builder: sizes: list interrupt vector as a pseudo-package for -size=full

This is another bit of memory that is now correctly accounted for in
`-size=full`.

builder/sizes.go

@@ -371,7 +371,7 @@ func loadProgramSize(path string, packagePathMap map[string]string) (*programSiz
 			if section.Flags&elf.SHF_ALLOC == 0 {
 				continue
 			}
-			if packageSymbolRegexp.MatchString(symbol.Name) {
+			if packageSymbolRegexp.MatchString(symbol.Name) || symbol.Name == "__isr_vector" {
 				addresses = append(addresses, addressLine{
 					Address:    symbol.Value,
 					Length:     symbol.Size,
@@ -834,6 +834,8 @@ func findPackagePath(path string, packagePathMap map[string]string) string {
 		} else if packageSymbolRegexp.MatchString(path) {
 			// Parse symbol names like main$alloc or runtime$string.
 			packagePath = path[:strings.LastIndex(path, "$")]
+		} else if path == "__isr_vector" {
+			packagePath = "C interrupt vector"
 		} else if path == "<Go type>" {
 			packagePath = "Go types"
 		} else if path == "<Go interface assert>" {

targets/cortex-m-qemu.s

@@ -23,6 +23,7 @@ Default_Handler:
 
 .section .isr_vector, "a", %progbits
 .global  __isr_vector
+__isr_vector:
     // Interrupt vector as defined by Cortex-M, starting with the stack top.
     // On reset, SP is initialized with *0x0 and PC is loaded with *0x4, loading
     // _stack_top and Reset_Handler.
@@ -54,3 +55,5 @@ Default_Handler:
     IRQ DebugMon_Handler
     IRQ PendSV_Handler
     IRQ SysTick_Handler
+
+.size __isr_vector, .-__isr_vector

tools/gen-device-svd/gen-device-svd.go

@@ -1422,6 +1422,9 @@ __isr_vector:
 	for _, intr := range device.Interrupts {
 		fmt.Fprintf(w, "    IRQ %s_IRQHandler\n", intr.Name)
 	}
+	w.WriteString(`
+.size __isr_vector, .-__isr_vector
+`)
 	return w.Flush()
 }