elf_reader: tolerate untyped/local map relocations from llvm 7/9

Symbols for anonymous constants are somewhat irregular on older versions
of LLVM. This commit relaxes the constraints on symbols those compilers
emit map relocations against.

LLVM 7:
     1: 0000000000000000     0 NOTYPE  LOCAL  DEFAULT    16 .Lconstinit.1

LLVM 9:
     1: 0000000000000000    32 OBJECT  LOCAL  DEFAULT    22 .Lconstinit.1

LLVM 14 has these symbols correctly sanitized.

Signed-off-by: Timo Beckers <[email protected]>

Author: ti-mo

elf_reader.go

@@ -468,12 +468,21 @@ func (ec *elfCode) relocateInstruction(ins *asm.Instruction, rel elf.Symbol) err
 			offset = uint32(uint64(ins.Constant))
 
 		case elf.STT_OBJECT:
-			if bind != elf.STB_GLOBAL {
+			// LLVM 9 emits OBJECT-LOCAL symbols for anonymous constants.
+			if bind != elf.STB_GLOBAL && bind != elf.STB_LOCAL {
 				return fmt.Errorf("direct load: %s: unsupported object relocation %s", name, bind)
 			}
 
 			offset = uint32(rel.Value)
 
+		case elf.STT_NOTYPE:
+			// LLVM 7 emits NOTYPE-LOCAL symbols for anonymous constants.
+			if bind != elf.STB_LOCAL {
+				return fmt.Errorf("direct load: %s: unsupported untyped relocation %s", name, bind)
+			}
+
+			offset = uint32(rel.Value)
+
 		default:
 			return fmt.Errorf("incorrect relocation type %v for direct map load", typ)
 		}