[X86] Rewrite hasReassociableOperands and setSpecialOperandAttr to not hardcode number of operands or position of the EFLAGS operand.

This makes the code immune to the MXCSR addition in D68121.

1 files changed, 19 insertions, 28 deletions

diff --git a/llvm/lib/Target/X86/X86InstrInfo.cpp b/llvm/lib/Target/X86/X86InstrInfo.cpp
index 889ba288cc2..8e491c539c3 100644
--- a/llvm/lib/Target/X86/X86InstrInfo.cpp
+++ b/llvm/lib/Target/X86/X86InstrInfo.cpp
@@ -7233,8 +7233,8 @@ bool X86InstrInfo::hasHighOperandLatency(const TargetSchedModel &SchedModel,
 
 bool X86InstrInfo::hasReassociableOperands(const MachineInstr &Inst,
                                            const MachineBasicBlock *MBB) const {
-  assert((Inst.getNumOperands() == 3 || Inst.getNumOperands() == 4) &&
-         "Reassociation needs binary operators");
+  assert(Inst.getNumExplicitOperands() == 3 && Inst.getNumExplicitDefs() == 1 &&
+         Inst.getNumDefs() <= 2 && "Reassociation needs binary operators");
 
   // Integer binary math/logic instructions have a third source operand:
   // the EFLAGS register. That operand must be both defined here and never
@@ -7242,13 +7242,11 @@ bool X86InstrInfo::hasReassociableOperands(const MachineInstr &Inst,
   // not change anything because rearranging the operands could affect other
   // instructions that depend on the exact status flags (zero, sign, etc.)
   // that are set by using these particular operands with this operation.
-  if (Inst.getNumOperands() == 4) {
-    assert(Inst.getOperand(3).isReg() &&
-           Inst.getOperand(3).getReg() == X86::EFLAGS &&
-           "Unexpected operand in reassociable instruction");
-    if (!Inst.getOperand(3).isDead())
-      return false;
-  }
+  const MachineOperand *FlagDef = Inst.findRegisterDefOperand(X86::EFLAGS);
+  assert((Inst.getNumDefs() == 1 || FlagDef) &&
+         "Implicit def isn't flags?");
+  if (FlagDef && !FlagDef->isDead())
+    return false;
 
   return TargetInstrInfo::hasReassociableOperands(Inst, MBB);
 }
@@ -7659,38 +7657,31 @@ void X86InstrInfo::setSpecialOperandAttr(MachineInstr &OldMI1,
                                          MachineInstr &OldMI2,
                                          MachineInstr &NewMI1,
                                          MachineInstr &NewMI2) const {
-  // Integer instructions define an implicit EFLAGS source register operand as
-  // the third source (fourth total) operand.
-  if (OldMI1.getNumOperands() != 4 || OldMI2.getNumOperands() != 4)
-    return;
+  // Integer instructions may define an implicit EFLAGS dest register operand.
+  MachineOperand *OldFlagDef1 = OldMI1.findRegisterDefOperand(X86::EFLAGS);
+  MachineOperand *OldFlagDef2 = OldMI2.findRegisterDefOperand(X86::EFLAGS);
 
-  assert(NewMI1.getNumOperands() == 4 && NewMI2.getNumOperands() == 4 &&
+  assert(!OldFlagDef1 == !OldFlagDef2 &&
          "Unexpected instruction type for reassociation");
 
-  MachineOperand &OldOp1 = OldMI1.getOperand(3);
-  MachineOperand &OldOp2 = OldMI2.getOperand(3);
-  MachineOperand &NewOp1 = NewMI1.getOperand(3);
-  MachineOperand &NewOp2 = NewMI2.getOperand(3);
+  if (!OldFlagDef1 || !OldFlagDef2)
+    return;
 
-  assert(OldOp1.isReg() && OldOp1.getReg() == X86::EFLAGS && OldOp1.isDead() &&
-         "Must have dead EFLAGS operand in reassociable instruction");
-  assert(OldOp2.isReg() && OldOp2.getReg() == X86::EFLAGS && OldOp2.isDead() &&
+  assert(OldFlagDef1->isDead() && OldFlagDef2->isDead() &&
          "Must have dead EFLAGS operand in reassociable instruction");
 
-  (void)OldOp1;
-  (void)OldOp2;
+  MachineOperand *NewFlagDef1 = NewMI1.findRegisterDefOperand(X86::EFLAGS);
+  MachineOperand *NewFlagDef2 = NewMI2.findRegisterDefOperand(X86::EFLAGS);
 
-  assert(NewOp1.isReg() && NewOp1.getReg() == X86::EFLAGS &&
-         "Unexpected operand in reassociable instruction");
-  assert(NewOp2.isReg() && NewOp2.getReg() == X86::EFLAGS &&
+  assert(NewFlagDef1 && NewFlagDef2 &&
          "Unexpected operand in reassociable instruction");
 
   // Mark the new EFLAGS operands as dead to be helpful to subsequent iterations
   // of this pass or other passes. The EFLAGS operands must be dead in these new
   // instructions because the EFLAGS operands in the original instructions must
   // be dead in order for reassociation to occur.
-  NewOp1.setIsDead();
-  NewOp2.setIsDead();
+  NewFlagDef1->setIsDead();
+  NewFlagDef2->setIsDead();
 }
 
 std::pair<unsigned, unsigned>