RFR: 8325467: Support methods with many arguments in C2 [v27]

[Daniel Lundén]

On Tue, 16 Sep 2025 14:27:51 GMT, Emanuel Peter <epeter at openjdk.org> wrote:

>> The ADLC-generated code relies on using the constructor implicitly, so I prefer not touching it in this changeset at least. All the copies are deep, clarified now.
>
> Ok, I understand. Can you show me an example, so I can understand a little better?

Here is an example (compiled from different files). The constructor gets called when converting from reference to value at the return of `divI_proj_mask`. We could fix this by making the return type of  `Matcher::divI_proj_mask` `RegMask&` and updating `UDivModINode::match` accordingly, but I regard this as out of scope for this already large PR. I'd be happy to have a look at this in a follow-up PR.


const RegMask _INT_RAX_REG_mask( 0x100000, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, false );

inline const RegMask &INT_RAX_REG_mask() { return _INT_RAX_REG_mask; }

// Register for DIVI projection of divmodI
RegMask Matcher::divI_proj_mask() {
  return INT_RAX_REG_mask();
}

//------------------------------match------------------------------------------
// return result(s) along with their RegMask info
Node* UDivModINode::match( const ProjNode *proj, const Matcher *match ) {
  uint ideal_reg = proj->ideal_reg();
  RegMask rm;
  if (proj->_con == div_proj_num) {
    rm = match->divI_proj_mask();
  } else {
    assert(proj->_con == mod_proj_num, "must be div or mod projection");
    rm = match->modI_proj_mask();
  }
  return new MachProjNode(this, proj->_con, rm, ideal_reg);
}

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PR Review Comment: https://git.openjdk.org/jdk/pull/20404#discussion_r2354848956