Track the compact unwind encoding for when we are unable to generate compact unwind...

Compact unwind has an encoding for when we're not able to generate compact
unwind and must generate an EH frame instead. Track that, but still emit that CU
encoding.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@179220 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/include/llvm/MC/MCObjectFileInfo.h b/include/llvm/MC/MCObjectFileInfo.h
index c8d748420e31b18d98715e01c8b314ede5a18db2..a5853b602c871c609bfd6264301f60968df4a62b 100644 (file)
--- a/include/llvm/MC/MCObjectFileInfo.h
+++ b/include/llvm/MC/MCObjectFileInfo.h
@@ -46,10 +46,15 @@ protected:
   unsigned FDEEncoding;
   unsigned FDECFIEncoding;
   unsigned TTypeEncoding;
-  // Section flags for eh_frame
+
+  /// Section flags for eh_frame
   unsigned EHSectionType;
   unsigned EHSectionFlags;
 
+  /// CompactUnwindDwarfEHFrameOnly - Compact unwind encoding indicating that we
+  /// should emit only an EH frame.
+  unsigned CompactUnwindDwarfEHFrameOnly;
+
   /// TextSection - Section directive for standard text.
   ///
   const MCSection *TextSection;
@@ -201,6 +206,10 @@ public:
   }
   unsigned getTTypeEncoding() const { return TTypeEncoding; }
 
+  unsigned getCompactUnwindDwarfEHFrameOnly() const {
+    return CompactUnwindDwarfEHFrameOnly;
+  }
+
   const MCSection *getTextSection() const { return TextSection; }
   const MCSection *getDataSection() const { return DataSection; }
   const MCSection *getBSSSection() const { return BSSSection; }

diff --git a/lib/MC/MCDwarf.cpp b/lib/MC/MCDwarf.cpp
index 0f8f0741bd7c898ee815fbbdfb52e074e695630c..9e003615d2ac5367b08f92e6f770ed4c19f2bf52 100644 (file)
--- a/lib/MC/MCDwarf.cpp
+++ b/lib/MC/MCDwarf.cpp
@@ -1168,10 +1168,10 @@ bool FrameEmitterImpl::EmitCompactUnwind(MCStreamer &Streamer,
   //   .quad except_tab1
 
   uint32_t Encoding = Frame.CompactUnwindEncoding;
-  if (!Encoding) return false;
+  bool DwarfEHFrameOnly = (Encoding == MOFI->getCompactUnwindDwarfEHFrameOnly());
 
   // The encoding needs to know we have an LSDA.
-  if (Frame.Lsda)
+  if (!DwarfEHFrameOnly && Frame.Lsda)
     Encoding |= 0x40000000;
 
   Streamer.SwitchSection(MOFI->getCompactUnwindSection());
@@ -1194,11 +1194,10 @@ bool FrameEmitterImpl::EmitCompactUnwind(MCStreamer &Streamer,
                                       Twine::utohexstr(Encoding));
   Streamer.EmitIntValue(Encoding, Size);
 
-
   // Personality Function
   Size = getSizeForEncoding(Streamer, dwarf::DW_EH_PE_absptr);
   if (VerboseAsm) Streamer.AddComment("Personality Function");
-  if (Frame.Personality)
+  if (!DwarfEHFrameOnly && Frame.Personality)
     Streamer.EmitSymbolValue(Frame.Personality, Size);
   else
     Streamer.EmitIntValue(0, Size); // No personality fn
@@ -1206,7 +1205,7 @@ bool FrameEmitterImpl::EmitCompactUnwind(MCStreamer &Streamer,
   // LSDA
   Size = getSizeForEncoding(Streamer, Frame.LsdaEncoding);
   if (VerboseAsm) Streamer.AddComment("LSDA");
-  if (Frame.Lsda)
+  if (!DwarfEHFrameOnly && Frame.Lsda)
     Streamer.EmitSymbolValue(Frame.Lsda, Size);
   else
     Streamer.EmitIntValue(0, Size); // No LSDA

diff --git a/lib/MC/MCObjectFileInfo.cpp b/lib/MC/MCObjectFileInfo.cpp
index d19e79ac64f9c2865b86b27cfb17779fd66b2b56..79ebad15e670fa93d969f85c3b53b63207281235 100644 (file)
--- a/lib/MC/MCObjectFileInfo.cpp
+++ b/lib/MC/MCObjectFileInfo.cpp
@@ -145,12 +145,16 @@ void MCObjectFileInfo::InitMachOMCObjectFileInfo(Triple T) {
   LSDASection = Ctx->getMachOSection("__TEXT", "__gcc_except_tab", 0,
                                      SectionKind::getReadOnlyWithRel());
 
-  if (T.isMacOSX() && !T.isMacOSXVersionLT(10, 6))
+  if (T.isMacOSX() && !T.isMacOSXVersionLT(10, 6)) {
     CompactUnwindSection =
       Ctx->getMachOSection("__LD", "__compact_unwind",
                            MCSectionMachO::S_ATTR_DEBUG,
                            SectionKind::getReadOnly());
 
+    if (T.getArch() == Triple::x86_64 || T.getArch() == Triple::x86)
+      CompactUnwindDwarfEHFrameOnly = 0x04000000;
+  }
+
   // Debug Information.
   DwarfAccelNamesSection =
     Ctx->getMachOSection("__DWARF", "__apple_names",
@@ -629,6 +633,8 @@ void MCObjectFileInfo::InitMCObjectFileInfo(StringRef TT, Reloc::Model relocm,
   PersonalityEncoding = LSDAEncoding = FDEEncoding = FDECFIEncoding =
     TTypeEncoding = dwarf::DW_EH_PE_absptr;
 
+  CompactUnwindDwarfEHFrameOnly = 0;
+
   EHFrameSection = 0;             // Created on demand.
   CompactUnwindSection = 0;       // Used only by selected targets.
   DwarfAccelNamesSection = 0;     // Used only by selected targets.