debug/dwarf: support DW_FORM_rnglistx aka formRnglistx

Change-Id: I7df915978af3488f46a27595a1b04d0d33f81f7b
Reviewed-on: https://go-review.googlesource.com/c/go/+/302369
Trust: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Than McIntosh <thanm@google.com>

diff --git a/src/debug/dwarf/entry.go b/src/debug/dwarf/entry.go
index 3fc73b8ead29dbe0ab50fa96635d0d939a20b92a..9f5ac570803d4c4d351633155f51ddb679eb617e 100644 (file)
--- a/src/debug/dwarf/entry.go
+++ b/src/debug/dwarf/entry.go
@@ -317,7 +317,7 @@ const (
        // the "mac" section.
        ClassMacPtr
 
-       // ClassMacPtr represents values that are an int64 offset into
+       // ClassRangeListPtr represents values that are an int64 offset into
        // the "rangelist" section.
        ClassRangeListPtr
 
@@ -355,7 +355,7 @@ const (
        // into the "loclists" section.
        ClassLocList
 
-       // ClassRngList represents values that are an int64 offset
+       // ClassRngList represents values that are a uint64 offset
        // from the base of the "rnglists" section.
        ClassRngList
 
@@ -464,6 +464,35 @@ func (b *buf) entry(cu *Entry, atab abbrevTable, ubase Offset, vers int) *Entry
                return val
        }
 
+       resolveRnglistx := func(rnglistsBase, off uint64) uint64 {
+               is64, _ := b.format.dwarf64()
+               if is64 {
+                       off *= 8
+               } else {
+                       off *= 4
+               }
+               off += rnglistsBase
+               if uint64(int(off)) != off {
+                       b.error("DW_FORM_rnglistx offset out of range")
+               }
+
+               b1 := makeBuf(b.dwarf, b.format, "rnglists", 0, b.dwarf.rngLists)
+               b1.skip(int(off))
+               if is64 {
+                       off = b1.uint64()
+               } else {
+                       off = uint64(b1.uint32())
+               }
+               if b1.err != nil {
+                       b.err = b1.err
+                       return 0
+               }
+               if uint64(int(off)) != off {
+                       b.error("DW_FORM_rnglistx indirect offset out of range")
+               }
+               return rnglistsBase + off
+       }
+
        for i := range e.Field {
                e.Field[i].Attr = a.field[i].attr
                e.Field[i].Class = a.field[i].class
@@ -709,7 +738,21 @@ func (b *buf) entry(cu *Entry, atab abbrevTable, ubase Offset, vers int) *Entry
 
                // rnglist
                case formRnglistx:
-                       val = b.uint()
+                       off := b.uint()
+
+                       // We have to adjust by the rnglists_base of
+                       // the compilation unit. This won't work if
+                       // the program uses Reader.Seek to skip over
+                       // the unit. Not much we can do about that.
+                       var rnglistsBase int64
+                       if cu != nil {
+                               rnglistsBase, _ = cu.Val(AttrRnglistsBase).(int64)
+                       } else if a.tag == TagCompileUnit {
+                               delay = append(delay, delayed{i, off, formRnglistx})
+                               break
+                       }
+
+                       val = resolveRnglistx(uint64(rnglistsBase), off)
                }
 
                e.Field[i].Val = val
@@ -734,6 +777,12 @@ func (b *buf) entry(cu *Entry, atab abbrevTable, ubase Offset, vers int) *Entry
                        if b.err != nil {
                                return nil
                        }
+               case formRnglistx:
+                       rnglistsBase, _ := e.Val(AttrRnglistsBase).(int64)
+                       e.Field[del.idx].Val = resolveRnglistx(uint64(rnglistsBase), del.off)
+                       if b.err != nil {
+                               return nil
+                       }
                }
        }
 
@@ -993,8 +1042,15 @@ func (d *Data) Ranges(e *Entry) ([][2]uint64, error) {
                        return d.dwarf5Ranges(u, cu, base, ranges, ret)
 
                case ClassRngList:
-                       // TODO: support DW_FORM_rnglistx
-                       return ret, nil
+                       rnglist, ok := field.Val.(uint64)
+                       if !ok {
+                               return ret, nil
+                       }
+                       cu, base, err := d.baseAddressForEntry(e)
+                       if err != nil {
+                               return nil, err
+                       }
+                       return d.dwarf5Ranges(u, cu, base, int64(rnglist), ret)
 
                default:
                        return ret, nil

diff --git a/src/debug/dwarf/entry_test.go b/src/debug/dwarf/entry_test.go
index b54f8b4f8daa0405ded856afa331b37e9cbdc76f..1f41d742ea5de2916561339a7c790d2af1877286 100644 (file)
--- a/src/debug/dwarf/entry_test.go
+++ b/src/debug/dwarf/entry_test.go
@@ -84,6 +84,19 @@ func TestRangesSection(t *testing.T) {
        testRanges(t, "testdata/ranges.elf", want)
 }
 
