createSyscalln emits instructions for the syscall.syscalln function on Windows. This handles the variadic calling convention used in Go 1.26+: func syscalln(fn, n uintptr, args ...uintptr) (r1, r2 uintptr, err Errno) The function generates a switch on n to dispatch to the correct fixed-argument f
(call *ssa.CallCommon)
| 357 | // The function generates a switch on n to dispatch to the correct fixed-argument |
| 358 | // function pointer call with SetLastError(0)/GetLastError() wrapping. |
| 359 | func (b *builder) createSyscalln(call *ssa.CallCommon) (llvm.Value, error) { |
| 360 | const maxArgs = 18 // Windows syscalls support up to 18 args |
| 361 | |
| 362 | isI386 := strings.HasPrefix(b.Triple, "i386-") |
| 363 | |
| 364 | // Get the function pointer (call.Args[0]) and n (call.Args[1]). |
| 365 | fn := b.getValue(call.Args[0], getPos(call)) |
| 366 | fnPtr := b.CreateIntToPtr(fn, b.dataPtrType, "") |
| 367 | n := b.getValue(call.Args[1], getPos(call)) |
| 368 | |
| 369 | // Get the variadic args slice (call.Args[2]). |
| 370 | // In SSA, the variadic slice is the third argument. |
| 371 | var argsPtr llvm.Value |
| 372 | if len(call.Args) > 2 { |
| 373 | argsSlice := b.getValue(call.Args[2], getPos(call)) |
| 374 | argsPtr = b.CreateExtractValue(argsSlice, 0, "args.data") |
| 375 | } else { |
| 376 | argsPtr = llvm.ConstNull(b.dataPtrType) |
| 377 | } |
| 378 | |
| 379 | // Prepare SetLastError and GetLastError. |
| 380 | setLastError := b.mod.NamedFunction("SetLastError") |
| 381 | if setLastError.IsNil() { |
| 382 | llvmType := llvm.FunctionType(b.ctx.VoidType(), []llvm.Type{b.ctx.Int32Type()}, false) |
| 383 | setLastError = llvm.AddFunction(b.mod, "SetLastError", llvmType) |
| 384 | if isI386 { |
| 385 | setLastError.SetFunctionCallConv(llvm.X86StdcallCallConv) |
| 386 | } |
| 387 | } |
| 388 | getLastError := b.mod.NamedFunction("GetLastError") |
| 389 | if getLastError.IsNil() { |
| 390 | llvmType := llvm.FunctionType(b.ctx.Int32Type(), nil, false) |
| 391 | getLastError = llvm.AddFunction(b.mod, "GetLastError", llvmType) |
| 392 | if isI386 { |
| 393 | getLastError.SetFunctionCallConv(llvm.X86StdcallCallConv) |
| 394 | } |
| 395 | } |
| 396 | |
| 397 | retType := b.ctx.StructType([]llvm.Type{b.uintptrType, b.uintptrType, b.uintptrType}, false) |
| 398 | |
| 399 | // Create the merge block where all cases converge. |
| 400 | mergeBB := b.insertBasicBlock("syscalln.merge") |
| 401 | |
| 402 | // Create the default (panic) block. |
| 403 | panicBB := b.insertBasicBlock("syscalln.panic") |
| 404 | |
| 405 | // Create the switch on n. |
| 406 | sw := b.CreateSwitch(n, panicBB, maxArgs+1) |
| 407 | |
| 408 | // We'll collect blocks and values for the PHI node. |
| 409 | var incomingVals []llvm.Value |
| 410 | var incomingBlocks []llvm.BasicBlock |
| 411 | |
| 412 | // Generate a case for each arg count 0..maxArgs. |
| 413 | for i := 0; i <= maxArgs; i++ { |
| 414 | caseBB := b.insertBasicBlock("syscalln.case" + strconv.Itoa(i)) |
| 415 | sw.AddCase(llvm.ConstInt(b.uintptrType, uint64(i), false), caseBB) |
| 416 | b.SetInsertPointAtEnd(caseBB) |
no test coverage detected