R600/SI: Use external symbols for scratch buffer

We were passing the scratch buffer address to the shaders via user sgprs,
but now we use external symbols and have the driver patch the shader
using reloc information.

llvm-svn: 226586

1 files changed, 51 insertions, 41 deletions

diff --git a/llvm/lib/Target/R600/SIPrepareScratchRegs.cpp b/llvm/lib/Target/R600/SIPrepareScratchRegs.cpp
index f0e7edec6b4..b7934bd9e91 100644
--- a/llvm/lib/Target/R600/SIPrepareScratchRegs.cpp
+++ b/llvm/lib/Target/R600/SIPrepareScratchRegs.cpp
@@ -29,6 +29,7 @@
 #include "llvm/IR/Function.h"
 #include "llvm/IR/LLVMContext.h"
 
+#include "llvm/Support/Debug.h"
 using namespace llvm;
 
 namespace {
@@ -84,28 +85,10 @@ bool SIPrepareScratchRegs::runOnMachineFunction(MachineFunction &MF) {
   if (!Entry->isLiveIn(ScratchOffsetPreloadReg))
     Entry->addLiveIn(ScratchOffsetPreloadReg);
 
-  // Load the scratch pointer
-  unsigned ScratchPtrReg =
-      TRI->findUnusedRegister(MRI, &AMDGPU::SGPR_64RegClass);
-  int ScratchPtrFI = -1;
-
-  if (ScratchPtrReg != AMDGPU::NoRegister) {
-    // Found an SGPR to use.
-    MRI.setPhysRegUsed(ScratchPtrReg);
-    BuildMI(*Entry, I, DL, TII->get(AMDGPU::S_MOV_B64), ScratchPtrReg)
-            .addReg(ScratchPtrPreloadReg);
-  } else {
-    // No SGPR is available, we must spill.
-    ScratchPtrFI = FrameInfo->CreateSpillStackObject(8, 4);
-    BuildMI(*Entry, I, DL, TII->get(AMDGPU::SI_SPILL_S64_SAVE))
-            .addReg(ScratchPtrPreloadReg)
-            .addFrameIndex(ScratchPtrFI);
-  }
-
   // Load the scratch offset.
   unsigned ScratchOffsetReg =
       TRI->findUnusedRegister(MRI, &AMDGPU::SGPR_32RegClass);
-  int ScratchOffsetFI = ~0;
+  int ScratchOffsetFI = -1;
 
   if (ScratchOffsetReg != AMDGPU::NoRegister) {
     // Found an SGPR to use
@@ -125,22 +108,26 @@ bool SIPrepareScratchRegs::runOnMachineFunction(MachineFunction &MF) {
   // add them to all the SI_SPILL_V* instructions.
 
   RegScavenger RS;
-  bool UseRegScavenger =
-      (ScratchPtrReg == AMDGPU::NoRegister ||
-      ScratchOffsetReg == AMDGPU::NoRegister);
+  unsigned ScratchRsrcFI = FrameInfo->CreateSpillStackObject(16, 4);
+  RS.addScavengingFrameIndex(ScratchRsrcFI);
+
   for (MachineFunction::iterator BI = MF.begin(), BE = MF.end();
        BI != BE; ++BI) {
 
     MachineBasicBlock &MBB = *BI;
-    if (UseRegScavenger)
-      RS.enterBasicBlock(&MBB);
+    // Add the scratch offset reg as a live-in so that the register scavenger
+    // doesn't re-use it.
+    if (!MBB.isLiveIn(ScratchOffsetReg))
+      MBB.addLiveIn(ScratchOffsetReg);
+    RS.enterBasicBlock(&MBB);
 
     for (MachineBasicBlock::iterator I = MBB.begin(), E = MBB.end();
          I != E; ++I) {
       MachineInstr &MI = *I;
+      RS.forward(I);
       DebugLoc DL = MI.getDebugLoc();
       switch(MI.getOpcode()) {
-        default: break;;
+        default: break;
         case AMDGPU::SI_SPILL_V512_SAVE:
         case AMDGPU::SI_SPILL_V256_SAVE:
         case AMDGPU::SI_SPILL_V128_SAVE:
@@ -153,18 +140,35 @@ bool SIPrepareScratchRegs::runOnMachineFunction(MachineFunction &MF) {
         case AMDGPU::SI_SPILL_V256_RESTORE:
         case AMDGPU::SI_SPILL_V512_RESTORE:
 
