cmd/compile/internal/abi: fix ComputePadding

Fixes the ComputePadding calculation to take into account the padding
added for the current offset. This fixes an issue where padding can be
added incorrectly for certain structs.

Related: go-delve/delve#3923

Fixes golang#72053

Author: derekparker

src/cmd/compile/internal/abi/abiutils.go

@@ -679,9 +679,11 @@ func (pa *ABIParamAssignment) ComputePadding(storage []uint64) []uint64 {
 		off += int64(ts)
 		if idx < len(types)-1 {
 			noff := offsets[idx+1]
+			p := uint64(noff - off)
 			if noff != off {
-				padding[idx] = uint64(noff - off)
+				padding[idx] = p
 			}
+			off += int64(p)
 		}
 	}
 	return padding

src/cmd/compile/internal/ssa/debug.go

@@ -557,7 +557,7 @@ func PopulateABIInRegArgOps(f *Func) {
 	f.Entry.Values = append(newValues, f.Entry.Values...)
 }
 
-// BuildFuncDebug debug information for f, placing the results
+// BuildFuncDebug builds debug information for f, placing the results
 // in "rval". f must be fully processed, so that each Value is where it
 // will be when machine code is emitted.
 func BuildFuncDebug(ctxt *obj.Link, f *Func, loggingLevel int, stackOffset func(LocalSlot) int32, rval *FuncDebug) {

src/cmd/compile/internal/test/abiutils_test.go

@@ -390,9 +390,9 @@ func TestABIUtilsComputePadding(t *testing.T) {
 	padding := make([]uint64, 32)
 	parm := regRes.InParams()[1]
 	padding = parm.ComputePadding(padding)
-	want := "[1 1 1 0]"
+	want := "[1 0 0 0]"
 	got := fmt.Sprintf("%+v", padding)
 	if got != want {
-		t.Errorf("padding mismatch: wanted %q got %q\n", got, want)
+		t.Errorf("padding mismatch: wanted %q got %q\n", want, got)
 	}
 }

src/cmd/link/internal/ld/dwarf_test.go

@@ -5,7 +5,9 @@
 package ld
 
 import (
+	"bytes"
 	"debug/dwarf"
+	"debug/elf"
 	"debug/pe"
 	"fmt"
 	"internal/platform"
@@ -2042,3 +2044,115 @@ func TestConsistentGoKindAndRuntimeType(t *testing.T) {
 		t.Logf("%d types checked\n", typesChecked)
 	}
 }
+
+func TestIssue72053(t *testing.T) {
+	testenv.MustHaveGoBuild(t)
+
+	mustHaveDWARF(t)
+
+	t.Parallel()
+
+	dir := t.TempDir()
+
+	const prog = `package main
+
+import (
+		"fmt"
+		"strings"
+)
+
+func main() {
+		u := Address{Addr: "127.0.0.1"}
+		fmt.Println(u) // line 10
+}
+
+type Address struct {
+		TLS  bool
+		Addr string
+}
+
+func (a Address) String() string {
+		sb := new(strings.Builder)
+		sb.WriteString(a.Addr)
+		return sb.String()
+}
+`
+
+	bf := gobuild(t, dir, prog, NoOpt)
+
+	defer bf.Close()
+
+	f, err := elf.Open(bf.path)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	dwrf, err := f.DWARF()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	rdr := dwrf.Reader()
+
+	found := false
+	for {
+		e, err := rdr.Next()
+		if err != nil {
+			t.Fatal(err)
+		}
+		if e == nil {
+			break
+		}
+
+		name, _ := e.Val(dwarf.AttrName).(string)
+
+		switch e.Tag {
+		case dwarf.TagSubprogram:
+			if name == "main.Address.String" {
+				for {
+					e, err := rdr.Next()
+					if err != nil || e == nil {
+						break
+					}
+					name, _ := e.Val(dwarf.AttrName).(string)
+					if name == "a" {
+						loc := e.AttrField(dwarf.AttrLocation)
+						if loc != nil {
+							switch loc.Class {
+							case dwarf.ClassLocListPtr:
+								found = true
+								offset := loc.Val.(int64)
+								buf := make([]byte, 48)
+								s := f.Section(".debug_loc")
+								if s == nil {
+									t.Fatal("could not find debug_loc section")
+								}
+								d := s.Open()
+								d.Seek(offset, io.SeekStart)
+								d.Read(buf)
+
+								// DW_OP_reg0 DW_OP_piece 0x1 DW_OP_piece 0x7 DW_OP_reg3 DW_OP_piece 0x8 DW_OP_piece 0x7 DW_OP_reg2 DW_OP_piece 0x8
+								wrong := []byte{
+									0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+									0xa0, 0x2c, 0x49, 0x0, 0x0, 0x0, 0x0, 0x0,
+									0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0,
+									0x1f, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0,
+									0xd, 0x0, 0x50, 0x93, 0x1, 0x93, 0x7, 0x53,
+									0x93, 0x8, 0x93, 0x7, 0x52, 0x93, 0x8, 0x1f,
+								}
+
+								if bytes.Equal(buf, wrong) {
+									t.Fatal("unexpected DWARF sequence found")
+								}
+								break
+							}
+						}
+					}
+				}
+			}
+		}
+	}
+	if !found {
+		t.Fatal("unable to find expected DWARF location list")
+	}
+}