Revert r97766. It's deleting a tag.

llvm-svn: 97768

1 files changed, 13 insertions, 52 deletions

diff --git a/llvm/lib/Target/X86/X86InstrInfo.cpp b/llvm/lib/Target/X86/X86InstrInfo.cpp
index 0d3b54fe8e2..39bda04b4d1 100644
--- a/llvm/lib/Target/X86/X86InstrInfo.cpp
+++ b/llvm/lib/Target/X86/X86InstrInfo.cpp
@@ -1786,7 +1786,6 @@ X86InstrInfo::InsertBranch(MachineBasicBlock &MBB, MachineBasicBlock *TBB,
                            const SmallVectorImpl<MachineOperand> &Cond) const {
   // FIXME this should probably have a DebugLoc operand
   DebugLoc dl = DebugLoc::getUnknownLoc();
-
   // Shouldn't be a fall through.
   assert(TBB && "InsertBranch must not be told to insert a fallthrough");
   assert((Cond.size() == 1 || Cond.size() == 0) &&
@@ -1800,72 +1799,34 @@ X86InstrInfo::InsertBranch(MachineBasicBlock &MBB, MachineBasicBlock *TBB,
   }
 
   // Conditional branch.
-  const MachineBasicBlock *NextBB = next(&MBB);
   unsigned Count = 0;
   X86::CondCode CC = (X86::CondCode)Cond[0].getImm();
-
-  // In a two-way conditional branch, if the fall-through block is the
-  // "false" branch of the conditional jumps, we can cut out the
-  // unconditional jump by rearranging the conditional jumps. This saves a
-  // few bytes and improves performance. I.e., for COND_NE_OR_P:
-  //
-  //     JNE L1
-  //     JP  L1
-  //     JMP L2
-  // L1:
-  //     ...
-  // L2:
-  //     ...
-  //
-  // to:
-  // 
-  //     JP  L1
-  //     JE  L2
-  // L1:
-  //     ...
-  // L2:
-  //     ...
-  //
-  // Similarly for COND_NP_OR_E.
   switch (CC) {
-  default:
-    BuildMI(&MBB, dl, get(GetCondBranchFromCond(CC))).addMBB(TBB);
-    ++Count;
-    break;
   case X86::COND_NP_OR_E:
     // Synthesize NP_OR_E with two branches.
-    if (FBB && FBB == NextBB) {
-      BuildMI(&MBB, dl, get(X86::JNP_4)).addMBB(TBB);
-      BuildMI(&MBB, dl, get(X86::JNE_4)).addMBB(FBB);
-      FBB = 0;
-    } else {
-      BuildMI(&MBB, dl, get(X86::JNP_4)).addMBB(TBB);
-      BuildMI(&MBB, dl, get(X86::JE_4)).addMBB(TBB);
-    }
-
-    Count += 2;
+    BuildMI(&MBB, dl, get(X86::JNP_4)).addMBB(TBB);
+    ++Count;
+    BuildMI(&MBB, dl, get(X86::JE_4)).addMBB(TBB);
+    ++Count;
     break;
   case X86::COND_NE_OR_P:
     // Synthesize NE_OR_P with two branches.
-    if (FBB && FBB == NextBB) {
-      BuildMI(&MBB, dl, get(X86::JP_4)).addMBB(TBB);
-      BuildMI(&MBB, dl, get(X86::JE_4)).addMBB(FBB);
-      FBB = 0;
-    } else {
-      BuildMI(&MBB, dl, get(X86::JNE_4)).addMBB(TBB);
-      BuildMI(&MBB, dl, get(X86::JP_4)).addMBB(TBB);
-    }
-
-    Count += 2;
+    BuildMI(&MBB, dl, get(X86::JNE_4)).addMBB(TBB);
+    ++Count;
+    BuildMI(&MBB, dl, get(X86::JP_4)).addMBB(TBB);
+    ++Count;
     break;
+  default: {
+    unsigned Opc = GetCondBranchFromCond(CC);
+    BuildMI(&MBB, dl, get(Opc)).addMBB(TBB);
+    ++Count;
+  }
   }
-
   if (FBB) {
     // Two-way Conditional branch. Insert the second branch.
     BuildMI(&MBB, dl, get(X86::JMP_4)).addMBB(FBB);
     ++Count;
   }
-
   return Count;
 }