Generate compact unwind encoding from CFI directives.

We used to generate the compact unwind encoding from the machine
instructions. However, this had the problem that if the user used `-save-temps'
or compiled their hand-written `.s' file (with CFI directives), we wouldn't
generate the compact unwind encoding.

Move the algorithm that generates the compact unwind encoding into the
MCAsmBackend. This way we can generate the encoding whether the code is from a
`.ll' or `.s' file.

<rdar://problem/13623355>


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@190290 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 18 insertions, 5 deletions

diff --git a/include/llvm/MC/MCAsmBackend.h b/include/llvm/MC/MCAsmBackend.h
index 80272502df..27aaba9734 100644
--- a/include/llvm/MC/MCAsmBackend.h
+++ b/include/llvm/MC/MCAsmBackend.h
@@ -10,7 +10,9 @@
 #ifndef LLVM_MC_MCASMBACKEND_H
 #define LLVM_MC_MCASMBACKEND_H
 
+#include "llvm/ADT/ArrayRef.h"
 #include "llvm/MC/MCDirectives.h"
+#include "llvm/MC/MCDwarf.h"
 #include "llvm/MC/MCFixup.h"
 #include "llvm/Support/DataTypes.h"
 #include "llvm/Support/ErrorHandling.h"
@@ -158,6 +160,12 @@ public:
   /// handleAssemblerFlag - Handle any target-specific assembler flags.
   /// By default, do nothing.
   virtual void handleAssemblerFlag(MCAssemblerFlag Flag) {}
+
+  /// \brief Generate the compact unwind encoding for the CFI instructions.
+  virtual unsigned
+  generateCompactUnwindEncoding(ArrayRef<MCCFIInstruction>) const {
+    return 0;
+  }
 };
 
 } // End llvm namespace
diff --git a/include/llvm/MC/MCStreamer.h b/include/llvm/MC/MCStreamer.h
index 4aaaa35d43..c849e597b6 100644
--- a/include/llvm/MC/MCStreamer.h
+++ b/include/llvm/MC/MCStreamer.h
@@ -134,6 +134,8 @@ public:
     return *W64UnwindInfos[i];
   }
 
+  void generateCompactUnwindEncodings(MCAsmBackend &MAB);
+
   /// @name Assembly File Formatting.
   /// @{
 
diff --git a/include/llvm/Support/TargetRegistry.h b/include/llvm/Support/TargetRegistry.h
index 109b3a2fa3..9282853b88 100644
--- a/include/llvm/Support/TargetRegistry.h
+++ b/include/llvm/Support/TargetRegistry.h
@@ -104,6 +104,7 @@ namespace llvm {
     typedef AsmPrinter *(*AsmPrinterCtorTy)(TargetMachine &TM,
                                             MCStreamer &Streamer);
     typedef MCAsmBackend *(*MCAsmBackendCtorTy)(const Target &T,
+                                                const MCRegisterInfo &MRI,
                                                 StringRef TT,
                                                 StringRef CPU);
     typedef MCTargetAsmParser *(*MCAsmParserCtorTy)(MCSubtargetInfo &STI,
@@ -373,10 +374,11 @@ namespace llvm {
     /// createMCAsmBackend - Create a target specific assembly parser.
     ///
     /// \param Triple The target triple string.
-    MCAsmBackend *createMCAsmBackend(StringRef Triple, StringRef CPU) const {
+    MCAsmBackend *createMCAsmBackend(const MCRegisterInfo &MRI,
+                                     StringRef Triple, StringRef CPU) const {
       if (!MCAsmBackendCtorFn)
         return 0;
-      return MCAsmBackendCtorFn(*this, Triple, CPU);
+      return MCAsmBackendCtorFn(*this, MRI, Triple, CPU);
     }
 
     /// createMCAsmParser - Create a target specific assembly parser.
@@ -1118,9 +1120,10 @@ namespace llvm {
     }
 
   private:
-    static MCAsmBackend *Allocator(const Target &T, StringRef Triple,
-                                   StringRef CPU) {
-      return new MCAsmBackendImpl(T, Triple, CPU);
+    static MCAsmBackend *Allocator(const Target &T,
+                                   const MCRegisterInfo &MRI,
+                                   StringRef Triple, StringRef CPU) {
+      return new MCAsmBackendImpl(T, MRI, Triple, CPU);
     }
   };