R600/SI: Implement spilling of SGPRs v5

SGPRs are spilled into VGPRs using the {READ,WRITE}LANE_B32 instructions.

v2:
  - Fix encoding of Lane Mask
  - Use correct register flags, so we don't overwrite the low dword
    when restoring multi-dword registers.

v3:
  - Register spilling seems to hang the GPU, so replace all shaders
    that need spilling with a dummy shader.

v4:
  - Fix *LANE definitions
  - Change destination reg class for 32-bit SMRD instructions

v5:
  - Remove small optimization that was crashing Serious Sam 3.

https://bugs.freedesktop.org/show_bug.cgi?id=68224
https://bugs.freedesktop.org/show_bug.cgi?id=71285

NOTE: This is a candidate for the 3.4 branch.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@195880 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Target/R600/SIMachineFunctionInfo.cpp

@@ -10,6 +10,10 @@
 
 
 #include "SIMachineFunctionInfo.h"
+#include "SIRegisterInfo.h"
+#include "llvm/CodeGen/MachineRegisterInfo.h"
+
+#define MAX_LANES 64
 
 using namespace llvm;
 
@@ -19,4 +23,33 @@ void SIMachineFunctionInfo::anchor() {}
 
 SIMachineFunctionInfo::SIMachineFunctionInfo(const MachineFunction &MF)
   : AMDGPUMachineFunction(MF),
-    PSInputAddr(0) { }
+    PSInputAddr(0),
+    SpillTracker() { }
+
+static unsigned createLaneVGPR(MachineRegisterInfo &MRI) {
+  return MRI.createVirtualRegister(&AMDGPU::VReg_32RegClass);
+}
+
+unsigned SIMachineFunctionInfo::RegSpillTracker::getNextLane(MachineRegisterInfo &MRI) {
+  if (!LaneVGPR) {
+    LaneVGPR = createLaneVGPR(MRI);
+  } else {
+    CurrentLane++;
+    if (CurrentLane == MAX_LANES) {
+      CurrentLane = 0;
+      LaneVGPR = createLaneVGPR(MRI);
+    }
+  }
+  return CurrentLane;
+}
+
+void SIMachineFunctionInfo::RegSpillTracker::addSpilledReg(unsigned FrameIndex,
+                                                           unsigned Reg,
+                                                           int Lane) {
+  SpilledRegisters[FrameIndex] = SpilledReg(Reg, Lane);
+}
+
+const SIMachineFunctionInfo::SpilledReg&
+SIMachineFunctionInfo::RegSpillTracker::getSpilledReg(unsigned FrameIndex) {
+  return SpilledRegisters[FrameIndex];
+}