-          // Scratch Pointer
-          if (ScratchPtrReg == AMDGPU::NoRegister) {
-            ScratchPtrReg = RS.scavengeRegister(&AMDGPU::SGPR_64RegClass, 0);
-            BuildMI(MBB, I, DL, TII->get(AMDGPU::SI_SPILL_S64_RESTORE),
-                    ScratchPtrReg)
-                    .addFrameIndex(ScratchPtrFI)
-                    .addReg(AMDGPU::NoRegister)
-                    .addReg(AMDGPU::NoRegister);
-          } else if (!MBB.isLiveIn(ScratchPtrReg)) {
-            MBB.addLiveIn(ScratchPtrReg);
-          }
+          // Scratch resource
+          unsigned ScratchRsrcReg =
+              RS.scavengeRegister(&AMDGPU::SReg_128RegClass, 0);
+
+          uint64_t Rsrc = AMDGPU::RSRC_DATA_FORMAT | AMDGPU::RSRC_TID_ENABLE |
+                          0xffffffff; // Size
+
+          unsigned Rsrc0 = TRI->getSubReg(ScratchRsrcReg, AMDGPU::sub0);
+          unsigned Rsrc1 = TRI->getSubReg(ScratchRsrcReg, AMDGPU::sub1);
+          unsigned Rsrc2 = TRI->getSubReg(ScratchRsrcReg, AMDGPU::sub2);
+          unsigned Rsrc3 = TRI->getSubReg(ScratchRsrcReg, AMDGPU::sub3);
+
+          BuildMI(MBB, I, DL, TII->get(AMDGPU::S_MOV_B32), Rsrc0)
+                  .addExternalSymbol("SCRATCH_RSRC_DWORD0")
+                  .addReg(ScratchRsrcReg, RegState::ImplicitDefine);
+
+          BuildMI(MBB, I, DL, TII->get(AMDGPU::S_MOV_B32), Rsrc1)
+                  .addExternalSymbol("SCRATCH_RSRC_DWORD1")
+                  .addReg(ScratchRsrcReg, RegState::ImplicitDefine);
+
+          BuildMI(MBB, I, DL, TII->get(AMDGPU::S_MOV_B32), Rsrc2)
+                  .addImm(Rsrc & 0xffffffff)
+                  .addReg(ScratchRsrcReg, RegState::ImplicitDefine);
+
+          BuildMI(MBB, I, DL, TII->get(AMDGPU::S_MOV_B32), Rsrc3)
+                  .addImm(Rsrc >> 32)
+                  .addReg(ScratchRsrcReg, RegState::ImplicitDefine);
 
+          // Scratch Offset
           if (ScratchOffsetReg == AMDGPU::NoRegister) {
             ScratchOffsetReg = RS.scavengeRegister(&AMDGPU::SGPR_32RegClass, 0);
             BuildMI(MBB, I, DL, TII->get(AMDGPU::SI_SPILL_S32_RESTORE),
@@ -176,20 +180,26 @@ bool SIPrepareScratchRegs::runOnMachineFunction(MachineFunction &MF) {
             MBB.addLiveIn(ScratchOffsetReg);
           }
 
-          if (ScratchPtrReg == AMDGPU::NoRegister ||
+          if (ScratchRsrcReg == AMDGPU::NoRegister ||
               ScratchOffsetReg == AMDGPU::NoRegister) {
             LLVMContext &Ctx = MF.getFunction()->getContext();
             Ctx.emitError("ran out of SGPRs for spilling VGPRs");
-            ScratchPtrReg = AMDGPU::SGPR0;
+            ScratchRsrcReg = AMDGPU::SGPR0;
             ScratchOffsetReg = AMDGPU::SGPR0;
           }
-          MI.getOperand(2).setReg(ScratchPtrReg);
+          MI.getOperand(2).setReg(ScratchRsrcReg);
+          MI.getOperand(2).setIsKill(true);
+          MI.getOperand(2).setIsUndef(false);
           MI.getOperand(3).setReg(ScratchOffsetReg);
+          MI.getOperand(3).setIsUndef(false);
+          MI.addOperand(MachineOperand::CreateReg(Rsrc0, false, true, true));
+          MI.addOperand(MachineOperand::CreateReg(Rsrc1, false, true, true));
+          MI.addOperand(MachineOperand::CreateReg(Rsrc2, false, true, true));
+          MI.addOperand(MachineOperand::CreateReg(Rsrc3, false, true, true));
 
+          MI.dump();
           break;
       }
-      if (UseRegScavenger)
-        RS.forward();
     }
   }
   return true;