[LLVMdev] How to define a function with multiple return values?

[Tzu-Chien Chiu]

LegalizeDAG.cpp

  SDOperand SelectionDAGLegalize::LegalizeOp(SDOperand Op) {
    case ISD::RET:
      Tmp1 = LegalizeOp(Node->getOperand(0));  // Legalize the chain.
      switch (Node->getNumOperands()) {
      case 2:  // ret val
      [skipped]
      case 1:  // ret void
      [skipped]
      default: { // ret <values>
      [skipped]

Does it imply that a ret instruction may return more than one values?

  ret uint 1, uint 2, ubyte 3, uint 4

But at most one return value is allowed, according to
http://llvm.cs.uiuc.edu/docs/LangRef.html#i_ret

  Syntax:

    ret <type> <value>       ; Return a value from a non-void function
    ret void                 ; Return from void function

How to define a function with multiple return values? The code:

  uint, uint, ubyte, uint %main() {
    ret uint 1, uint 2, ubyte 3, uint 4
  }

cannot be correctly assembled by llvm-as.


-- 
Tzu-Chien Chiu,
3D Graphics Hardware Architect
<URL:http://www.csie.nctu.edu.tw/~jwchiu>