compiler: add nounwind attribute

This attribute is also set by Clang when it compiles C source files
(unless -fexceptions is set). The advantage is that no unwind tables are
emitted on Linux (and perhaps other systems). It also avoids
__aeabi_unwind_cpp_pr0 on ARM when using the musl libc.

compiler/compiler.go

@@ -23,7 +23,7 @@ import (
 // Version of the compiler pacakge. Must be incremented each time the compiler
 // package changes in a way that affects the generated LLVM module.
 // This version is independent of the TinyGo version number.
-const Version = 20 // last change: fix export math functions issue
+const Version = 21 // last change: add nounwind attribute
 
 func init() {
 	llvm.InitializeAllTargets()
@@ -814,6 +814,7 @@ func (b *builder) createFunction() {
 		b.addError(b.fn.Pos(), errValue)
 		return
 	}
+	b.addStandardAttributes(b.llvmFn)
 	if !b.info.exported {
 		b.llvmFn.SetVisibility(llvm.HiddenVisibility)
 		b.llvmFn.SetUnnamedAddr(true)