[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, 3 insertions, 0 deletions

diff --git a/llvm/lib/Target/TargetLoweringObjectFile.cpp b/llvm/lib/Target/TargetLoweringObjectFile.cpp
index 6bcf60fafc3..bb937923b47 100644
--- a/llvm/lib/Target/TargetLoweringObjectFile.cpp
+++ b/llvm/lib/Target/TargetLoweringObjectFile.cpp
@@ -45,6 +45,9 @@ void TargetLoweringObjectFile::Initialize(MCContext &ctx,
   Mang = new Mangler();
   InitMCObjectFileInfo(TM.getTargetTriple(), TM.isPositionIndependent(), *Ctx,
                        TM.getCodeModel() == CodeModel::Large);
+
+  // Reset various EH DWARF encodings.
+  PersonalityEncoding = LSDAEncoding = TTypeEncoding = dwarf::DW_EH_PE_absptr;
 }
 
 TargetLoweringObjectFile::~TargetLoweringObjectFile() {