commit f8e47e4868270ee1bea61a5b64f3df5153262a08
author Tim Northover <tnorthover@apple.com> Wed Oct 28 22:56:36 2015 +0000
committer Tim Northover <tnorthover@apple.com> Wed Oct 28 22:56:36 2015 +0000
tree adb4e7c6c66481f3cd0c2d4ee0d01aec0fef532a
parent 2253d1c0525d2a30c0a9e6e26237dabc6237b9b4

ARM: add support for WatchOS's compact unwind information.

llvm-svn: 251573

llvm/lib/MC/MCDwarf.cpp

diff --git a/llvm/lib/MC/MCDwarf.cpp b/llvm/lib/MC/MCDwarf.cpp
index e964032..8be1f4c 100644
--- a/llvm/lib/MC/MCDwarf.cpp
+++ b/llvm/lib/MC/MCDwarf.cpp
@@ -1536,6 +1536,7 @@
 
   const MCSymbol *DummyDebugKey = nullptr;
   NeedsEHFrameSection = !MOFI->getSupportsCompactUnwindWithoutEHFrame();
+  bool CanOmitDwarf = MOFI->getOmitDwarfIfHaveCompactUnwind();
   for (unsigned i = 0, n = FrameArray.size(); i < n; ++i) {
     const MCDwarfFrameInfo &Frame = FrameArray[i];
 
@@ -1545,7 +1546,7 @@
       FDEEnd = nullptr;
     }
 
-    if (!NeedsEHFrameSection && Frame.CompactUnwindEncoding !=
+    if (CanOmitDwarf && Frame.CompactUnwindEncoding !=
           MOFI->getCompactUnwindDwarfEHFrameOnly())
       // Don't generate an EH frame if we don't need one. I.e., it's taken care
       // of by the compact unwind encoding.

llvm/lib/MC/MCObjectFileInfo.cpp

diff --git a/llvm/lib/MC/MCObjectFileInfo.cpp b/llvm/lib/MC/MCObjectFileInfo.cpp
index 666a1c3..4c51c83 100644
--- a/llvm/lib/MC/MCObjectFileInfo.cpp
+++ b/llvm/lib/MC/MCObjectFileInfo.cpp
@@ -29,6 +29,10 @@
   if (T.getArch() == Triple::aarch64)
     return true;
 
+  // armv7k always has it.
+  if (T.isWatchOS())
+    return true;
+
   // Use it on newer version of OS X.
   if (T.isMacOSX() && !T.isMacOSXVersionLT(10, 6))
     return true;
@@ -48,6 +52,9 @@
   if (T.isOSDarwin() && T.getArch() == Triple::aarch64)
     SupportsCompactUnwindWithoutEHFrame = true;
 
+  if (T.isWatchOS())
+    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;
@@ -193,9 +200,11 @@
                              SectionKind::getReadOnly());
 
     if (T.getArch() == Triple::x86_64 || T.getArch() == Triple::x86)
-      CompactUnwindDwarfEHFrameOnly = 0x04000000;
+      CompactUnwindDwarfEHFrameOnly = 0x04000000;  // UNWIND_X86_64_MODE_DWARF
     else if (T.getArch() == Triple::aarch64)
-      CompactUnwindDwarfEHFrameOnly = 0x03000000;
+      CompactUnwindDwarfEHFrameOnly = 0x03000000;  // UNWIND_ARM64_MODE_DWARF
+    else if (T.getArch() == Triple::arm || T.getArch() == Triple::thumb)
+      CompactUnwindDwarfEHFrameOnly = 0x04000000;  // UNWIND_ARM_MODE_DWARF
   }
 
   // Debug Information.
@@ -767,6 +776,7 @@
   CommDirectiveSupportsAlignment = true;
   SupportsWeakOmittedEHFrame = true;
   SupportsCompactUnwindWithoutEHFrame = false;
+  OmitDwarfIfHaveCompactUnwind = false;
 
   PersonalityEncoding = LSDAEncoding = FDECFIEncoding = TTypeEncoding =
       dwarf::DW_EH_PE_absptr;