all: add compiler support for interrupts

This commit lets the compiler know about interrupts and allows
optimizations to be performed based on that: interrupts are eliminated
when they appear to be unused in a program. This is done with a new
pseudo-call (runtime/interrupt.New) that is treated specially by the
compiler.

2 files changed, 21 insertions, 5 deletions

diff --git a/tools/gen-device-avr/gen-device-avr.go b/tools/gen-device-avr/gen-device-avr.go
index ac4c8b996..8f9298a21 100755
--- a/tools/gen-device-avr/gen-device-avr.go
+++ b/tools/gen-device-avr/gen-device-avr.go
@@ -260,6 +260,7 @@ func writeGo(outdir string, device *Device) error {
 package {{.pkgName}}
 
 import (
+	"runtime/interrupt"
 	"runtime/volatile"
 	"unsafe"
 )
@@ -277,6 +278,12 @@ const ({{range .interrupts}}
 	IRQ_max = {{.interruptMax}} // Highest interrupt number on this device.
 )
 
+// Map interrupt numbers to function names.
+// These aren't real calls, they're removed by the compiler.
+var ({{range .interrupts}}
+	_ = interrupt.Register(IRQ_{{.Name}}, "__vector_{{.Name}}"){{end}}
+)
+
 // Peripherals.
 var ({{range .peripherals}}
 	// {{.Caption}}
diff --git a/tools/gen-device-svd/gen-device-svd.go b/tools/gen-device-svd/gen-device-svd.go
index cef0365d5..f5aebcfe8 100755
--- a/tools/gen-device-svd/gen-device-svd.go
+++ b/tools/gen-device-svd/gen-device-svd.go
@@ -82,6 +82,7 @@ type Device struct {
 
 type interrupt struct {
 	Name            string
+	HandlerName     string
 	peripheralIndex int
 	Value           int // interrupt number
 	Description     string
@@ -171,12 +172,12 @@ func readSVD(path, sourceURL string) (*Device, error) {
 		groupName := cleanName(periphEl.GroupName)
 
 		for _, interrupt := range periphEl.Interrupts {
-			addInterrupt(interrupts, interrupt.Name, interrupt.Index, description)
+			addInterrupt(interrupts, interrupt.Name, interrupt.Name, interrupt.Index, description)
 			// As a convenience, also use the peripheral name as the interrupt
 			// name. Only do that for the nrf for now, as the stm32 .svd files
 			// don't always put interrupts in the correct peripheral...
 			if len(periphEl.Interrupts) == 1 && strings.HasPrefix(device.Name, "nrf") {
-				addInterrupt(interrupts, periphEl.Name, interrupt.Index, description)
+				addInterrupt(interrupts, periphEl.Name, interrupt.Name, interrupt.Index, description)
 			}
 		}
 
@@ -388,7 +389,7 @@ func readSVD(path, sourceURL string) (*Device, error) {
 	}, nil
 }
 
-func addInterrupt(interrupts map[string]*interrupt, name string, index int, description string) {
+func addInterrupt(interrupts map[string]*interrupt, name, interruptName string, index int, description string) {
 	if _, ok := interrupts[name]; ok {
 		if interrupts[name].Value != index {
 			// Note: some SVD files like the one for STM32H7x7 contain mistakes.
@@ -409,6 +410,7 @@ func addInterrupt(interrupts map[string]*interrupt, name string, index int, desc
 	} else {
 		interrupts[name] = &interrupt{
 			Name:            name,
+			HandlerName:     interruptName + "_IRQHandler",
 			peripheralIndex: len(interrupts),
 			Value:           index,
 			Description:     description,
@@ -619,6 +621,7 @@ func writeGo(outdir string, device *Device) error {
 package {{.pkgName}}
 
 import (
+	"runtime/interrupt"
 	"runtime/volatile"
 	"unsafe"
 )
@@ -628,12 +631,18 @@ const (
 	DEVICE	 = "{{.metadata.name}}"
 )
 
-// Interrupt numbers
+// Interrupt numbers.
 const ({{range .interrupts}}
 	IRQ_{{.Name}} = {{.Value}} // {{.Description}}{{end}}
 	IRQ_max = {{.interruptMax}} // Highest interrupt number on this device.
 )
 
+// Map interrupt numbers to function names.
+// These aren't real calls, they're removed by the compiler.
+var ({{range .interrupts}}
+	_ = interrupt.Register(IRQ_{{.Name}}, "{{.HandlerName}}"){{end}}
+)
+
 // Peripherals.
 var (
 {{range .peripherals}}	{{.Name}} = (*{{.GroupName}}_Type)(unsafe.Pointer(uintptr(0x{{printf "%x" .BaseAddress}}))) // {{.Description}}
@@ -879,7 +888,7 @@ Default_Handler:
 			num++
 		}
 		num++
-		fmt.Fprintf(w, "    .long %s_IRQHandler\n", intr.Name)
+		fmt.Fprintf(w, "    .long %s\n", intr.HandlerName)
 	}
 
 	w.WriteString(`