1 files changed, 272 insertions, 0 deletions
diff --git a/contrib/llvm/lib/Target/R600/SIShrinkInstructions.cpp b/contrib/llvm/lib/Target/R600/SIShrinkInstructions.cpp
new file mode 100644
index 0000000..51e72cd
--- /dev/null
+++ b/contrib/llvm/lib/Target/R600/SIShrinkInstructions.cpp
@@ -0,0 +1,272 @@
+//===-- SIShrinkInstructions.cpp - Shrink Instructions --------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+/// The pass tries to use the 32-bit encoding for instructions when possible.
+//===----------------------------------------------------------------------===//
+//
+
+#include "AMDGPU.h"
+#include "AMDGPUMCInstLower.h"
+#include "AMDGPUSubtarget.h"
+#include "SIInstrInfo.h"
+#include "llvm/ADT/Statistic.h"
+#include "llvm/CodeGen/MachineFunctionPass.h"
+#include "llvm/CodeGen/MachineInstrBuilder.h"
+#include "llvm/CodeGen/MachineRegisterInfo.h"
+#include "llvm/IR/Constants.h"
+#include "llvm/IR/Function.h"
+#include "llvm/IR/LLVMContext.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/raw_ostream.h"
+#include "llvm/Target/TargetMachine.h"
+
+#define DEBUG_TYPE "si-shrink-instructions"
+
+STATISTIC(NumInstructionsShrunk,
+          "Number of 64-bit instruction reduced to 32-bit.");
+STATISTIC(NumLiteralConstantsFolded,
+          "Number of literal constants folded into 32-bit instructions.");
+
+namespace llvm {
+  void initializeSIShrinkInstructionsPass(PassRegistry&);
+}
+
+using namespace llvm;
+
+namespace {
+
+class SIShrinkInstructions : public MachineFunctionPass {
+public:
+  static char ID;
+
+public:
+  SIShrinkInstructions() : MachineFunctionPass(ID) {
+  }
+
+  bool runOnMachineFunction(MachineFunction &MF) override;
+
+  const char *getPassName() const override {
+    return "SI Shrink Instructions";
+  }
+
+  void getAnalysisUsage(AnalysisUsage &AU) const override {
+    AU.setPreservesCFG();
+    MachineFunctionPass::getAnalysisUsage(AU);
+  }
+};
+
+} // End anonymous namespace.
+
+INITIALIZE_PASS_BEGIN(SIShrinkInstructions, DEBUG_TYPE,
+                      "SI Lower il Copies", false, false)
+INITIALIZE_PASS_END(SIShrinkInstructions, DEBUG_TYPE,
+                    "SI Lower il Copies", false, false)
+
+char SIShrinkInstructions::ID = 0;
+
+FunctionPass *llvm::createSIShrinkInstructionsPass() {
+  return new SIShrinkInstructions();
+}
+
+static bool isVGPR(const MachineOperand *MO, const SIRegisterInfo &TRI,
+                   const MachineRegisterInfo &MRI) {
+  if (!MO->isReg())
+    return false;
+
+  if (TargetRegisterInfo::isVirtualRegister(MO->getReg()))
+    return TRI.hasVGPRs(MRI.getRegClass(MO->getReg()));
+
+  return TRI.hasVGPRs(TRI.getPhysRegClass(MO->getReg()));
+}
+
+static bool canShrink(MachineInstr &MI, const SIInstrInfo *TII,
+                      const SIRegisterInfo &TRI,
+                      const MachineRegisterInfo &MRI) {
+
+  const MachineOperand *Src2 = TII->getNamedOperand(MI, AMDGPU::OpName::src2);
+  // Can't shrink instruction with three operands.
+  // FIXME: v_cndmask_b32 has 3 operands and is shrinkable, but we need to add
+  // a special case for it.  It can only be shrunk if the third operand
+  // is vcc.  We should handle this the same way we handle vopc, by addding
+  // a register allocation hint pre-regalloc and then do the shrining
+  // post-regalloc.
+  if (Src2)
+    return false;
+
+  const MachineOperand *Src1 = TII->getNamedOperand(MI, AMDGPU::OpName::src1);
+  const MachineOperand *Src1Mod =
+      TII->getNamedOperand(MI, AMDGPU::OpName::src1_modifiers);
+
+  if (Src1 && (!isVGPR(Src1, TRI, MRI) || (Src1Mod && Src1Mod->getImm() != 0)))
+    return false;
+
+  // We don't need to check src0, all input types are legal, so just make sure
+  // src0 isn't using any modifiers.
+  if (TII->hasModifiersSet(MI, AMDGPU::OpName::src0_modifiers))
+    return false;
+
+  // Check output modifiers
+  if (TII->hasModifiersSet(MI, AMDGPU::OpName::omod))
+    return false;
+
+  if (TII->hasModifiersSet(MI, AMDGPU::OpName::clamp))
+    return false;
+
+  return true;
+}
+
+/// \brief This function checks \p MI for operands defined by a move immediate
+/// instruction and then folds the literal constant into the instruction if it
+/// can.  This function assumes that \p MI is a VOP1, VOP2, or VOPC instruction
+/// and will only fold literal constants if we are still in SSA.
+static void foldImmediates(MachineInstr &MI, const SIInstrInfo *TII,
+                           MachineRegisterInfo &MRI, bool TryToCommute = true) {
+
+  if (!MRI.isSSA())
+    return;
+
+  assert(TII->isVOP1(MI.getOpcode()) || TII->isVOP2(MI.getOpcode()) ||
+         TII->isVOPC(MI.getOpcode()));
+
+  const SIRegisterInfo &TRI = TII->getRegisterInfo();
+  int Src0Idx = AMDGPU::getNamedOperandIdx(MI.getOpcode(), AMDGPU::OpName::src0);
+  MachineOperand &Src0 = MI.getOperand(Src0Idx);
+
+  // Only one literal constant is allowed per instruction, so if src0 is a
+  // literal constant then we can't do any folding.
