[llvm] 382c505 - [COFF] Fix ARM and ARM64 REL32 relocations to be relative to the end of the relocation

[Martin Storsjö via llvm-commits]

Author: Martin Storsjö
Date: 2021-05-12T09:53:43+03:00
New Revision: 382c505d9cfca8adaec47aea2da7bbcbc00fc05c

URL: https://github.com/llvm/llvm-project/commit/382c505d9cfca8adaec47aea2da7bbcbc00fc05c
DIFF: https://github.com/llvm/llvm-project/commit/382c505d9cfca8adaec47aea2da7bbcbc00fc05c.diff

LOG: [COFF] Fix ARM and ARM64 REL32 relocations to be relative to the end of the relocation

This matches how they are defined on X86.

This should fix the relative lookup tables pass for COFF, allowing
it to be reenabled.

Differential Revision: https://reviews.llvm.org/D102217

Added: 
    

Modified: 
    llvm/lib/MC/WinCOFFObjectWriter.cpp
    llvm/test/MC/AArch64/coff-relocations.s
    llvm/test/MC/ARM/coff-relocations.s

Removed: 
    


################################################################################
diff  --git a/llvm/lib/MC/WinCOFFObjectWriter.cpp b/llvm/lib/MC/WinCOFFObjectWriter.cpp
index 2a69a30a86c72..646f416821aea 100644
--- a/llvm/lib/MC/WinCOFFObjectWriter.cpp
+++ b/llvm/lib/MC/WinCOFFObjectWriter.cpp
@@ -789,12 +789,16 @@ void WinCOFFObjectWriter::recordRelocation(MCAssembler &Asm,
   Reloc.Data.Type = TargetObjectWriter->getRelocType(
       Asm.getContext(), Target, Fixup, SymB, Asm.getBackend());
 
-  // FIXME: Can anyone explain what this does other than adjust for the size
-  // of the offset?
+  // The *_REL32 relocations are relative to the end of the relocation,
+  // not to the start.
   if ((Header.Machine == COFF::IMAGE_FILE_MACHINE_AMD64 &&
        Reloc.Data.Type == COFF::IMAGE_REL_AMD64_REL32) ||
       (Header.Machine == COFF::IMAGE_FILE_MACHINE_I386 &&
-       Reloc.Data.Type == COFF::IMAGE_REL_I386_REL32))
+       Reloc.Data.Type == COFF::IMAGE_REL_I386_REL32) ||
+      (Header.Machine == COFF::IMAGE_FILE_MACHINE_ARMNT &&
+       Reloc.Data.Type == COFF::IMAGE_REL_ARM_REL32) ||
+      (Header.Machine == COFF::IMAGE_FILE_MACHINE_ARM64 &&
+       Reloc.Data.Type == COFF::IMAGE_REL_ARM64_REL32))
     FixedValue += 4;
 
   if (Header.Machine == COFF::IMAGE_FILE_MACHINE_ARMNT) {

diff  --git a/llvm/test/MC/AArch64/coff-relocations.s b/llvm/test/MC/AArch64/coff-relocations.s
index d0ebd073a09bc..e0fc30db6825c 100644
--- a/llvm/test/MC/AArch64/coff-relocations.s
+++ b/llvm/test/MC/AArch64/coff-relocations.s
@@ -109,4 +109,4 @@ tbz x0, #0, target
 // DISASM: 4c:       20 1a 09 30     adr     x0, #74565
 
 // DATA: Contents of section .rdata:
-// DATA-NEXT:  0000 2c000000 04000000
+// DATA-NEXT:  0000 30000000 08000000

diff  --git a/llvm/test/MC/ARM/coff-relocations.s b/llvm/test/MC/ARM/coff-relocations.s
index b2a4a92e5f8cd..32a95f973c0f2 100644
--- a/llvm/test/MC/ARM/coff-relocations.s
+++ b/llvm/test/MC/ARM/coff-relocations.s
@@ -120,4 +120,4 @@ secrel:
 @ CHECK-RELOCATION: ]
 
 @ CHECK-DATA: Contents of section .rdata:
-@ CHECK-DATA-NEXT: 0000 00000000 04000000
+@ CHECK-DATA-NEXT: 0000 04000000 08000000