///
//===----------------------------------------------------------------------===//
-#include "PPC.h"
#include "llvm/ADT/BitVector.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/CodeGen/MachineDominators.h"
using namespace llvm;
-#define DEBUG_TYPE "ppc-branch-coalescing"
+#define DEBUG_TYPE "branch-coalescing"
+
+static cl::opt<cl::boolOrDefault>
+ EnableBranchCoalescing("enable-branch-coalesce", cl::Hidden,
+ cl::desc("enable coalescing of duplicate branches"));
STATISTIC(NumBlocksCoalesced, "Number of blocks coalesced");
STATISTIC(NumPHINotMoved, "Number of PHI Nodes that cannot be merged");
STATISTIC(NumBlocksNotCoalesced, "Number of blocks not coalesced");
-namespace llvm {
- void initializePPCBranchCoalescingPass(PassRegistry&);
-}
-
//===----------------------------------------------------------------------===//
-// PPCBranchCoalescing
+// BranchCoalescing
//===----------------------------------------------------------------------===//
///
/// Improve scheduling by coalescing branches that depend on the same condition.
/// and attempts to merge the blocks together. Such opportunities arise from
/// the expansion of select statements in the IR.
///
-/// This pass does not handle implicit operands on branch statements. In order
-/// to run on targets that use implicit operands, changes need to be made in the
-/// canCoalesceBranch and canMerge methods.
-///
-/// Example: the following LLVM IR
+/// For example, consider the following LLVM IR:
///
-/// %test = icmp eq i32 %x 0
-/// %tmp1 = select i1 %test, double %a, double 2.000000e-03
-/// %tmp2 = select i1 %test, double %b, double 5.000000e-03
+/// %test = icmp eq i32 %x 0
+/// %tmp1 = select i1 %test, double %a, double 2.000000e-03
+/// %tmp2 = select i1 %test, double %b, double 5.000000e-03
///
-/// expands to the following machine code:
+/// This IR expands to the following machine code on PowerPC:
///
/// BB#0: derived from LLVM BB %entry
/// Live Ins: %F1 %F3 %X6
namespace {
-class PPCBranchCoalescing : public MachineFunctionPass {
+class BranchCoalescing : public MachineFunctionPass {
struct CoalescingCandidateInfo {
MachineBasicBlock *BranchBlock; // Block containing the branch
MachineBasicBlock *BranchTargetBlock; // Block branched to
bool validateCandidates(CoalescingCandidateInfo &SourceRegion,
CoalescingCandidateInfo &TargetRegion) const;
+ static bool isBranchCoalescingEnabled() {
+ return EnableBranchCoalescing == cl::BOU_TRUE;
+ }
+
public:
static char ID;
- PPCBranchCoalescing() : MachineFunctionPass(ID) {
- initializePPCBranchCoalescingPass(*PassRegistry::getPassRegistry());
+ BranchCoalescing() : MachineFunctionPass(ID) {
+ initializeBranchCoalescingPass(*PassRegistry::getPassRegistry());
}
void getAnalysisUsage(AnalysisUsage &AU) const override {
};
} // End anonymous namespace.
-char PPCBranchCoalescing::ID = 0;
-/// createPPCBranchCoalescingPass - returns an instance of the Branch Coalescing
-/// Pass
-FunctionPass *llvm::createPPCBranchCoalescingPass() {
- return new PPCBranchCoalescing();
-}
+char BranchCoalescing::ID = 0;
+char &llvm::BranchCoalescingID = BranchCoalescing::ID;
-INITIALIZE_PASS_BEGIN(PPCBranchCoalescing, DEBUG_TYPE,
+INITIALIZE_PASS_BEGIN(BranchCoalescing, DEBUG_TYPE,
"Branch Coalescing", false, false)
INITIALIZE_PASS_DEPENDENCY(MachineDominatorTree)
INITIALIZE_PASS_DEPENDENCY(MachinePostDominatorTree)
-INITIALIZE_PASS_END(PPCBranchCoalescing, DEBUG_TYPE, "Branch Coalescing",
+INITIALIZE_PASS_END(BranchCoalescing, DEBUG_TYPE, "Branch Coalescing",
false, false)
-PPCBranchCoalescing::CoalescingCandidateInfo::CoalescingCandidateInfo()
+BranchCoalescing::CoalescingCandidateInfo::CoalescingCandidateInfo()
: BranchBlock(nullptr), BranchTargetBlock(nullptr),
FallThroughBlock(nullptr), MustMoveDown(false), MustMoveUp(false) {}
-void PPCBranchCoalescing::CoalescingCandidateInfo::clear() {
+void BranchCoalescing::CoalescingCandidateInfo::clear() {
BranchBlock = nullptr;
BranchTargetBlock = nullptr;
FallThroughBlock = nullptr;
MustMoveUp = false;
}
-void PPCBranchCoalescing::initialize(MachineFunction &MF) {
+void BranchCoalescing::initialize(MachineFunction &MF) {
MDT = &getAnalysis<MachineDominatorTree>();
MPDT = &getAnalysis<MachinePostDominatorTree>();
TII = MF.getSubtarget().getInstrInfo();
///\param[in,out] Cand The coalescing candidate to analyze
///\return true if and only if the branch can be coalesced, false otherwise
///
-bool PPCBranchCoalescing::canCoalesceBranch(CoalescingCandidateInfo &Cand) {
+bool BranchCoalescing::canCoalesceBranch(CoalescingCandidateInfo &Cand) {
DEBUG(dbgs() << "Determine if branch block " << Cand.BranchBlock->getNumber()
<< " can be coalesced:");
MachineBasicBlock *FalseMBB = nullptr;
if (!I.isBranch())
continue;
- // The analyzeBranch method does not include any implicit operands.
