From 3cba36f2ba789a7680d9bef98acb5f84bdcfbdf8 Mon Sep 17 00:00:00 2001
From: Ayke van Laethem <aykevanlaethem@gmail.com>
Date: Tue, 5 Feb 2019 20:13:39 +0100
Subject: [PATCH] compiler: add syscalls for 64-bit arm

---
 .travis.yml         |  2 ++
 compiler/syscall.go | 35 +++++++++++++++++++++++++++++++++++
 main_test.go        | 10 ++++++++++
 target.go           |  3 ++-
 4 files changed, 49 insertions(+), 1 deletion(-)

diff --git a/.travis.yml b/.travis.yml
index 40f2b8c7..365a6df8 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -18,6 +18,8 @@ addons:
     - gcc-arm-linux-gnueabi
     - binutils-arm-none-eabi
     - libc6-dev-armel-cross
+    - gcc-aarch64-linux-gnu
+    - libc6-dev-arm64-cross
     - qemu-system-arm
     - qemu-user
     - gcc-avr
diff --git a/compiler/syscall.go b/compiler/syscall.go
index 6ba6535d..fc9235d3 100644
--- a/compiler/syscall.go
+++ b/compiler/syscall.go
@@ -81,6 +81,41 @@ func (c *Compiler) emitSyscall(frame *Frame, call *ssa.CallCommon) (llvm.Value,
 		fnType := llvm.FunctionType(c.uintptrType, argTypes, false)
 		target := llvm.InlineAsm(fnType, "svc #0", constraints, true, false, 0)
 		syscallResult = c.builder.CreateCall(target, args, "")
+	case c.GOARCH == "arm64" && c.GOOS == "linux":
+		// Source: syscall(2) man page.
+		args := []llvm.Value{}
+		argTypes := []llvm.Type{}
+		// Constraints will look something like:
+		//   ={x0},0,{x1},{x2},{x8},~{x3},~{x4},~{x5},~{x6},~{x7},~{x16},~{x17}
+		constraints := "={x0}"
+		for i, arg := range call.Args[1:] {
+			constraints += "," + [...]string{
+				"0", // tie to output
+				"{x1}",
+				"{x2}",
+				"{x3}",
+				"{x4}",
+				"{x5}",
+			}[i]
+			llvmValue, err := c.parseExpr(frame, arg)
+			if err != nil {
+				return llvm.Value{}, err
+			}
+			args = append(args, llvmValue)
+			argTypes = append(argTypes, llvmValue.Type())
+		}
+		args = append(args, llvm.ConstInt(c.uintptrType, num, false))
+		argTypes = append(argTypes, c.uintptrType)
+		constraints += ",{x8}" // syscall number
+		for i := len(call.Args) - 1; i < 8; i++ {
+			// x0-x7 may get clobbered during the syscall following the aarch64
+			// calling convention.
+			constraints += ",~{x" + strconv.Itoa(i) + "}"
+		}
+		constraints += ",~{x16},~{x17}" // scratch registers
+		fnType := llvm.FunctionType(c.uintptrType, argTypes, false)
+		target := llvm.InlineAsm(fnType, "svc #0", constraints, true, false, 0)
+		syscallResult = c.builder.CreateCall(target, args, "")
 	default:
 		return llvm.Value{}, c.makeError(call.Pos(), "unknown GOOS/GOARCH for syscall: "+c.GOOS+"/"+c.GOARCH)
 	}
diff --git a/main_test.go b/main_test.go
index 2882c227..f1e164d8 100644
--- a/main_test.go
+++ b/main_test.go
@@ -63,6 +63,16 @@ func TestCompiler(t *testing.T) {
 		})
 	}
 
+	t.Log("running tests for linux/arm64...")
+	for _, path := range matches {
+		if path == "testdata/cgo/" {
+			continue // TODO: improve CGo
+		}
+		t.Run(path, func(t *testing.T) {
+			runTest(path, tmpdir, "aarch64--linux-gnueabi", t)
+		})
+	}
+
 	t.Log("running tests for emulated cortex-m3...")
 	for _, path := range matches {
 		t.Run(path, func(t *testing.T) {
diff --git a/target.go b/target.go
index 141be076..a85e6561 100644
--- a/target.go
+++ b/target.go
@@ -224,10 +224,11 @@ func defaultTarget(goos, goarch, triple string) (*TargetSpec, error) {
 			spec.GDB = "arm-linux-gnueabi-gdb"
 			spec.Emulator = []string{"qemu-arm", "-L", "/usr/arm-linux-gnueabi"}
 		}
-		if goarch == "arm64" {
+		if goarch == "arm64" && goos == "linux" {
 			spec.Linker = "aarch64-linux-gnu-gcc"
 			spec.Objcopy = "aarch64-linux-gnu-objcopy"
 			spec.GDB = "aarch64-linux-gnu-gdb"
+			spec.Emulator = []string{"qemu-aarch64", "-L", "/usr/aarch64-linux-gnu"}
 		}
 		if goarch == "386" {
 			spec.CFlags = []string{"-m32"}