[lld] f457863 - [ELF] Support REL-format R_AARCH64_NONE relocation

[Fangrui Song via llvm-commits]

Author: Fangrui Song
Date: 2022-02-04T13:20:49-08:00
New Revision: f457863ae345d2635026501f5383e0e625869639

URL: https://github.com/llvm/llvm-project/commit/f457863ae345d2635026501f5383e0e625869639
DIFF: https://github.com/llvm/llvm-project/commit/f457863ae345d2635026501f5383e0e625869639.diff

LOG: [ELF] Support REL-format R_AARCH64_NONE relocation

-fprofile-use=/-fprofile-sample-use= compiles may produce REL-format
.rel.llvm.call-graph-profile even if the prevailing format is RELA on AArch64.
Add R_AARCH64_NONE to getImplicitAddend to fix this linker error:

```
ld.lld: error: internal linker error: cannot read addend for relocation R_AARCH64_NONE
PLEASE submit a bug report to https://crbug.com and run tools/clang/scripts/process_crashreports.py (only works inside Google) which will upload a report and include the crash backtrace.
```

Added: 
    lld/test/ELF/relocation-none-aarch64.test

Modified: 
    lld/ELF/Arch/AArch64.cpp

Removed: 
    lld/test/ELF/relocation-none-aarch64.s


################################################################################
diff  --git a/lld/ELF/Arch/AArch64.cpp b/lld/ELF/Arch/AArch64.cpp
index 5789bc935b638..9e857d5906845 100644
--- a/lld/ELF/Arch/AArch64.cpp
+++ b/lld/ELF/Arch/AArch64.cpp
@@ -197,6 +197,8 @@ 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;
   default:
     internalLinkerError(getErrorLocation(buf),
                         "cannot read addend for relocation " + toString(type));

diff  --git a/lld/test/ELF/relocation-none-aarch64.s b/lld/test/ELF/relocation-none-aarch64.s
deleted file mode 100644
index 7783c127cf867..0000000000000
--- a/lld/test/ELF/relocation-none-aarch64.s
+++ /dev/null
@@ -1,26 +0,0 @@
-# REQUIRES: aarch64
-
-# RUN: llvm-mc -filetype=obj -triple=aarch64-linux-musl %s -o %t.o
-# RUN: ld.lld --gc-sections %t.o -o %t
-# RUN: llvm-readelf -S -r %t | FileCheck %s
-
-# Test that we discard R_AARCH64_NONE, but respect the references it creates
-# among sections.
-
-# CHECK: .data
-# CHECK: There are no relocations in this file.
-
-# RUN: ld.lld -r %t.o -o %t
-# RUN: llvm-readobj -r %t | FileCheck --check-prefix=RELOC %s
-
-# RELOC:      Section ({{.*}}) .rela.text {
-# RELOC-NEXT:   0x0 R_AARCH64_NONE .data 0x0
-# RELOC-NEXT: }
-
-.globl _start
-_start:
-  ret
-  .reloc 0, R_AARCH64_NONE, .data
-
-.data
-  .long 0

diff  --git a/lld/test/ELF/relocation-none-aarch64.test b/lld/test/ELF/relocation-none-aarch64.test
new file mode 100644
index 0000000000000..0147085021f7a
--- /dev/null
+++ b/lld/test/ELF/relocation-none-aarch64.test
@@ -0,0 +1,69 @@
+# REQUIRES: aarch64
+# RUN: yaml2obj %s -o %t.o
+# RUN: ld.lld --gc-sections %t.o -o %t
+# RUN: llvm-readelf -S -r %t | FileCheck %s
+
+## Test that we discard R_AARCH64_NONE, but respect the references it creates
+## among sections.
+
+# CHECK: .data
+# CHECK: There are no relocations in this file.
+
+# RUN: ld.lld -r %t.o -o %t
+# RUN: llvm-readobj -r %t | FileCheck --check-prefix=RELOC %s
+
+## Both REL and RELA are supported. .rel.llvm.call-graph-profile uses REL even
+## if the prevailing format is RELA.
+# RELOC:      Section ({{.*}}) .rela.text {
+# RELOC-NEXT:   0x0 R_AARCH64_NONE .data 0x0
+# RELOC-NEXT: }
+# RELOC:      Section ({{.*}}) .rel.nonalloc1 {
+# RELOC-NEXT:   0x0 R_AARCH64_NONE .data
+# RELOC-NEXT: }
+# RELOC:      Section ({{.*}}) .rela.nonalloc2 {
+# RELOC-NEXT:   0x0 R_AARCH64_NONE .data 0x0
+# RELOC-NEXT: }
+
+--- !ELF
+FileHeader:
+  Class:           ELFCLASS64
+  Data:            ELFDATA2LSB
+  Type:            ET_REL
+  Machine:         EM_AARCH64
+Sections:
+  - Name:            .text
+    Type:            SHT_PROGBITS
+    Flags:           [ SHF_ALLOC, SHF_EXECINSTR ]
+  - Name:            .data
+    Type:            SHT_PROGBITS
+    Flags:           [ SHF_WRITE, SHF_ALLOC ]
+  - Name:            .nonalloc1
+    Type:            SHT_PROGBITS
+  - Name:            .nonalloc2
+    Type:            SHT_PROGBITS
+  - Name:            .rela.text
+    Type:            SHT_RELA
+    Info:            .text
+    Relocations:
+      - Symbol:          .data
+        Type:            R_AARCH64_NONE
+  - Name:            .rel.nonalloc1
+    Type:            SHT_REL
+    Info:            .nonalloc1
+    Relocations:
+      - Symbol:          .data
+        Type:            R_AARCH64_NONE
+  - Name:            .rela.nonalloc2
+    Type:            SHT_RELA
+    Info:            .nonalloc2
+    Relocations:
+      - Symbol:          .data
+        Type:            R_AARCH64_NONE
+Symbols:
+  - Name:            .data
+    Type:            STT_SECTION
+    Section:         .data
+  - Name:            _start
+    Section:         .text
+    Binding:         STB_GLOBAL
+...