[mips] Interrupt attribute support for mips32r2+.

Summary:
This patch adds support for using the "interrupt" attribute on Mips
for interrupt handling functions. At this time only mips32r2+ with the
o32 ABI with the static relocation model is supported. Unsupported
configurations will be rejected

Patch by Simon Dardis (+ clang-format & some trivial changes to follow the
LLVM coding standards by me).

Reviewers: mpf, dsanders

Subscribers: dsanders, vkalintiris, llvm-commits

Differential Revision: http://reviews.llvm.org/D10768

llvm-svn: 251286

1 files changed, 15 insertions, 1 deletions

diff --git a/llvm/lib/Target/Mips/MipsMachineFunction.h b/llvm/lib/Target/Mips/MipsMachineFunction.h
index a1b2e81..a2f6ee03 100644
--- a/llvm/lib/Target/Mips/MipsMachineFunction.h
+++ b/llvm/lib/Target/Mips/MipsMachineFunction.h
@@ -34,7 +34,7 @@ class MipsFunctionInfo : public MachineFunctionInfo {
 public:
   MipsFunctionInfo(MachineFunction &MF)
       : MF(MF), SRetReturnReg(0), GlobalBaseReg(0), Mips16SPAliasReg(0),
-        VarArgsFrameIndex(0), CallsEhReturn(false), SaveS2(false),
+        VarArgsFrameIndex(0), CallsEhReturn(false), IsISR(false), SaveS2(false),
         MoveF64ViaSpillFI(-1) {}
 
   ~MipsFunctionInfo();
@@ -70,6 +70,14 @@ public:
   /// object representing a GOT entry for an external function.
   MachinePointerInfo callPtrInfo(const char *ES);
 
+  // Functions with the "interrupt" attribute require special prologues,
+  // epilogues and additional spill slots.
+  bool isISR() const { return IsISR; }
+  void setISR() { IsISR = true; }
+  void createISRRegFI();
+  int getISRRegFI(unsigned Reg) const { return ISRDataRegFI[Reg]; }
+  bool isISRRegFI(int FI) const;
+
   /// Create a MachinePointerInfo that has a GlobalValuePseudoSourceValue object
   /// representing a GOT entry for a global function.
   MachinePointerInfo callPtrInfo(const GlobalValue *GV);
@@ -116,6 +124,12 @@ private:
   /// Frame objects for spilling eh data registers.
   int EhDataRegFI[4];
 
+  /// ISR - Whether the function is an Interrupt Service Routine.
+  bool IsISR;
+
+  /// Frame objects for spilling C0_STATUS, C0_EPC
+  int ISRDataRegFI[2];
+
   // saveS2
   bool SaveS2;