Implemented register calls

src/asm/CanSkip.go

@@ -21,11 +21,11 @@ func (a *Assembler) CanSkip(mnemonic Mnemonic, left cpu.Register, right cpu.Regi
 			return false
 		}
 
-		if lastData.Destination == left && lastData.Source == right {
+		if lastData.Destination == right && lastData.Source == left {
 			return true
 		}
 
-		if lastData.Destination == right && lastData.Source == left {
+		if lastData.Destination == left && lastData.Source == right {
 			return true
 		}
 	}

src/asm/Instructions.go

@@ -10,16 +10,6 @@ func (a *Assembler) Comment(text string) {
 	})
 }
 
-// Call calls a function whose position is identified by a label.
-func (a *Assembler) Call(name string) {
-	a.Instructions = append(a.Instructions, Instruction{
-		Mnemonic: CALL,
-		Data: &Label{
-			Name: name,
-		},
-	})
-}
-
 // DLLCall calls a function in a DLL file.
 func (a *Assembler) DLLCall(name string) {
 	a.Instructions = append(a.Instructions, Instruction{

src/asmc/call.go

@@ -6,9 +6,10 @@ import (
 )
 
 func (c *compiler) call(x asm.Instruction) {
+	switch data := x.Data.(type) {
+	case *asm.Label:
 		c.code = x86.Call(c.code, 0x00_00_00_00)
 		size := 4
-	label := x.Data.(*asm.Label)
 
 		pointer := &pointer{
 			Position: Address(len(c.code) - size),
@@ -17,7 +18,7 @@ func (c *compiler) call(x asm.Instruction) {
 		}
 
 		pointer.Resolve = func() Address {
-		destination, exists := c.codeLabels[label.Name]
+			destination, exists := c.codeLabels[data.Name]
 
 			if !exists {
 				panic("unknown jump label")
@@ -28,4 +29,8 @@ func (c *compiler) call(x asm.Instruction) {
 		}
 
 		c.codePointers = append(c.codePointers, pointer)
+
+	case *asm.Register:
+		c.code = x86.CallRegister(c.code, data.Register)
+	}
 }

src/compiler/eachFunction.go

@@ -16,8 +16,13 @@ func (r *Result) eachFunction(caller *core.Function, traversed map[*core.Functio
 			continue
 		}
 
-		name := x.Data.(*asm.Label).Name
+		label, isLabel := x.Data.(*asm.Label)
-		callee, exists := r.Functions[name]
+
+		if !isLabel {
+			continue
+		}
+
+		callee, exists := r.Functions[label.Name]
 
 		if !exists {
 			continue

src/core/CallSafe.go

@@ -19,7 +19,7 @@ func (f *Function) CallSafe(fn *Function, registers []cpu.Register) {
 		}
 	}
 
-	f.Call(fn.UniqueName)
+	f.Label(asm.CALL, fn.UniqueName)
 
 	for _, register := range slices.Backward(f.CPU.General) {
 		if f.RegisterIsUsed(register) {

src/core/CompileCall.go

@@ -1,6 +1,7 @@
 package core
 
 import (
+	"git.urbach.dev/cli/q/src/asm"
 	"git.urbach.dev/cli/q/src/errors"
 	"git.urbach.dev/cli/q/src/expression"
 	"git.urbach.dev/cli/q/src/types"
@@ -45,13 +46,20 @@ func (f *Function) CompileCall(root *expression.Expression) ([]types.Type, error
 	}
 
 	if f.UniqueName == "core.init" && pkg == "main" && name == "main" {
-		f.Call("main.main")
+		f.Label(asm.CALL, "main.main")
 		return nil, nil
 	}
 
 	fn, exists = f.All.Functions[pkg+"."+name]
 
 	if !exists {
+		variable := f.VariableByName(name)
+
+		if variable != nil {
+			f.Register(asm.CALL, variable.Value.Register)
+			return nil, nil
+		}
+
 		return nil, errors.New(&errors.UnknownFunction{Name: name}, f.File, nameNode.Token.Position)
 	}
 

src/register/Call.go

@@ -1,7 +0,0 @@
-package register
-
-func (f *Machine) Call(label string) {
-	f.Assembler.Call(label)
-	f.UseRegister(f.CPU.Output[0])
-	f.postInstruction()
-}

src/register/Label.go

@@ -0,0 +1,8 @@
+package register
+
+import "git.urbach.dev/cli/q/src/asm"
+
+func (f *Machine) Label(mnemonic asm.Mnemonic, label string) {
+	f.Assembler.Label(mnemonic, label)
+	f.postInstruction()
+}

src/x86/Call.go

@@ -1,5 +1,7 @@
 package x86
 
+import "git.urbach.dev/cli/q/src/cpu"
+
 // Call places the return address on the top of the stack and continues
 // program flow at the new address.
 // The address is relative to the next instruction.
@@ -14,8 +16,25 @@ func Call(code []byte, address uint32) []byte {
 	)
 }
 
