1 files changed, 139 insertions, 0 deletions
diff --git a/lib/Target/X86/X86FloatingPointRegKill.cpp b/lib/Target/X86/X86FloatingPointRegKill.cpp
new file mode 100644
index 0000000..009846e
--- /dev/null
+++ b/lib/Target/X86/X86FloatingPointRegKill.cpp
@@ -0,0 +1,139 @@
+//===-- X86FloatingPoint.cpp - FP_REG_KILL inserter -----------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines the pass which inserts FP_REG_KILL instructions.
+//
+//===----------------------------------------------------------------------===//
+
+#define DEBUG_TYPE "x86-codegen"
+#include "X86.h"
+#include "X86InstrInfo.h"
+#include "X86Subtarget.h"
+#include "llvm/Instructions.h"
+#include "llvm/CodeGen/MachineFunctionPass.h"
+#include "llvm/CodeGen/MachineInstrBuilder.h"
+#include "llvm/CodeGen/MachineRegisterInfo.h"
+#include "llvm/CodeGen/Passes.h"
+#include "llvm/Target/TargetMachine.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/Compiler.h"
+#include "llvm/Support/CFG.h"
+#include "llvm/ADT/Statistic.h"
+using namespace llvm;
+
+STATISTIC(NumFPKill, "Number of FP_REG_KILL instructions added");
+
+namespace {
+  struct VISIBILITY_HIDDEN FPRegKiller : public MachineFunctionPass {
+    static char ID;
+    FPRegKiller() : MachineFunctionPass(&ID) {}
+
+    virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+      AU.addPreservedID(MachineLoopInfoID);
+      AU.addPreservedID(MachineDominatorsID);
+      MachineFunctionPass::getAnalysisUsage(AU);
+    }
+
+    virtual bool runOnMachineFunction(MachineFunction &MF);
+
+    virtual const char *getPassName() const { return "X86 FP_REG_KILL inserter"; }
+  };
+  char FPRegKiller::ID = 0;
+}
+
+FunctionPass *llvm::createX87FPRegKillInserterPass() { return new FPRegKiller(); }
+
+bool FPRegKiller::runOnMachineFunction(MachineFunction &MF) {
+  // If we are emitting FP stack code, scan the basic block to determine if this
+  // block defines any FP values.  If so, put an FP_REG_KILL instruction before
+  // the terminator of the block.
+
+  // Note that FP stack instructions are used in all modes for long double,
+  // so we always need to do this check.
+  // Also note that it's possible for an FP stack register to be live across
+  // an instruction that produces multiple basic blocks (SSE CMOV) so we
+  // must check all the generated basic blocks.
+
+  // Scan all of the machine instructions in these MBBs, checking for FP
+  // stores.  (RFP32 and RFP64 will not exist in SSE mode, but RFP80 might.)
+
+  // Fast-path: If nothing is using the x87 registers, we don't need to do
+  // any scanning.
+  MachineRegisterInfo &MRI = MF.getRegInfo();
+  if (MRI.getRegClassVirtRegs(X86::RFP80RegisterClass).empty() &&
+      MRI.getRegClassVirtRegs(X86::RFP64RegisterClass).empty() &&
+      MRI.getRegClassVirtRegs(X86::RFP32RegisterClass).empty())
+    return false;
+
+  bool Changed = false;
+  const X86Subtarget &Subtarget = MF.getTarget().getSubtarget<X86Subtarget>();
+  MachineFunction::iterator MBBI = MF.begin();
+  MachineFunction::iterator EndMBB = MF.end();
+  for (; MBBI != EndMBB; ++MBBI) {
+    MachineBasicBlock *MBB = MBBI;
+    
+    // If this block returns, ignore it.  We don't want to insert an FP_REG_KILL
+    // before the return.
+    if (!MBB->empty()) {
+      MachineBasicBlock::iterator EndI = MBB->end();
+      --EndI;
+      if (EndI->getDesc().isReturn())
+        continue;
+    }
+    
+    bool ContainsFPCode = false;
+    for (MachineBasicBlock::iterator I = MBB->begin(), E = MBB->end();
+         !ContainsFPCode && I != E; ++I) {
+      if (I->getNumOperands() != 0 && I->getOperand(0).isReg()) {
+        const TargetRegisterClass *clas;
+        for (unsigned op = 0, e = I->getNumOperands(); op != e; ++op) {
+          if (I->getOperand(op).isReg() && I->getOperand(op).isDef() &&
+            TargetRegisterInfo::isVirtualRegister(I->getOperand(op).getReg()) &&
+              ((clas = MRI.getRegClass(I->getOperand(op).getReg())) == 
+                 X86::RFP32RegisterClass ||
+               clas == X86::RFP64RegisterClass ||
+               clas == X86::RFP80RegisterClass)) {
+            ContainsFPCode = true;
+            break;
+          }
+        }
+      }
+    }
+    // Check PHI nodes in successor blocks.  These PHI's will be lowered to have
+    // a copy of the input value in this block.  In SSE mode, we only care about
+    // 80-bit values.
+    if (!ContainsFPCode) {
+      // Final check, check LLVM BB's that are successors to the LLVM BB
+      // corresponding to BB for FP PHI nodes.
+      const BasicBlock *LLVMBB = MBB->getBasicBlock();
+      const PHINode *PN;
+      for (succ_const_iterator SI = succ_begin(LLVMBB), E = succ_end(LLVMBB);
+           !ContainsFPCode && SI != E; ++SI) {
+        for (BasicBlock::const_iterator II = SI->begin();
+             (PN = dyn_cast<PHINode>(II)); ++II) {
+          if (PN->getType()==Type::X86_FP80Ty ||
+              (!Subtarget.hasSSE1() && PN->getType()->isFloatingPoint()) ||
+              (!Subtarget.hasSSE2() && PN->getType()==Type::DoubleTy)) {
+            ContainsFPCode = true;
+            break;
+          }
+        }
+      }
+    }
+    // Finally, if we found any FP code, emit the FP_REG_KILL instruction.
+    if (ContainsFPCode) {
+      BuildMI(*MBB, MBBI->getFirstTerminator(), DebugLoc::getUnknownLoc(),
+              MF.getTarget().getInstrInfo()->get(X86::FP_REG_KILL));
+      ++NumFPKill;
+      Changed = true;
+    }
+  }
+
+  return Changed;
+}