Emit DWARF3 call frame information when DWARF3+ debug info is requested

Currently, llvm always emits a DWARF CIE with a version of 1, even when emitting
DWARF 3 or 4, which both support CIE version 3. This patch makes it emit the
newer CIE version when we are emitting DWARF 3 or 4. This will not reduce
compatibility, as we already emit other DWARF3/4 features, and is worth doing as
the DWARF3 spec removed some ambiguities in the interpretation of call frame
information.

It also fixes a minor bug where the "return address" field of the CIE was
encoded as a ULEB128, which is only valid when the CIE version is 3. There are
no test changes for this, because (as far as I can tell) none of the platforms
that we test have a return address register with a DWARF register number >127.

llvm-svn: 211272

1 files changed, 2 insertions, 0 deletions

diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
index 7aaf731b6f8..3847eb124f3 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -209,6 +209,8 @@ DwarfDebug::DwarfDebug(AsmPrinter *A, Module *M)
   DwarfVersion = DwarfVersionNumber ? DwarfVersionNumber
                                     : MMI->getModule()->getDwarfVersion();
 
+  Asm->OutStreamer.getContext().setDwarfVersion(DwarfVersion);
+
   {
     NamedRegionTimer T(DbgTimerName, DWARFGroupName, TimePassesIsEnabled);
     beginModule();