Long live the exception handling!

This patch fills the last necessary bits to enable exceptions
handling in LLVM. Currently only on x86-32/linux.

In fact, this patch adds necessary intrinsics (and their lowering) which
represent really weird target-specific gcc builtins used inside unwinder.

After corresponding llvm-gcc patch will land (easy) exceptions should be
more or less workable. However, exceptions handling support should not be 
thought as 'finished': I expect many small and not so small glitches
everywhere.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@39855 91177308-0d34-0410-b5e6-96231b3b80d8

4 files changed, 32 insertions, 2 deletions

diff --git a/include/llvm/CodeGen/MachineModuleInfo.h b/include/llvm/CodeGen/MachineModuleInfo.h
index 1f9decf..778b75c 100644
--- a/include/llvm/CodeGen/MachineModuleInfo.h
+++ b/include/llvm/CodeGen/MachineModuleInfo.h
@@ -1030,6 +1030,9 @@ private:
   // Personalities - Vector of all personality functions ever seen. Used to emit
   // common EH frames.
   std::vector<Function *> Personalities;
+
+  bool CallsEHReturn;
+  bool CallsUnwindInit;
 public:
   static char ID; // Pass identification, replacement for typeid
 
@@ -1072,6 +1075,12 @@ public:
   /// needsFrameInfo - Returns true if we need to gather callee-saved register
   /// move info for the frame.
   bool needsFrameInfo() const;
+
+  bool callsEHReturn() const { return CallsEHReturn; }
+  void setCallsEHReturn(bool b) { CallsEHReturn = b; }
+
+  bool callsUnwindInit() const { return CallsUnwindInit; }
+  void setCallsUnwindInit(bool b) { CallsUnwindInit = b; }
   
   /// NextLabelID - Return the next unique label id.
   ///
diff --git a/include/llvm/CodeGen/SelectionDAGNodes.h b/include/llvm/CodeGen/SelectionDAGNodes.h
index 316b02a..c96d516 100644
--- a/include/llvm/CodeGen/SelectionDAGNodes.h
+++ b/include/llvm/CodeGen/SelectionDAGNodes.h
@@ -110,6 +110,11 @@ namespace ISD {
     // to the current function's frame or return address, an index of one to the
     // parent's frame or return address, and so on.
     FRAMEADDR, RETURNADDR,
+
+    // FRAME_TO_ARGS_OFFSET - This node represents offset from frame pointer to
+    // first (possible) on-stack argument. This is needed for correct stack
+    // adjustment during unwind.
+    FRAME_TO_ARGS_OFFSET,
     
     // RESULT, OUTCHAIN = EXCEPTIONADDR(INCHAIN) - This node represents the
     // address of the exception block on entry to an landing pad block.
@@ -119,6 +124,12 @@ namespace ISD {
     // the selection index of the exception thrown.
     EHSELECTION,
 
+    // OUTCHAIN = EH_RETURN(INCHAIN, OFFSET, HANDLER) - This node represents
+    // 'eh_return' gcc dwarf builtin, which is used to return from
+    // exception. The general meaning is: adjust stack by OFFSET and pass
+    // execution to HANDLER. Many platform-related details also :)
+    EH_RETURN,
+
     // TargetConstant* - Like Constant*, but the DAG does not do any folding or
     // simplification of the constant.
     TargetConstant,
diff --git a/include/llvm/Intrinsics.td b/include/llvm/Intrinsics.td
index df3afde..e5bb2f6 100644
--- a/include/llvm/Intrinsics.td
+++ b/include/llvm/Intrinsics.td
@@ -233,6 +233,14 @@ def int_eh_selector   : Intrinsic<[llvm_i32_ty, llvm_ptr_ty, llvm_ptr_ty,
                                                 llvm_vararg_ty]>;
 def int_eh_typeid_for : Intrinsic<[llvm_i32_ty, llvm_ptr_ty]>;
 
+def int_eh_return     : Intrinsic<[llvm_void_ty, llvm_i32_ty, llvm_ptr_ty]>,
+                        GCCBuiltin<"__builtin_eh_return">;
+
+def int_eh_unwind_init: Intrinsic<[llvm_void_ty]>,
+                        GCCBuiltin<"__builtin_unwind_init">;
+
+def int_eh_dwarf_cfa  : Intrinsic<[llvm_ptr_ty, llvm_i32_ty]>;
+
 //===---------------- Generic Variable Attribute Intrinsics----------------===//
 //
 def int_var_annotation : Intrinsic<[llvm_void_ty, llvm_ptr_ty, llvm_ptr_ty,
diff --git a/include/llvm/Target/MRegisterInfo.h b/include/llvm/Target/MRegisterInfo.h
index ecfe1ec..d2b76b8 100644
--- a/include/llvm/Target/MRegisterInfo.h
+++ b/include/llvm/Target/MRegisterInfo.h
@@ -396,12 +396,14 @@ public:
   /// callee saved registers on this target. The register should be in the
   /// order of desired callee-save stack frame offset. The first register is
   /// closed to the incoming stack pointer if stack grows down, and vice versa.
-  virtual const unsigned* getCalleeSavedRegs() const = 0;
+  virtual const unsigned* getCalleeSavedRegs(const MachineFunction *MF = 0)
+                                                                      const = 0;
 
   /// getCalleeSavedRegClasses - Return a null-terminated list of the preferred
   /// register classes to spill each callee saved register with.  The order and
   /// length of this list match the getCalleeSaveRegs() list.
-  virtual const TargetRegisterClass* const *getCalleeSavedRegClasses() const =0;
+  virtual const TargetRegisterClass* const *getCalleeSavedRegClasses(
+                                            const MachineFunction *MF) const =0;
 
   /// getReservedRegs - Returns a bitset indexed by physical register number
   /// indicating if a register is a special register that has particular uses and