return (CC <= SPCC::ICC_VC);
}
-
static SPCC::CondCodes GetOppositeBranchCondition(SPCC::CondCodes CC)
{
switch(CC) {
llvm_unreachable("Invalid cond code");
}
-bool SparcInstrInfo::AnalyzeBranch(MachineBasicBlock &MBB,
- MachineBasicBlock *&TBB,
- MachineBasicBlock *&FBB,
- SmallVectorImpl<MachineOperand> &Cond,
- bool AllowModify) const
-{
-
- MachineBasicBlock::iterator I = MBB.end();
- MachineBasicBlock::iterator UnCondBrIter = MBB.end();
- while (I != MBB.begin()) {
- --I;
+static bool isUncondBranchOpcode(int Opc) { return Opc == SP::BA; }
- if (I->isDebugValue())
- continue;
+static bool isCondBranchOpcode(int Opc) {
+ return Opc == SP::FBCOND || Opc == SP::BCOND;
+}
- // When we see a non-terminator, we are done.
- if (!isUnpredicatedTerminator(I))
- break;
+static bool isIndirectBranchOpcode(int Opc) {
+ return Opc == SP::BINDrr || Opc == SP::BINDri;
+}
- // Terminator is not a branch.
- if (!I->isBranch())
- return true;
+static void parseCondBranch(MachineInstr *LastInst, MachineBasicBlock *&Target,
+ SmallVectorImpl<MachineOperand> &Cond) {
+ Cond.push_back(MachineOperand::CreateImm(LastInst->getOperand(1).getImm()));
+ Target = LastInst->getOperand(0).getMBB();
+}
- // Handle Unconditional branches.
- if (I->getOpcode() == SP::BA) {
- UnCondBrIter = I;
+bool SparcInstrInfo::AnalyzeBranch(MachineBasicBlock &MBB,
+ MachineBasicBlock *&TBB,
+ MachineBasicBlock *&FBB,
+ SmallVectorImpl<MachineOperand> &Cond,
+ bool AllowModify) const {
+ MachineBasicBlock::iterator I = MBB.getLastNonDebugInstr();
+ if (I == MBB.end())
+ return false;
+
+ if (!isUnpredicatedTerminator(I))
+ return false;
+
+ // Get the last instruction in the block.
+ MachineInstr *LastInst = I;
+ unsigned LastOpc = LastInst->getOpcode();
+
+ // If there is only one terminator instruction, process it.
+ if (I == MBB.begin() || !isUnpredicatedTerminator(--I)) {
+ if (isUncondBranchOpcode(LastOpc)) {
+ TBB = LastInst->getOperand(0).getMBB();
+ return false;
+ }
+ if (isCondBranchOpcode(LastOpc)) {
+ // Block ends with fall-through condbranch.
+ parseCondBranch(LastInst, TBB, Cond);
+ return false;
+ }
+ return true; // Can't handle indirect branch.
+ }
- if (!AllowModify) {
- TBB = I->getOperand(0).getMBB();
- continue;
+ // Get the instruction before it if it is a terminator.
+ MachineInstr *SecondLastInst = I;
+ unsigned SecondLastOpc = SecondLastInst->getOpcode();
+
+ // If AllowModify is true and the block ends with two or more unconditional
+ // branches, delete all but the first unconditional branch.
+ if (AllowModify && isUncondBranchOpcode(LastOpc)) {
+ while (isUncondBranchOpcode(SecondLastOpc)) {
+ LastInst->eraseFromParent();
+ LastInst = SecondLastInst;
+ LastOpc = LastInst->getOpcode();
+ if (I == MBB.begin() || !isUnpredicatedTerminator(--I)) {
+ // Return now the only terminator is an unconditional branch.
+ TBB = LastInst->getOperand(0).getMBB();
+ return false;
+ } else {
+ SecondLastInst = I;
+ SecondLastOpc = SecondLastInst->getOpcode();
}
+ }
+ }
- while (std::next(I) != MBB.end())
- std::next(I)->eraseFromParent();
-
- Cond.clear();
- FBB = nullptr;
+ // If there are three terminators, we don't know what sort of block this is.
+ if (SecondLastInst && I != MBB.begin() && isUnpredicatedTerminator(--I))
+ return true;
- if (MBB.isLayoutSuccessor(I->getOperand(0).getMBB())) {
- TBB = nullptr;
- I->eraseFromParent();
- I = MBB.end();
- UnCondBrIter = MBB.end();
- continue;
- }
+ // If the block ends with a B and a Bcc, handle it.
+ if (isCondBranchOpcode(SecondLastOpc) && isUncondBranchOpcode(LastOpc)) {
+ parseCondBranch(SecondLastInst, TBB, Cond);
+ FBB = LastInst->getOperand(0).getMBB();
+ return false;
+ }
- TBB = I->getOperand(0).getMBB();
- continue;
- }
+ // If the block ends with two unconditional branches, handle it. The second
+ // one is not executed.
