go-llvm: expose exact source-location APIs

dibuilder.go

@@ -60,8 +60,17 @@ const (
 type DwarfLang uint32
 
 const (
-	// http://dwarfstd.org/ShowIssue.php?issue=101014.1&type=open
-	DW_LANG_Go DwarfLang = 0x0016
+	// LLVMDWARFSourceLanguage is a dense C API enum, not the raw DW_LANG
+	// encoding from the DWARF specification.
+	DW_LANG_Go DwarfLang = C.LLVMDWARFSourceLanguageGo
+)
+
+type DwarfEmissionKind uint8
+
+const (
+	DwarfEmissionFull DwarfEmissionKind = iota
+	DwarfEmissionLineTablesOnly
+	DwarfEmissionNone
 )
 
 type DwarfTypeEncoding uint32
@@ -120,6 +129,7 @@ type DICompileUnit struct {
 	RuntimeVersion int
 	SysRoot        string
 	SDK            string
+	EmissionKind   DwarfEmissionKind
 }
 
 // CreateCompileUnit creates compile unit debug metadata.
@@ -136,6 +146,16 @@ func (d *DIBuilder) CreateCompileUnit(cu DICompileUnit) Metadata {
 	defer C.free(unsafe.Pointer(sysroot))
 	sdk := C.CString(cu.SDK)
 	defer C.free(unsafe.Pointer(sdk))
+	emissionKind := C.LLVMDWARFEmissionKind(C.LLVMDWARFEmissionFull)
+	switch cu.EmissionKind {
+	case DwarfEmissionFull:
+	case DwarfEmissionLineTablesOnly:
+		emissionKind = C.LLVMDWARFEmissionLineTablesOnly
+	case DwarfEmissionNone:
+		emissionKind = C.LLVMDWARFEmissionNone
+	default:
+		panic("invalid DWARF emission kind")
+	}
 	result := C.LLVMDIBuilderCreateCompileUnit(
 		d.ref,
 		C.LLVMDWARFSourceLanguage(cu.Language),
@@ -145,7 +165,7 @@ func (d *DIBuilder) CreateCompileUnit(cu DICompileUnit) Metadata {
 		flags, C.size_t(len(cu.Flags)),
 		C.unsigned(cu.RuntimeVersion),
 		/*SplitName=*/ nil, 0,
-		C.LLVMDWARFEmissionFull,
+		emissionKind,
 		/*DWOId=*/ 0,
 		/*SplitDebugInlining*/ C.LLVMBool(boolToCInt(true)),
 		/*DebugInfoForProfiling*/ C.LLVMBool(boolToCInt(false)),
@@ -155,6 +175,13 @@ func (d *DIBuilder) CreateCompileUnit(cu DICompileUnit) Metadata {
 	return Metadata{C: result}
 }
 
+// CreateDebugLocation creates an exact DILocation, including an optional
+// inlinedAt chain.
+func (c Context) CreateDebugLocation(line, col uint, scope, inlinedAt Metadata) Metadata {
+	return Metadata{C: C.LLVMDIBuilderCreateDebugLocation(
+		c.C, C.uint(line), C.uint(col), scope.C, inlinedAt.C)}
+}
+
 // CreateFile creates file debug metadata.
 func (d *DIBuilder) CreateFile(filename, dir string) Metadata {
 	cfilename := C.CString(filename)

ir.go

@@ -1390,6 +1390,20 @@ func (b Builder) SetCurrentDebugLocation(line, col uint, scope, inlinedAt Metada
 	C.LLVMGoSetCurrentDebugLocation(b.C, C.unsigned(line), C.unsigned(col), scope.C, inlinedAt.C)
 }
 
+// SetCurrentDebugLocationMetadata sets the exact DILocation inherited by
+// subsequently created instructions. A nil value clears it.
+func (b Builder) SetCurrentDebugLocationMetadata(loc Metadata) {
+	C.LLVMSetCurrentDebugLocation2(b.C, loc.C)
+}
+
+func (b Builder) CurrentDebugLocationMetadata() Metadata {
+	return Metadata{C: C.LLVMGetCurrentDebugLocation2(b.C)}
+}
+
+func (b Builder) ClearCurrentDebugLocation() {
+	C.LLVMSetCurrentDebugLocation2(b.C, nil)
+}
+
 // Get current debug location. Please do not call this function until setting debug location with SetCurrentDebugLocation()
 func (b Builder) GetCurrentDebugLocation() (loc DebugLoc) {
 	md := C.LLVMGoGetCurrentDebugLocation(b.C)

ir_test.go

@@ -244,6 +244,40 @@ func TestDebugLoc(t *testing.T) {
 	if loc.Scope.C != scope.C {
 		t.Errorf("Got metadata %v as scope, though wanted %v", loc.Scope.C, scope.C)
 	}
+
+	exact := ctx.CreateDebugLocation(11, 7, scope, Metadata{})
+	b.SetCurrentDebugLocationMetadata(exact)
+	if got := b.CurrentDebugLocationMetadata(); got.C != exact.C {
+		t.Errorf("Got exact location %v, want %v", got.C, exact.C)
+	}
+	b.ClearCurrentDebugLocation()
+	if got := b.CurrentDebugLocationMetadata(); !got.IsNil() {
+		t.Errorf("Cleared debug location is non-nil: %v", got.C)
+	}
+}
+
+func TestGoCompileUnitLanguageAndEmission(t *testing.T) {
+	ctx := NewContext()
+	defer ctx.Dispose()
+	mod := ctx.NewModule("go-debug")
+	defer mod.Dispose()
+	d := NewDIBuilder(mod)
+	defer d.Destroy()
+
+	d.CreateCompileUnit(DICompileUnit{
+		Language:     DW_LANG_Go,
+		File:         "debug.go",
+		Producer:     "go-llvm-test",
+		EmissionKind: DwarfEmissionLineTablesOnly,
+	})
+	d.Finalize()
+	text := mod.String()
+	if !strings.Contains(text, "language: DW_LANG_Go") {
+		t.Fatalf("compile unit does not use the Go source language:\n%s", text)
+	}
+	if !strings.Contains(text, "emissionKind: LineTablesOnly") {
+		t.Fatalf("compile unit does not use line-tables-only emission:\n%s", text)
+	}
 }
 
 func TestSubtypes(t *testing.T) {