[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, 0 deletions

diff --git a/llvm/lib/Target/Mips/MipsMachineFunction.cpp b/llvm/lib/Target/Mips/MipsMachineFunction.cpp
index 839760c..c7d2738 100644
--- a/llvm/lib/Target/Mips/MipsMachineFunction.cpp
+++ b/llvm/lib/Target/Mips/MipsMachineFunction.cpp
@@ -75,11 +75,26 @@ void MipsFunctionInfo::createEhDataRegsFI() {
   }
 }
 
+void MipsFunctionInfo::createISRRegFI() {
+  // ISRs require spill slots for Status & ErrorPC Coprocessor 0 registers.
+  // The current implementation only supports Mips32r2+ not Mips64rX. Status
+  // is always 32 bits, ErrorPC is 32 or 64 bits dependant on architecture,
+  // however Mips32r2+ is the supported architecture.
+  const TargetRegisterClass *RC = &Mips::GPR32RegClass;
+
+  for (int I = 0; I < 2; ++I)
+    ISRDataRegFI[I] = MF.getFrameInfo()->CreateStackObject(
+        RC->getSize(), RC->getAlignment(), false);
+}
+
 bool MipsFunctionInfo::isEhDataRegFI(int FI) const {
   return CallsEhReturn && (FI == EhDataRegFI[0] || FI == EhDataRegFI[1]
                         || FI == EhDataRegFI[2] || FI == EhDataRegFI[3]);
 }
 
+bool MipsFunctionInfo::isISRRegFI(int FI) const {
+  return IsISR && (FI == ISRDataRegFI[0] || FI == ISRDataRegFI[1]);
+}
 MachinePointerInfo MipsFunctionInfo::callPtrInfo(const char *ES) {
   return MachinePointerInfo(MF.getPSVManager().getExternalSymbolCallEntry(ES));
 }