[MC] Move EH DWARF encodings from MC to CodeGen, NFC

Summary:
The TType encoding, LSDA encoding, and personality encoding are all
passed explicitly by CodeGen to the assembler through .cfi_* directives,
so only the AsmPrinter needs to know about them.

The FDE CFI encoding however, controls the encoding of the label
implicitly created by the .cfi_startproc directive. That directive seems
to be special in that it doesn't take an encoding, so the assembler just
has to know how to encode one DSO-local label reference from .eh_frame
to .text.

As a result, it looks like MC will continue to have to know when the
large code model is in use. Perhaps we could invent a '.cfi_startproc
[large]' flag so that this knowledge doesn't need to pollute the
assembler.

Reviewers: davide, lliu0, JDevlieghere

Subscribers: hiraditya, fedor.sergeev, llvm-commits

Differential Revision: https://reviews.llvm.org/D50533

llvm-svn: 339397

1 files changed, 5 insertions, 157 deletions

diff --git a/llvm/lib/MC/MCObjectFileInfo.cpp b/llvm/lib/MC/MCObjectFileInfo.cpp
index b88d2d8..8f1ca4e 100644
--- a/llvm/lib/MC/MCObjectFileInfo.cpp
+++ b/llvm/lib/MC/MCObjectFileInfo.cpp
@@ -63,11 +63,7 @@ void MCObjectFileInfo::initMachOMCObjectFileInfo(const Triple &T) {
   if (T.isWatchABI())
     OmitDwarfIfHaveCompactUnwind = true;
 
-  PersonalityEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel
-    | dwarf::DW_EH_PE_sdata4;
-  LSDAEncoding = FDECFIEncoding = dwarf::DW_EH_PE_pcrel;
-  TTypeEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
-    dwarf::DW_EH_PE_sdata4;
+  FDECFIEncoding = dwarf::DW_EH_PE_pcrel;
 
