[ELF] Support some absolute/PC-relative relocation types for REL format

[MaskRay]

Summary

ctfconvert seems to use REL-format .rel.SUNW_dof for 32-bit architectures.

Binary file usr/ports/lang/perl5.32/work/perl-5.32.1/dtrace_mini.o matches
[alfredo.junior@dell-a ~/tmp/llvm-bug]$ readelf -r dtrace_mini.o

Relocation section (.rel.SUNW_dof):
r_offset r_info   r_type              st_value st_name
00000184 0000281a R_PPC_REL32         00000000 $dtrace1772974259.Perl_dtrace_probe_load

Support R_PPC_REL32 to fix ld.lld: error: drti.c:(.SUNW_dof+0x4E4): internal linker error: cannot read addend for relocation R_PPC_REL32.
While here, add some common relocation types for AArch64, PPC, and PPC64.
We perform minimum tests.

[arichardson]

LGTM

[adalava]

LGTM, Tested on FreeBSD/powerpc 32 bit

lld/ELF/Arch/AArch64.cpp

 }
 
 int64_t AArch64::getImplicitAddend(const uint8_t *buf, RelType type) const {
   switch (type) {
   case R_AARCH64_TLSDESC:
     return read64(buf + 8);
   case R_AARCH64_NONE:
     return 0;
+  case R_AARCH64_PREL32:
+    return SignExtend64<32>(read32(buf));
+  case R_AARCH64_ABS64:
+  case R_AARCH64_PREL64:
+    return read64(buf);
   default:
     internalLinkerError(getErrorLocation(buf),
                         "cannot read addend for relocation " + toString(type));
     return 0;
   }
 }
 
 void AArch64::writeGotPlt(uint8_t *buf, const Symbol &) const {

lld/ELF/Arch/PPC.cpp

if (type == R_PPC_ADDR32)
     return type;
   return R_PPC_NONE;
 }
 
 int64_t PPC::getImplicitAddend(const uint8_t *buf, RelType type) const {
   switch (type) {
   case R_PPC_NONE:
     return 0;
+  case R_PPC_ADDR32:
+  case R_PPC_REL32:
+    return SignExtend64<32>(read32(buf));
   default:
     internalLinkerError(getErrorLocation(buf),
                         "cannot read addend for relocation " + toString(type));
     return 0;
   }
 }
 
 static std::pair<RelType, uint64_t> fromDTPREL(RelType type, uint64_t val) {

lld/ELF/Arch/PPC64.cpp

if (type == R_PPC64_ADDR64 || type == R_PPC64_TOC)
     return R_PPC64_ADDR64;
   return R_PPC64_NONE;
 }
 
 int64_t PPC64::getImplicitAddend(const uint8_t *buf, RelType type) const {
   switch (type) {
   case R_PPC64_NONE:
     return 0;
+  case R_PPC64_REL32:
+    return SignExtend64<32>(read32(buf));
+  case R_PPC64_ADDR64:
+  case R_PPC64_REL64:
+    return read64(buf);
   default:
     internalLinkerError(getErrorLocation(buf),
                         "cannot read addend for relocation " + toString(type));
     return 0;
   }
 }
 
 void PPC64::writeGotHeader(uint8_t *buf) const {

lld/test/ELF/relocation-rel-format.test

+## Test some relocation types for REL format.
+# RUN: yaml2obj -DMACHINE=AARCH64 -DR0=R_AARCH64_ABS64 -DR1=R_AARCH64_PREL32 -DR2=R_AARCH64_PREL64 %s -o %t.o
+# RUN: ld.lld %t.o -o /dev/null
+# RUN: yaml2obj -DMACHINE=PPC -DBITS=32 -DR0=R_PPC_ADDR32 -DR1=R_PPC_REL32 %s -o %t.o
+# RUN: ld.lld %t.o -o /dev/null
+# RUN: yaml2obj -DMACHINE=PPC64 -DR0=R_PPC64_ADDR64 -DR1=R_PPC64_REL32 -DR2=R_PPC64_REL64 %s -o %t.o
+# RUN: ld.lld %t.o -o /dev/null
+
+--- !ELF
+FileHeader:
+  Class:   ELFCLASS[[BITS=64]]
+  Data:    ELFDATA2LSB
+  Type:    ET_REL
+  Machine: EM_[[MACHINE]]
+Sections:
+  - Name:  .text
+    Type:  SHT_PROGBITS
+    Flags: [ SHF_ALLOC, SHF_EXECINSTR ]
+    Size:  24
+  - Name:  .data
+    Type:  SHT_PROGBITS
+    Flags: [ SHF_WRITE, SHF_ALLOC ]
+  - Name:  .rel.text
+    Type:  SHT_REL
+    Info:  .text
+    Relocations:
+      - Symbol: .data
+        Type:   [[R0]]
+      - Offset: 8
+        Symbol: .data
+        Type:   [[R1=0]]
+      - Offset: 16
+        Symbol: .data
+        Type:   [[R2=0]]
+Symbols:
+  - Name:    .data
+    Type:    STT_SECTION
+    Section: .data
+  - Name:    _start
+    Section: .text
+    Binding: STB_GLOBAL
+...