Create a more targeted fix for not sinking instructions into a range where it
will conflict with another live range. The place which creates this scenerio is
the code in X86 that lowers a select instruction by splitting the MBBs. This
eliminates the need to check from the bottom up in an MBB for live pregs.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@106066 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index 8e336f9..9907066 100644
--- a/lib/Target/X86/X86ISelLowering.cpp
+++ b/lib/Target/X86/X86ISelLowering.cpp
@@ -8465,22 +8465,42 @@
MachineBasicBlock *sinkMBB = F->CreateMachineBasicBlock(LLVM_BB);
unsigned Opc =
X86::GetCondBranchFromCond((X86::CondCode)MI->getOperand(3).getImm());
+
BuildMI(BB, DL, TII->get(Opc)).addMBB(sinkMBB);
F->insert(It, copy0MBB);
F->insert(It, sinkMBB);
+
// Update machine-CFG edges by first adding all successors of the current
// block to the new block which will contain the Phi node for the select.
for (MachineBasicBlock::succ_iterator I = BB->succ_begin(),
E = BB->succ_end(); I != E; ++I)
sinkMBB->addSuccessor(*I);
+
// Next, remove all successors of the current block, and add the true
// and fallthrough blocks as its successors.
while (!BB->succ_empty())
BB->removeSuccessor(BB->succ_begin());
+
// Add the true and fallthrough blocks as its successors.
BB->addSuccessor(copy0MBB);
BB->addSuccessor(sinkMBB);
+ // If the EFLAGS register isn't dead in the terminator, then claim that it's
+ // live into the sink and copy blocks.
+ const MachineFunction *MF = BB->getParent();
+ const TargetRegisterInfo *TRI = MF->getTarget().getRegisterInfo();
+ BitVector ReservedRegs = TRI->getReservedRegs(*MF);
+ const MachineInstr *Term = BB->getFirstTerminator();
+
+ for (unsigned I = 0, E = Term->getNumOperands(); I != E; ++I) {
+ const MachineOperand &MO = Term->getOperand(I);
+ if (!MO.isReg() || MO.isKill() || MO.isDead()) continue;
+ unsigned Reg = MO.getReg();
+ if (Reg != X86::EFLAGS) continue;
+ copy0MBB->addLiveIn(Reg);
+ sinkMBB->addLiveIn(Reg);
+ }
+
// copy0MBB:
// %FalseValue = ...
// # fallthrough to sinkMBB