   // .comm doesn't support alignment before Leopard.
   if (T.isMacOSX() && T.isMacOSXVersionLT(10, 5))
@@ -311,158 +307,11 @@ void MCObjectFileInfo::initELFMCObjectFileInfo(const Triple &T, bool Large) {
   case Triple::bpfeb:
     FDECFIEncoding = dwarf::DW_EH_PE_sdata8;
     break;
-  default:
-    FDECFIEncoding = dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4;
-    break;
-  }
-
-  switch (T.getArch()) {
-  case Triple::arm:
-  case Triple::armeb:
-  case Triple::thumb:
-  case Triple::thumbeb:
-    if (Ctx->getAsmInfo()->getExceptionHandlingType() == ExceptionHandling::ARM)
-      break;
-    // Fallthrough if not using EHABI
-    LLVM_FALLTHROUGH;
-  case Triple::ppc:
-  case Triple::x86:
-    PersonalityEncoding = PositionIndependent
-                              ? dwarf::DW_EH_PE_indirect |
-                                    dwarf::DW_EH_PE_pcrel |
-                                    dwarf::DW_EH_PE_sdata4
-                              : dwarf::DW_EH_PE_absptr;
-    LSDAEncoding = PositionIndependent
-                       ? dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4
-                       : dwarf::DW_EH_PE_absptr;
-    TTypeEncoding = PositionIndependent
-                        ? dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
-                              dwarf::DW_EH_PE_sdata4
-                        : dwarf::DW_EH_PE_absptr;
-    break;
-  case Triple::x86_64:
-    if (PositionIndependent) {
-      PersonalityEncoding =
-          dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
-          (Large ? dwarf::DW_EH_PE_sdata8 : dwarf::DW_EH_PE_sdata4);
-      LSDAEncoding = dwarf::DW_EH_PE_pcrel |
-                     (Large ? dwarf::DW_EH_PE_sdata8 : dwarf::DW_EH_PE_sdata4);
-      TTypeEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
-                      (Large ? dwarf::DW_EH_PE_sdata8 : dwarf::DW_EH_PE_sdata4);
-    } else {
-      PersonalityEncoding =
-          Large ? dwarf::DW_EH_PE_absptr : dwarf::DW_EH_PE_udata4;
-      LSDAEncoding = Large ? dwarf::DW_EH_PE_absptr : dwarf::DW_EH_PE_udata4;
-      TTypeEncoding = Large ? dwarf::DW_EH_PE_absptr : dwarf::DW_EH_PE_udata4;
-    }
-    break;
   case Triple::hexagon:
-    PersonalityEncoding = dwarf::DW_EH_PE_absptr;
-    LSDAEncoding = dwarf::DW_EH_PE_absptr;
-    FDECFIEncoding = dwarf::DW_EH_PE_absptr;
-    TTypeEncoding = dwarf::DW_EH_PE_absptr;
-    if (PositionIndependent) {
-      PersonalityEncoding |= dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel;
-      LSDAEncoding |= dwarf::DW_EH_PE_pcrel;
-      FDECFIEncoding |= dwarf::DW_EH_PE_pcrel;
-      TTypeEncoding |= dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel;
-    }
-    break;
-  case Triple::aarch64:
-  case Triple::aarch64_be:
-    // 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 (PositionIndependent) {
-      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;
-    }
-    break;
-  case Triple::lanai:
-    LSDAEncoding = dwarf::DW_EH_PE_absptr;
-    PersonalityEncoding = dwarf::DW_EH_PE_absptr;
-    TTypeEncoding = dwarf::DW_EH_PE_absptr;
-    break;
-  case Triple::mips:
-  case Triple::mipsel:
-  case Triple::mips64:
-  case Triple::mips64el:
-    // MIPS uses indirect pointer to refer personality functions and types, so
-    // that the eh_frame section can be read-only. DW.ref.personality will be
-    // generated for relocation.
-    PersonalityEncoding = dwarf::DW_EH_PE_indirect;
-    // FIXME: The N64 ABI probably ought to use DW_EH_PE_sdata8 but we can't
-    //        identify N64 from just a triple.
-    TTypeEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
-                    dwarf::DW_EH_PE_sdata4;
-    // We don't support PC-relative LSDA references in GAS so we use the default
-    // DW_EH_PE_absptr for those.
-
-    // FreeBSD must be explicit about the data size and using pcrel since it's
-    // assembler/linker won't do the automatic conversion that the Linux tools
-    // do.
-    if (T.isOSFreeBSD()) {
-      PersonalityEncoding |= dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4;
-      LSDAEncoding = dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4;
-    }
-    break;
-  case Triple::ppc64:
-  case Triple::ppc64le:
-    PersonalityEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
-      dwarf::DW_EH_PE_udata8;
-    LSDAEncoding = dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_udata8;
-    TTypeEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
-      dwarf::DW_EH_PE_udata8;
-    break;
-  case Triple::sparcel:
-  case Triple::sparc:
-    if (PositionIndependent) {
-      LSDAEncoding = dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4;
-      PersonalityEncoding = dwarf::DW_EH_PE_indirect | 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 {
-      LSDAEncoding = dwarf::DW_EH_PE_absptr;
-      PersonalityEncoding = dwarf::DW_EH_PE_absptr;
-      TTypeEncoding = dwarf::DW_EH_PE_absptr;
-    }
-    break;
-  case Triple::sparcv9:
-    LSDAEncoding = dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4;
-    if (PositionIndependent) {
-      PersonalityEncoding = dwarf::DW_EH_PE_indirect | 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_absptr;
-      TTypeEncoding = dwarf::DW_EH_PE_absptr;
-    }
-    break;
-  case Triple::systemz:
-    // All currently-defined code models guarantee that 4-byte PC-relative
-    // values will be in range.
-    if (PositionIndependent) {
-      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_absptr;
-      LSDAEncoding = dwarf::DW_EH_PE_absptr;
-      TTypeEncoding = dwarf::DW_EH_PE_absptr;
-    }
-    break;
+    FDECFIEncoding =
+        PositionIndependent ? dwarf::DW_EH_PE_pcrel : dwarf::DW_EH_PE_absptr;
   default:
+    FDECFIEncoding = dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4;
     break;
   }
 
@@ -908,8 +757,7 @@ void MCObjectFileInfo::InitMCObjectFileInfo(const Triple &TheTriple, bool PIC,
   SupportsCompactUnwindWithoutEHFrame = false;
   OmitDwarfIfHaveCompactUnwind = false;
 
-  PersonalityEncoding = LSDAEncoding = FDECFIEncoding = TTypeEncoding =
-      dwarf::DW_EH_PE_absptr;
+  FDECFIEncoding = dwarf::DW_EH_PE_absptr;
 
   CompactUnwindDwarfEHFrameOnly = 0;