Re-apply r211399, "Generate native unwind info on Win64" with a fix to ignore SEH pseudo ops in X86 JIT emitter.

--
This patch enables LLVM to emit Win64-native unwind info rather than
DWARF CFI.  It handles all corner cases (I hope), including stack
realignment.

Because the unwind info is not flexible enough to describe stack frames
with a gap of unknown size in the middle, such as the one caused by
stack realignment, I modified register spilling code to place all spills
into the fixed frame slots, so that they can be accessed relative to the
frame pointer.

Patch by Vadim Chugunov!

Reviewed By: rnk

Differential Revision: http://reviews.llvm.org/D4081

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@211691 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 17 insertions, 0 deletions

diff --git a/include/llvm/CodeGen/MachineFrameInfo.h b/include/llvm/CodeGen/MachineFrameInfo.h
index bd0ea11911..c51f8fe03b 100644
--- a/include/llvm/CodeGen/MachineFrameInfo.h
+++ b/include/llvm/CodeGen/MachineFrameInfo.h
@@ -484,6 +484,9 @@ public:
   ///
   int CreateFixedObject(uint64_t Size, int64_t SPOffset, bool Immutable);
 
+  /// CreateFixedSpillStackObject - Create a spill slot at a fixed location
+  /// on the stack.  Returns an index with a negative value.
+  int CreateFixedSpillStackObject(uint64_t Size, int64_t SPOffset);
 
   /// isFixedObjectIndex - Returns true if the specified index corresponds to a
   /// fixed stack object.
diff --git a/include/llvm/MC/MCAsmInfo.h b/include/llvm/MC/MCAsmInfo.h
index 4c0624521d..764c1cb8ce 100644
--- a/include/llvm/MC/MCAsmInfo.h
+++ b/include/llvm/MC/MCAsmInfo.h
@@ -481,6 +481,7 @@ public:
   bool isExceptionHandlingDwarf() const {
     return (ExceptionsType == ExceptionHandling::DwarfCFI ||
             ExceptionsType == ExceptionHandling::ARM ||
+            // Win64 handler data still uses DWARF LSDA encoding.
             ExceptionsType == ExceptionHandling::Win64);
   }
   bool doesDwarfUseRelocationsAcrossSections() const {
diff --git a/include/llvm/Target/TargetFrameLowering.h b/include/llvm/Target/TargetFrameLowering.h
index 7c42e23a11..bfddd06017 100644
--- a/include/llvm/Target/TargetFrameLowering.h
+++ b/include/llvm/Target/TargetFrameLowering.h
@@ -93,6 +93,19 @@ public:
   /// stack pointer.
   virtual bool isFPCloseToIncomingSP() const { return true; }
 
+  /// assignCalleeSavedSpillSlots - Allows target to override spill slot
+  /// assignment logic.  If implemented, assignCalleeSavedSpillSlots() should
+  /// assign frame slots to all CSI entries and return true.  If this method
+  /// returns false, spill slots will be assigned using generic implementation.
+  /// assignCalleeSavedSpillSlots() may add, delete or rearrange elements of
+  /// CSI.
+  virtual bool
+  assignCalleeSavedSpillSlots(MachineFunction &MF,
+                              const TargetRegisterInfo *TRI,
+                              std::vector<CalleeSavedInfo> &CSI) const {
+    return false;
+  }
+
   /// getCalleeSavedSpillSlots - This method returns a pointer to an array of
   /// pairs, that contains an entry for each callee saved register that must be
   /// spilled to a particular stack location if it is spilled.