+ if (isUncondBranchOpcode(SecondLastOpc) && isUncondBranchOpcode(LastOpc)) {
+ TBB = SecondLastInst->getOperand(0).getMBB();
+ return false;
+ }
- unsigned Opcode = I->getOpcode();
- if (Opcode != SP::BCOND && Opcode != SP::FBCOND)
- return true; // Unknown Opcode.
-
- SPCC::CondCodes BranchCode = (SPCC::CondCodes)I->getOperand(1).getImm();
-
- if (Cond.empty()) {
- MachineBasicBlock *TargetBB = I->getOperand(0).getMBB();
- if (AllowModify && UnCondBrIter != MBB.end() &&
- MBB.isLayoutSuccessor(TargetBB)) {
-
- // Transform the code
- //
- // brCC L1
- // ba L2
- // L1:
- // ..
- // L2:
- //
- // into
- //
- // brnCC L2
- // L1:
- // ...
- // L2:
- //
- BranchCode = GetOppositeBranchCondition(BranchCode);
- MachineBasicBlock::iterator OldInst = I;
- BuildMI(MBB, UnCondBrIter, MBB.findDebugLoc(I), get(Opcode))
- .addMBB(UnCondBrIter->getOperand(0).getMBB()).addImm(BranchCode);
- BuildMI(MBB, UnCondBrIter, MBB.findDebugLoc(I), get(SP::BA))
- .addMBB(TargetBB);
-
- OldInst->eraseFromParent();
- UnCondBrIter->eraseFromParent();
-
- UnCondBrIter = MBB.end();
- I = MBB.end();
- continue;
- }
- FBB = TBB;
- TBB = I->getOperand(0).getMBB();
- Cond.push_back(MachineOperand::CreateImm(BranchCode));
- continue;
- }
- // FIXME: Handle subsequent conditional branches.
- // For now, we can't handle multiple conditional branches.
+ // ...likewise if it ends with an indirect branch followed by an unconditional
+ // branch.
+ if (isIndirectBranchOpcode(SecondLastOpc) && isUncondBranchOpcode(LastOpc)) {
+ I = LastInst;
+ if (AllowModify)
+ I->eraseFromParent();
return true;
}
- return false;
+
+ // Otherwise, can't handle this.
+ return true;
}
unsigned
return Count;
}
+bool SparcInstrInfo::ReverseBranchCondition(
+ SmallVectorImpl<MachineOperand> &Cond) const {
+ assert(Cond.size() == 1);
+ SPCC::CondCodes CC = static_cast<SPCC::CondCodes>(Cond[0].getImm());
+ Cond[0].setImm(GetOppositeBranchCondition(CC));
+ return false;
+}
+
void SparcInstrInfo::copyPhysReg(MachineBasicBlock &MBB,
MachineBasicBlock::iterator I, DebugLoc DL,
unsigned DestReg, unsigned SrcReg,
--- /dev/null
+; RUN: llc -mtriple=sparc-none-linux-gnu < %s | FileCheck %s
+
+; This test checks that LLVM can do basic stripping and reapplying of branches
+; to basic blocks.
+
+declare void @test_true()
+declare void @test_false()
+
+; !0 corresponds to a branch being taken, !1 to not being takne.
+!0 = !{!"branch_weights", i32 64, i32 4}
+!1 = !{!"branch_weights", i32 4, i32 64}
+
+define void @test_Bcc_fallthrough_taken(i32 %in) nounwind {
+; CHECK-LABEL: test_Bcc_fallthrough_taken:
+ %tst = icmp eq i32 %in, 42
+ br i1 %tst, label %true, label %false, !prof !0
+
+; CHECK: cmp {{%[goli][0-9]+}}, 42
+; CHECK: bne [[FALSE:.LBB[0-9]+_[0-9]+]]
+; CHECK-NEXT: nop
+; CHECK-NEXT: ! BB#
+; CHECK-NEXT: call test_true
+
+; CHECK: [[FALSE]]:
+; CHECK: call test_false
+
+true:
+ call void @test_true()
+ ret void
+
+false:
+ call void @test_false()
+ ret void
+}
+
+define void @test_Bcc_fallthrough_nottaken(i32 %in) nounwind {
+; CHECK-LABEL: test_Bcc_fallthrough_nottaken:
+ %tst = icmp eq i32 %in, 42
+ br i1 %tst, label %true, label %false, !prof !1
+
+; CHECK: cmp {{%[goli][0-9]+}}, 42
+
+; CHECK: be [[TRUE:.LBB[0-9]+_[0-9]+]]
+; CHECK-NEXT: nop
+; CHECK-NEXT: ! BB#
+; CHECK-NEXT: call test_false
+
+; CHECK: [[TRUE]]:
+; CHECK: call test_true
+
+true:
+ call void @test_true()
+ ret void
+
+false:
+ call void @test_false()
+ ret void
+}
projects / oota-llvm.git / commitdiff