SDKtoGhidra: apply the XML's calling convention when importing functions

[jatassi]

Problem

ImportSporeSDK.java resolves each function's calling convention from the function's existing convention (getCallingConvention(Function, FunctionSignature, CompilerSpec) returns function.getCallingConventionName()). After Ghidra's auto-analysis that is always unknown, so the CONVENTION attribute the XML carries on 3,662 thiscall and 203 stdcall definitions is never used. The this-in-ECX branch in createParameters therefore never runs: this is placed at stack offset 4 and every stack argument of a __thiscall function is shifted by four bytes.

Example, Editors::EditorModel::SetColor before the fix:

void Editors__EditorModel__SetColor(EditorModel *this,int index,ColorRGB color)
{
  int *piVar1;
  int in_ECX;
  piVar1 = (int *)(in_ECX + 0xa4 + (int)this * 0xc);
  *piVar1 = index;
  ...

The real this is in_ECX, the parameter named this is the real index, and index is the first word of color.

A second, related problem: processFunctionDef stores the convention through the deprecated FunctionDefinition.setGenericCallingConvention, which in Ghidra 11+ stores the bare enum name (thiscall). No compiler spec recognises that name, so every definition reports hasUnknownCallingConventionName() == true, and the decompiler treats calls through __vftable slots (whose members are pointers to these definitions) as unknown-convention calls.

Fix

• getCallingConvention(String) now maps the XML's cdecl/fastcall/stdcall/thiscall/vectorcall/unknown to the CompilerSpec.CALLING_CONVENTION_* names, and processFunctionDef stores that name with FunctionDefinition.setCallingConvention.
• getCallingConvention(Function, FunctionSignature, CompilerSpec) returns the definition's convention when the program's compiler spec knows it, and the function's existing convention otherwise.
• Custom storage is kept as before. With dynamic storage the typed this is lost, because the functions live in Ghidra's global namespace with :: in their names and Ghidra only derives an auto-this inside a class namespace.
• The error message for an unknown CONVENTION value now prints the offending text instead of null.

Tested

Ghidra 12.1.3, JDK 21, SporeGhidra_march2017.xml against the GOG SporeApp.exe:

• Editors::EditorModel::SetColor decompiles to this->mColors[index].r = color.r; ....
• App::Property::GetValueInt32 reads this-> in its body.
• Math::RandomNumberGenerator::RandomFloat (returns float) still returns in st0.
• Imported function count is unchanged; imported functions with a signature now report __thiscall or __stdcall instead of unknown.

Found while building an annotated project for the OpenSpore effort (https://github.com/jatassi/OpenSpore).

[Rosalie241]

Found while building an annotated project for the OpenSpore effort (https://github.com/jatassi/OpenSpore).

That link doesn't work but I presume it's also mostly LLM generated?

[Rosalie241]

After some internal discussion with the other maintainers, we've decided we will not accept LLM generated patches.