+func TestRangesRnglistx(t *testing.T) {
+       want := []wantRange{
+               {0x401000, [][2]uint64{{0x401020, 0x40102c}, {0x401000, 0x40101d}}},
+               {0x40101c, [][2]uint64{{0x401020, 0x40102c}, {0x401000, 0x40101d}}},
+               {0x40101d, nil},
+               {0x40101f, nil},
+               {0x401020, [][2]uint64{{0x401020, 0x40102c}, {0x401000, 0x40101d}}},
+               {0x40102b, [][2]uint64{{0x401020, 0x40102c}, {0x401000, 0x40101d}}},
+               {0x40102c, nil},
+       }
+       testRanges(t, "testdata/rnglistx.elf", want)
+}
+
 func testRanges(t *testing.T, name string, want []wantRange) {
        d := elfData(t, name)
        r := d.Reader()

diff --git a/src/debug/dwarf/line_test.go b/src/debug/dwarf/line_test.go
index b13818e8b5082ec585ee253aa40814a0c4286b30..9c6b6ff5b0326674ca38b59fdea3c6ad383fd973 100644 (file)
--- a/src/debug/dwarf/line_test.go
+++ b/src/debug/dwarf/line_test.go
@@ -117,6 +117,29 @@ func TestLineELFClang(t *testing.T) {
        testLineTable(t, want, files, elfData(t, "testdata/line-clang.elf"))
 }
 
+func TestLineRnglists(t *testing.T) {
+       // Test a newer file, generated by clang.
+       file := &LineFile{Name: "/usr/local/google/home/iant/foo.c"}
+       want := []LineEntry{
+               {Address: 0x401020, File: file, Line: 12, IsStmt: true},
+               {Address: 0x401020, File: file, Line: 13, Column: 12, IsStmt: true, PrologueEnd: true},
+               {Address: 0x401022, File: file, Line: 13, Column: 7},
+               {Address: 0x401024, File: file, Line: 17, Column: 1, IsStmt: true},
+               {Address: 0x401027, File: file, Line: 16, Column: 10, IsStmt: true},
+               {Address: 0x40102c, EndSequence: true},
+               {Address: 0x401000, File: file, Line: 2, IsStmt: true},
+               {Address: 0x401000, File: file, Line: 6, Column: 17, IsStmt: true, PrologueEnd: true},
+               {Address: 0x401002, File: file, Line: 6, Column: 3},
+               {Address: 0x401019, File: file, Line: 9, Column: 3, IsStmt: true},
+               {Address: 0x40101a, File: file, Line: 0, Column: 3},
+               {Address: 0x40101c, File: file, Line: 9, Column: 3},
+               {Address: 0x40101d, EndSequence: true},
+       }
+       files := [][]*LineFile{{file}}
+
+       testLineTable(t, want, files, elfData(t, "testdata/rnglistx.elf"))
+}
+
 func TestLineSeek(t *testing.T) {
        d := elfData(t, "testdata/line-gcc.elf")
 

diff --git a/src/debug/dwarf/testdata/rnglistx.c b/src/debug/dwarf/testdata/rnglistx.c
new file mode 100644 (file)
index 0000000..8770435
--- /dev/null
+++ b/src/debug/dwarf/testdata/rnglistx.c
@@ -0,0 +1,19 @@
+// clang -gdwarf-5 -O2 -nostdlib
+
+__attribute__((noinline, cold))
+static int sum(int i) {
+  int j, s;
+
+  s = 0;
+  for (j = 0; j < i; j++) {
+    s += j * i;
+  }
+  return s;
+}
+
+int main(int argc, char** argv) {
+  if (argc == 0) {
+    return 0;
+  }
+  return sum(argc);
+}

diff --git a/src/debug/dwarf/testdata/rnglistx.elf b/src/debug/dwarf/testdata/rnglistx.elf
new file mode 100755 (executable)
index 0000000..c2d7f55
Binary files /dev/null and b/src/debug/dwarf/testdata/rnglistx.elf differ