[68]l: more robust decoding of reflection type info in generating dwarf.

R=rsc
CC=golang-dev, golang-dev
https://golang.org/cl/4106041

diff --git a/src/cmd/ld/dwarf.c b/src/cmd/ld/dwarf.c
index b724a98f5d21510f25744fcc3935ac263d5ae614..62f339d6ddff131d8747bb34be3169948a5890a9 100644 (file)
--- a/src/cmd/ld/dwarf.c
+++ b/src/cmd/ld/dwarf.c
@@ -798,6 +798,17 @@ decode_reloc(Sym *s, int32 off)
        return nil;
 }
 
+static Sym*
+decode_reloc_sym(Sym *s, int32 off)
+{
+       Reloc *r;
+
+       r = decode_reloc(s,off);
+       if (r == nil)
+               return nil;
+       return r->sym;
+}
+
 static uvlong
 decode_inuxi(uchar* p, int sz)
 {
@@ -851,7 +862,7 @@ decodetype_size(Sym *s)
 static Sym*
 decodetype_arrayelem(Sym *s)
 {
-       return decode_reloc(s, 5*PtrSize + 8)->sym;     // 0x1c / 0x30
+       return decode_reloc_sym(s, 5*PtrSize + 8);      // 0x1c / 0x30
 }
 
 static vlong
@@ -864,26 +875,26 @@ decodetype_arraylen(Sym *s)
 static Sym*
 decodetype_ptrelem(Sym *s)
 {
-       return decode_reloc(s, 5*PtrSize + 8)->sym;     // 0x1c / 0x30
+       return decode_reloc_sym(s, 5*PtrSize + 8);      // 0x1c / 0x30
 }
 
 // Type.MapType.key, elem
 static Sym*
 decodetype_mapkey(Sym *s)
 {
-       return decode_reloc(s, 5*PtrSize + 8)->sym;     // 0x1c / 0x30
+       return decode_reloc_sym(s, 5*PtrSize + 8);      // 0x1c / 0x30
 }
 static Sym*
 decodetype_mapvalue(Sym *s)
 {
-       return decode_reloc(s, 6*PtrSize + 8)->sym;     // 0x20 / 0x38
+       return decode_reloc_sym(s, 6*PtrSize + 8);      // 0x20 / 0x38
 }
 
 // Type.ChanType.elem
 static Sym*
 decodetype_chanelem(Sym *s)
 {
-       return decode_reloc(s, 5*PtrSize + 8)->sym;     // 0x1c / 0x30
+       return decode_reloc_sym(s, 5*PtrSize + 8);      // 0x1c / 0x30
 }
 
 // Type.FuncType.dotdotdot
@@ -912,7 +923,9 @@ decodetype_funcintype(Sym *s, int i)
        Reloc *r;
 
        r = decode_reloc(s, 6*PtrSize + 8);
-       return decode_reloc(r->sym, r->add + i * PtrSize)->sym;
+       if (r == nil)
+               return nil;
+       return decode_reloc_sym(r->sym, r->add + i * PtrSize);
 }
 
 static Sym*
@@ -921,7 +934,9 @@ decodetype_funcouttype(Sym *s, int i)
        Reloc *r;
 
        r = decode_reloc(s, 7*PtrSize + 16);
-       return decode_reloc(r->sym, r->add + i * PtrSize)->sym;
+       if (r == nil)
+               return nil;
+       return decode_reloc_sym(r->sym, r->add + i * PtrSize);
 }
 
 // Type.StructType.fields.Slice::len
@@ -935,21 +950,20 @@ decodetype_structfieldcount(Sym *s)
 static char*
 decodetype_structfieldname(Sym *s, int i)
 {
-       Reloc* r;
-
-       r = decode_reloc(s, 6*PtrSize + 0x10 + i*5*PtrSize);   // go.string."foo"  0x28 / 0x40
-       if (r == nil)                           // embedded structs have a nil name.
+       // go.string."foo"  0x28 / 0x40
+       s = decode_reloc_sym(s, 6*PtrSize + 0x10 + i*5*PtrSize);
+       if (s == nil)                   // embedded structs have a nil name.
                return nil;
-       r = decode_reloc(r->sym, 0);            // string."foo"
-       if (r == nil)                           // shouldn't happen.
+       s = decode_reloc_sym(s, 0);     // string."foo"
+       if (s == nil)                   // shouldn't happen.
                return nil;
-       return (char*)r->sym->p;                // the c-string
+       return (char*)s->p;             // the c-string
 }
 
 static Sym*
 decodetype_structfieldtype(Sym *s, int i)
 {
-       return decode_reloc(s, 8*PtrSize + 0x10 + i*5*PtrSize)->sym;     //   0x30 / 0x50
+       return decode_reloc_sym(s, 8*PtrSize + 0x10 + i*5*PtrSize);     //   0x30 / 0x50
 }
 
 static vlong