstructForm::is_tls_instruction() const {
  if (_ident != nullptr &&
      ( ! strcmp( _ident,"tlsLoadP") ||
        ! strncmp(_ident,"tlsLoadP_",9)) ) {
    return 1;
  }

  if (_matrule != nullptr && _insencode != nullptr) {
    const char* opType = _matrule->_opType;
    if (strcmp(opType, "Set")==0)
      opType = _matrule->_rChild->_opType;
    if (strcmp(opType,"ThreadLocal")==0) {
      fprintf(stderr, "Warning: ThreadLocal instruction %s should be named 'tlsLoadP_*'\n",
              (_ident == nullptr ? "nullptr" : _ident));
      return 1;
    }
  }

  return 0;
}


// Return 'true' if this instruction matches an ideal 'If' node
bool InstructForm::is_ideal_if() const {
  if( _matrule == nullptr ) return false;

  return _matrule->is_ideal_if();
}

// Return 'true' if this instruction matches an ideal 'FastLock' node
bool InstructForm::is_ideal_fastlock() const {

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