+  if (Src0.isImm() &&
+      TII->isLiteralConstant(Src0, TII->getOpSize(MI, Src0Idx)))
+    return;
+
+  // Literal constants and SGPRs can only be used in Src0, so if Src0 is an
+  // SGPR, we cannot commute the instruction, so we can't fold any literal
+  // constants.
+  if (Src0.isReg() && !isVGPR(&Src0, TRI, MRI))
+    return;
+
+  // Try to fold Src0
+  if (Src0.isReg()) {
+    unsigned Reg = Src0.getReg();
+    MachineInstr *Def = MRI.getUniqueVRegDef(Reg);
+    if (Def && Def->isMoveImmediate()) {
+      MachineOperand &MovSrc = Def->getOperand(1);
+      bool ConstantFolded = false;
+
+      if (MovSrc.isImm() && isUInt<32>(MovSrc.getImm())) {
+        Src0.ChangeToImmediate(MovSrc.getImm());
+        ConstantFolded = true;
+      }
+      if (ConstantFolded) {
+        if (MRI.use_empty(Reg))
+          Def->eraseFromParent();
+        ++NumLiteralConstantsFolded;
+        return;
+      }
+    }
+  }
+
+  // We have failed to fold src0, so commute the instruction and try again.
+  if (TryToCommute && MI.isCommutable() && TII->commuteInstruction(&MI))
+    foldImmediates(MI, TII, MRI, false);
+
+}
+
+bool SIShrinkInstructions::runOnMachineFunction(MachineFunction &MF) {
+  MachineRegisterInfo &MRI = MF.getRegInfo();
+  const SIInstrInfo *TII =
+      static_cast<const SIInstrInfo *>(MF.getSubtarget().getInstrInfo());
+  const SIRegisterInfo &TRI = TII->getRegisterInfo();
+  std::vector<unsigned> I1Defs;
+
+  for (MachineFunction::iterator BI = MF.begin(), BE = MF.end();
+                                                  BI != BE; ++BI) {
+
+    MachineBasicBlock &MBB = *BI;
+    MachineBasicBlock::iterator I, Next;
+    for (I = MBB.begin(); I != MBB.end(); I = Next) {
+      Next = std::next(I);
+      MachineInstr &MI = *I;
+
+      // Try to use S_MOVK_I32, which will save 4 bytes for small immediates.
+      if (MI.getOpcode() == AMDGPU::S_MOV_B32) {
+        const MachineOperand &Src = MI.getOperand(1);
+
+        if (Src.isImm()) {
+          if (isInt<16>(Src.getImm()) && !TII->isInlineConstant(Src, 4))
+            MI.setDesc(TII->get(AMDGPU::S_MOVK_I32));
+        }
+
+        continue;
+      }
+
+      if (!TII->hasVALU32BitEncoding(MI.getOpcode()))
+        continue;
+
+      if (!canShrink(MI, TII, TRI, MRI)) {
+        // Try commuting the instruction and see if that enables us to shrink
+        // it.
+        if (!MI.isCommutable() || !TII->commuteInstruction(&MI) ||
+            !canShrink(MI, TII, TRI, MRI))
+          continue;
+      }
+
+      // getVOPe32 could be -1 here if we started with an instruction that had
+      // a 32-bit encoding and then commuted it to an instruction that did not.
+      if (!TII->hasVALU32BitEncoding(MI.getOpcode()))
+        continue;
+
+      int Op32 = AMDGPU::getVOPe32(MI.getOpcode());
+
+      if (TII->isVOPC(Op32)) {
+        unsigned DstReg = MI.getOperand(0).getReg();
+        if (TargetRegisterInfo::isVirtualRegister(DstReg)) {
+          // VOPC instructions can only write to the VCC register.  We can't
+          // force them to use VCC here, because the register allocator has
+          // trouble with sequences like this, which cause the allocator to run
+          // out of registers if vreg0 and vreg1 belong to the VCCReg register
+          // class:
+          // vreg0 = VOPC;
+          // vreg1 = VOPC;
+          // S_AND_B64 vreg0, vreg1
+          //
+          // So, instead of forcing the instruction to write to VCC, we provide
+          // a hint to the register allocator to use VCC and then we we will run
+          // this pass again after RA and shrink it if it outputs to VCC.
+          MRI.setRegAllocationHint(MI.getOperand(0).getReg(), 0, AMDGPU::VCC);
+          continue;
+        }
+        if (DstReg != AMDGPU::VCC)
+          continue;
+      }
+
+      // We can shrink this instruction
+      DEBUG(dbgs() << "Shrinking "; MI.dump(); dbgs() << '\n';);
+
+      MachineInstrBuilder Inst32 =
+          BuildMI(MBB, I, MI.getDebugLoc(), TII->get(Op32));
+
+      // dst
+      Inst32.addOperand(MI.getOperand(0));
+
+      Inst32.addOperand(*TII->getNamedOperand(MI, AMDGPU::OpName::src0));
+
+      const MachineOperand *Src1 =
+          TII->getNamedOperand(MI, AMDGPU::OpName::src1);
+      if (Src1)
+        Inst32.addOperand(*Src1);
+
+      ++NumInstructionsShrunk;
+      MI.eraseFromParent();
+
+      foldImmediates(*Inst32, TII, MRI);
+      DEBUG(dbgs() << "e32 MI = " << *Inst32 << '\n');
+
+
+    }
+  }
+  return false;
+}