XCore target: Fix eliminateFrameIndex() to handle large frames

Large frame offsets are loaded from the ConstantPool.
Where possible, offsets are encoded using the smaller MKMSK instruction.
Large frame offsets can only be used when there is a frame-pointer.

llvm-svn: 196085

1 files changed, 18 insertions, 7 deletions

diff --git a/llvm/lib/Target/XCore/XCoreRegisterInfo.cpp b/llvm/lib/Target/XCore/XCoreRegisterInfo.cpp
index dbd2f52a5b1..607e512b3ec 100644
--- a/llvm/lib/Target/XCore/XCoreRegisterInfo.cpp
+++ b/llvm/lib/Target/XCore/XCoreRegisterInfo.cpp
@@ -16,16 +16,19 @@
 #include "XCoreMachineFunctionInfo.h"
 #include "llvm/ADT/BitVector.h"
 #include "llvm/ADT/STLExtras.h"
+#include "llvm/CodeGen/MachineConstantPool.h"
 #include "llvm/CodeGen/MachineFrameInfo.h"
 #include "llvm/CodeGen/MachineFunction.h"
 #include "llvm/CodeGen/MachineInstrBuilder.h"
 #include "llvm/CodeGen/MachineModuleInfo.h"
 #include "llvm/CodeGen/MachineRegisterInfo.h"
 #include "llvm/CodeGen/RegisterScavenging.h"
+#include "llvm/IR/Constants.h"
 #include "llvm/IR/Function.h"
 #include "llvm/IR/Type.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/MathExtras.h"
 #include "llvm/Support/raw_ostream.h"
 #include "llvm/Target/TargetFrameLowering.h"
 #include "llvm/Target/TargetInstrInfo.h"
@@ -244,14 +247,22 @@ XCoreRegisterInfo::eliminateFrameIndex(MachineBasicBlock::iterator II,
 void XCoreRegisterInfo::
 loadConstant(MachineBasicBlock &MBB, MachineBasicBlock::iterator I,
             unsigned DstReg, int64_t Value, DebugLoc dl) const {
-  // TODO use mkmsk if possible.
-  if (!isImmU16(Value)) {
-    // TODO use constant pool.
-    report_fatal_error("loadConstant value too big " + Twine(Value));
-  }
-  int Opcode = isImmU6(Value) ? XCore::LDC_ru6 : XCore::LDC_lru6;
   const TargetInstrInfo &TII = *MBB.getParent()->getTarget().getInstrInfo();
-  BuildMI(MBB, I, dl, TII.get(Opcode), DstReg).addImm(Value);
+  if (isMask_32(Value)) {
+    int N = Log2_32(Value) + 1;
+    BuildMI(MBB, I, dl, TII.get(XCore::MKMSK_rus), DstReg).addImm(N);
+  } else if (isImmU16(Value)) {
+    int Opcode = isImmU6(Value) ? XCore::LDC_ru6 : XCore::LDC_lru6;
+    BuildMI(MBB, I, dl, TII.get(Opcode), DstReg).addImm(Value);
+    return;
+  } else {
+    MachineConstantPool *ConstantPool = MBB.getParent()->getConstantPool();
+    const Constant *C = ConstantInt::get(
+        Type::getInt32Ty(MBB.getParent()->getFunction()->getContext()), Value);
+    unsigned Idx = ConstantPool->getConstantPoolIndex(C, 4);
+    BuildMI(MBB, I, dl, TII.get(XCore::LDWCP_lru6), DstReg)
+        .addConstantPoolIndex(Idx);
+  }
 }
 
 unsigned XCoreRegisterInfo::getFrameRegister(const MachineFunction &MF) const {