[PowerPC] Support the (old) cntlz instruction alias

[oota-llvm.git] / lib / Target / AArch64 / AArch64A53Fix835769.cpp

diff --git a/lib/Target/AArch64/AArch64A53Fix835769.cpp b/lib/Target/AArch64/AArch64A53Fix835769.cpp
index 0fde69b1ae3ee10f0edad45010bb959c13bbbee6..dd401c6c9c3ad7ee058f4688e86960076b5a6793 100644 (file)
--- a/lib/Target/AArch64/AArch64A53Fix835769.cpp
+++ b/lib/Target/AArch64/AArch64A53Fix835769.cpp
@@ -16,8 +16,6 @@
 //===----------------------------------------------------------------------===//
 
 #include "AArch64.h"
-#include "AArch64InstrInfo.h"
-#include "AArch64Subtarget.h"
 #include "llvm/ADT/Statistic.h"
 #include "llvm/CodeGen/MachineFunction.h"
 #include "llvm/CodeGen/MachineFunctionPass.h"
@@ -26,6 +24,7 @@
 #include "llvm/CodeGen/MachineRegisterInfo.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Debug.h"
+#include "llvm/Target/TargetInstrInfo.h"
 
 using namespace llvm;
 
@@ -79,7 +78,7 @@ static bool isSecondInstructionInSequence(MachineInstr *MI) {
 
 namespace {
 class AArch64A53Fix835769 : public MachineFunctionPass {
-  const AArch64InstrInfo *TII;
+  const TargetInstrInfo *TII;
 
 public:
   static char ID;
@@ -107,36 +106,32 @@ char AArch64A53Fix835769::ID = 0;
 
 bool
 AArch64A53Fix835769::runOnMachineFunction(MachineFunction &F) {
-  const TargetMachine &TM = F.getTarget();
-
-  bool Changed = false;
   DEBUG(dbgs() << "***** AArch64A53Fix835769 *****\n");
-
-  TII = TM.getSubtarget<AArch64Subtarget>().getInstrInfo();
+  bool Changed = false;
+  TII = F.getSubtarget().getInstrInfo();
 
   for (auto &MBB : F) {
     Changed |= runOnBasicBlock(MBB);
   }
-
   return Changed;
 }
 
 // Return the block that was fallen through to get to MBB, if any,
 // otherwise nullptr.
-static MachineBasicBlock *getBBFallenThrough(MachineBasicBlock &MBB,
+static MachineBasicBlock *getBBFallenThrough(MachineBasicBlock *MBB,
                                              const TargetInstrInfo *TII) {
   // Get the previous machine basic block in the function.
-  MachineFunction::iterator MBBI = MBB;
+  MachineFunction::iterator MBBI = *MBB;
 
   // Can't go off top of function.
-  if (MBBI == MBB.getParent()->begin())
+  if (MBBI == MBB->getParent()->begin())
     return nullptr;
 
   MachineBasicBlock *TBB = nullptr, *FBB = nullptr;
   SmallVector<MachineOperand, 2> Cond;
 
   MachineBasicBlock *PrevBB = std::prev(MBBI);
-  for (MachineBasicBlock *S : MBB.predecessors())
+  for (MachineBasicBlock *S : MBB->predecessors())
     if (S == PrevBB && !TII->AnalyzeBranch(*PrevBB, TBB, FBB, Cond) &&
         !TBB && !FBB)
       return S;
@@ -144,13 +139,25 @@ static MachineBasicBlock *getBBFallenThrough(MachineBasicBlock &MBB,
   return nullptr;
 }
 
-static MachineInstr *getLastNonPseudo(MachineBasicBlock *MBB) {
-  for (auto I = MBB->rbegin(), E = MBB->rend(); I != E; ++I) {
-    if (!I->isPseudo())
-      return &*I;
+// Iterate through fallen through blocks trying to find a previous non-pseudo if
+// there is one, otherwise return nullptr. Only look for instructions in
+// previous blocks, not the current block, since we only use this to look at
+// previous blocks.
+static MachineInstr *getLastNonPseudo(MachineBasicBlock &MBB,
+                                      const TargetInstrInfo *TII) {
+  MachineBasicBlock *FMBB = &MBB;
+
+  // If there is no non-pseudo in the current block, loop back around and try
+  // the previous block (if there is one).
+  while ((FMBB = getBBFallenThrough(FMBB, TII))) {
+    for (auto I = FMBB->rbegin(), E = FMBB->rend(); I != E; ++I) {
+      if (!I->isPseudo())
+        return &*I;
+    }
   }
 
-  llvm_unreachable("Expected to find a non-pseudo instruction");
+  // There was no previous non-pseudo in the fallen through blocks
+  return nullptr;
 }
 
 static void insertNopBeforeInstruction(MachineBasicBlock &MBB, MachineInstr* MI,
@@ -158,12 +165,10 @@ static void insertNopBeforeInstruction(MachineBasicBlock &MBB, MachineInstr* MI,
   // If we are the first instruction of the block, put the NOP at the end of
   // the previous fallthrough block
   if (MI == &MBB.front()) {
-    MachineBasicBlock *PMBB = getBBFallenThrough(MBB, TII);
-    assert(PMBB && "Expected basic block");
-    MachineInstr *I = getLastNonPseudo(PMBB);
+    MachineInstr *I = getLastNonPseudo(MBB, TII);
     assert(I && "Expected instruction");
     DebugLoc DL = I->getDebugLoc();
-    BuildMI(PMBB, DL, TII->get(AArch64::HINT)).addImm(0);
+    BuildMI(I->getParent(), DL, TII->get(AArch64::HINT)).addImm(0);
   }
   else {
     DebugLoc DL = MI->getDebugLoc();
@@ -186,8 +191,9 @@ AArch64A53Fix835769::runOnBasicBlock(MachineBasicBlock &MBB) {
   unsigned Idx = 0;
   MachineInstr *PrevInstr = nullptr;
 
-  if (MachineBasicBlock *PMBB = getBBFallenThrough(MBB, TII))
-      PrevInstr = getLastNonPseudo(PMBB);
+  // Try and find the last non-pseudo instruction in any fallen through blocks,
+  // if there isn't one, then we use nullptr to represent that.
+  PrevInstr = getLastNonPseudo(MBB, TII);
 
   for (auto &MI : MBB) {
     MachineInstr *CurrInstr = &MI;