[AArch64] Unconditionally use DW_EH_PE_indirect|DW_EH_PE_pcrel personality/lsda/ttype encodings

For -fno-pic, without DW_EH_PE_indirect, the personality routine pointer in a
CIE needs an R_AARCH64_ABS64 relocation. In common configurations that
`__gcc_personality_v0` is defined in a shared object, this will lead to a
discouraged canonical PLT entry, or, if `ld.lld -z notext` (betwen D122459 and
D143136), a dynamic R_AARCH64_ABS64 relocation with an incorrect offset:
https://github.com/llvm/llvm-project/issues/60392

Since GCC uses DW_EH_PE_indirect for -fno-pic code (the behavior hasn't changed
since the initial port in 2012), let's follow suit by simplifying the code.
(
For tiny and small code models, we use DW_EH_PE_sdata8 instead of GCC's
DW_EH_PE_sdata4. This is a deliberate choice to support personality-.eh_frame
offset > 2GiB. This is necessary for small code model since "Max text segment
size < 2GiB" but it is unnecessary to make `-fno-pic -mcmodel={tiny,small}`
different: The scenarios that uses both -fno-pic and C++ exceptions have been
increasingly rare now, so there is little advantage optimizing for the little
size saving with code complexity.
)

Reviewed By: MatzeB

Differential Revision: https://reviews.llvm.org/D143039

1 files changed, 8 insertions, 20 deletions

diff --git a/llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp b/llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
index 39f7ee7..bdb328f 100644
--- a/llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
+++ b/llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
@@ -182,26 +182,14 @@ void TargetLoweringObjectFileELF::Initialize(MCContext &Ctx,
     // The small model guarantees static code/data size < 4GB, but not where it
     // will be in memory. Most of these could end up >2GB away so even a signed
     // pc-relative 32-bit address is insufficient, theoretically.
-    if (isPositionIndependent()) {
-      // ILP32 uses sdata4 instead of sdata8
-      if (TgtM.getTargetTriple().getEnvironment() == Triple::GNUILP32) {
-        PersonalityEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
-                              dwarf::DW_EH_PE_sdata4;
-        LSDAEncoding = dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4;
-        TTypeEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
-                        dwarf::DW_EH_PE_sdata4;
-      } else {
-        PersonalityEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
-                              dwarf::DW_EH_PE_sdata8;
-        LSDAEncoding = dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata8;
-        TTypeEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
-                        dwarf::DW_EH_PE_sdata8;
-      }
-    } else {
-      PersonalityEncoding = dwarf::DW_EH_PE_absptr;
-      LSDAEncoding = dwarf::DW_EH_PE_absptr;
-      TTypeEncoding = dwarf::DW_EH_PE_absptr;
-    }
+    //
+    // Use DW_EH_PE_indirect even for -fno-pic to avoid copy relocations.
+    LSDAEncoding = dwarf::DW_EH_PE_pcrel |
+                   (TgtM.getTargetTriple().getEnvironment() == Triple::GNUILP32
+                        ? dwarf::DW_EH_PE_sdata4
+                        : dwarf::DW_EH_PE_sdata8);
+    PersonalityEncoding = LSDAEncoding | dwarf::DW_EH_PE_indirect;
+    TTypeEncoding = LSDAEncoding | dwarf::DW_EH_PE_indirect;
     break;
   case Triple::lanai:
     LSDAEncoding = dwarf::DW_EH_PE_absptr;