-// CallAtAddress places the return address on the top of the stack and
+// Calls a function whose address is stored in the given register.
-// continues program flow at the address stored at the given memory address.
+func CallRegister(code []byte, register cpu.Register) []byte {
+	if register > 0b111 {
+		return append(
+			code,
+			0x41,
+			0xFF,
+			0xD0+byte(register&0b111),
+		)
+	}
+
+	return append(
+		code,
+		0xFF,
+		0xD0+byte(register),
+	)
+}
+
+// CallAtAddress calls a function at the address stored at the given memory address.
 // The memory address is relative to the next instruction.
 func CallAtAddress(code []byte, address uint32) []byte {
 	return append(

src/x86/Call_test.go

@@ -0,0 +1,39 @@
+package x86_test
+
+import (
+	"testing"
+
+	"git.urbach.dev/cli/q/src/cpu"
+	"git.urbach.dev/cli/q/src/x86"
+	"git.urbach.dev/go/assert"
+)
+
+func TestCallRegister(t *testing.T) {
+	usagePatterns := []struct {
+		Register cpu.Register
+		Code     []byte
+	}{
+		{x86.RAX, []byte{0xFF, 0xD0}},
+		{x86.RCX, []byte{0xFF, 0xD1}},
+		{x86.RDX, []byte{0xFF, 0xD2}},
+		{x86.RBX, []byte{0xFF, 0xD3}},
+		{x86.RSP, []byte{0xFF, 0xD4}},
+		{x86.RBP, []byte{0xFF, 0xD5}},
+		{x86.RSI, []byte{0xFF, 0xD6}},
+		{x86.RDI, []byte{0xFF, 0xD7}},
+		{x86.R8, []byte{0x41, 0xFF, 0xD0}},
+		{x86.R9, []byte{0x41, 0xFF, 0xD1}},
+		{x86.R10, []byte{0x41, 0xFF, 0xD2}},
+		{x86.R11, []byte{0x41, 0xFF, 0xD3}},
+		{x86.R12, []byte{0x41, 0xFF, 0xD4}},
+		{x86.R13, []byte{0x41, 0xFF, 0xD5}},
+		{x86.R14, []byte{0x41, 0xFF, 0xD6}},
+		{x86.R15, []byte{0x41, 0xFF, 0xD7}},
+	}
+
+	for _, pattern := range usagePatterns {
+		t.Logf("call %s", pattern.Register)
+		code := x86.CallRegister(nil, pattern.Register)
+		assert.DeepEqual(t, code, pattern.Code)
+	}
+}

tests/errors/UnknownType.q

@@ -0,0 +1,5 @@
+main() {}
+
+f(x unknown) -> int {
+	return x
+}

tests/errors/UnknownType2.q

@@ -0,0 +1,5 @@
+main() {}
+
+f(x int) -> unknown {
+	return x
+}

tests/errors/UnusedVariable2.q

@@ -0,0 +1,3 @@
+main() {}
+
+f(x int) {}

tests/errors_test.go

@@ -58,10 +58,13 @@ var errs = []struct {
 	{"UnknownIdentifier2.q", &errors.UnknownIdentifier{Name: "x"}},
 	{"UnknownIdentifier3.q", &errors.UnknownIdentifier{Name: "x"}},
 	{"UnknownPackage.q", &errors.UnknownPackage{Name: "sys"}},
+	{"UnknownType.q", &errors.UnknownType{Name: "unknown"}},
+	{"UnknownType2.q", &errors.UnknownType{Name: "unknown"}},
 	{"UnknownStructField.q", &errors.UnknownStructField{StructName: "A", FieldName: "x"}},
 	{"UntypedExpression.q", errors.UntypedExpression},
 	{"UnusedImport.q", &errors.UnusedImport{Package: "sys"}},
 	{"UnusedVariable.q", &errors.UnusedVariable{Name: "x"}},
+	{"UnusedVariable2.q", &errors.UnusedVariable{Name: "x"}},
 	{"VariableAlreadyExists.q", &errors.VariableAlreadyExists{Name: "x"}},
 }
 

tests/programs/function-pointer.q

@@ -0,0 +1,6 @@
+import core
+
+main() {
+	exit := core.exit
+	exit()
+}

tests/programs_test.go

@@ -68,6 +68,7 @@ var programs = []struct {
 	{"struct", 0},
 	{"len", 0},
 	{"cast", 0},
+	{"function-pointer", 0},
 }
 
 func TestPrograms(t *testing.T) {