- // This is not an issue on PPC but must be handled on other targets.
- // For this pass to be made target-independent, the analyzeBranch API
- // need to be updated to support implicit operands and there would
- // need to be a way to verify that any implicit operands would not be
- // clobbered by merging blocks. This would include identifying the
- // implicit operands as well as the basic block they are defined in.
- // This could be done by changing the analyzeBranch API to have it also
- // record and return the implicit operands and the blocks where they are
- // defined. Alternatively, the BranchCoalescing code would need to be
- // extended to identify the implicit operands. The analysis in canMerge
- // must then be extended to prove that none of the implicit operands are
- // changed in the blocks that are combined during coalescing.
if (I.getNumOperands() != I.getNumExplicitOperands()) {
DEBUG(dbgs() << "Terminator contains implicit operands - skip : " << I
<< "\n");
/// \param[in] OpList2 operand list
/// \return true if and only if the operands lists are identical
///
-bool PPCBranchCoalescing::identicalOperands(
+bool BranchCoalescing::identicalOperands(
ArrayRef<MachineOperand> OpList1, ArrayRef<MachineOperand> OpList2) const {
if (OpList1.size() != OpList2.size()) {
/// \param[in] SourceMBB block to move PHI instructions from
/// \param[in] TargetMBB block to move PHI instructions to
///
-void PPCBranchCoalescing::moveAndUpdatePHIs(MachineBasicBlock *SourceMBB,
+void BranchCoalescing::moveAndUpdatePHIs(MachineBasicBlock *SourceMBB,
MachineBasicBlock *TargetMBB) {
MachineBasicBlock::iterator MI = SourceMBB->begin();
/// \return true if it is safe to move MI to beginning of TargetMBB,
/// false otherwise.
///
-bool PPCBranchCoalescing::canMoveToBeginning(const MachineInstr &MI,
+bool BranchCoalescing::canMoveToBeginning(const MachineInstr &MI,
const MachineBasicBlock &TargetMBB
) const {
/// \return true if it is safe to move MI to end of TargetMBB,
/// false otherwise.
///
-bool PPCBranchCoalescing::canMoveToEnd(const MachineInstr &MI,
+bool BranchCoalescing::canMoveToEnd(const MachineInstr &MI,
const MachineBasicBlock &TargetMBB
) const {
/// \return true if all instructions in SourceRegion.BranchBlock can be merged
/// into a block in TargetRegion; false otherwise.
///
-bool PPCBranchCoalescing::validateCandidates(
+bool BranchCoalescing::validateCandidates(
CoalescingCandidateInfo &SourceRegion,
CoalescingCandidateInfo &TargetRegion) const {
/// \return true if all instructions in SourceRegion.BranchBlock can be merged
/// into a block in TargetRegion, false otherwise.
///
-bool PPCBranchCoalescing::canMerge(CoalescingCandidateInfo &SourceRegion,
+bool BranchCoalescing::canMerge(CoalescingCandidateInfo &SourceRegion,
CoalescingCandidateInfo &TargetRegion) const {
if (!validateCandidates(SourceRegion, TargetRegion))
return false;
/// \param[in] SourceRegion The candidate to move blocks from
/// \param[in] TargetRegion The candidate to move blocks to
///
-bool PPCBranchCoalescing::mergeCandidates(CoalescingCandidateInfo &SourceRegion,
+bool BranchCoalescing::mergeCandidates(CoalescingCandidateInfo &SourceRegion,
CoalescingCandidateInfo &TargetRegion) {
if (SourceRegion.MustMoveUp && SourceRegion.MustMoveDown) {
return true;
}
-bool PPCBranchCoalescing::runOnMachineFunction(MachineFunction &MF) {
+bool BranchCoalescing::runOnMachineFunction(MachineFunction &MF) {
- if (skipFunction(*MF.getFunction()) || MF.empty())
+ if (skipFunction(*MF.getFunction()) || MF.empty() ||
+ !isBranchCoalescingEnabled())
return false;
bool didSomething = false;
-; RUN: llc -mtriple=powerpc64le-unknown-linux-gnu -verify-machineinstrs < %s | FileCheck %s
-; RUN: llc -mcpu=pwr8 -mtriple=powerpc64-unknown-linux-gnu -verify-machineinstrs < %s | FileCheck %s
-; RUN: llc -mtriple=powerpc64le-unknown-linux-gnu -verify-machineinstrs -disable-ppc-branch-coalesce < %s | FileCheck --check-prefix=CHECK-NOCOALESCE %s
-; RUN: llc -mcpu=pwr8 -mtriple=powerpc64-unknown-linux-gnu -verify-machineinstrs -disable-ppc-branch-coalesce < %s | FileCheck --check-prefix=CHECK-NOCOALESCE %s
+; RUN: llc -mcpu=pwr8 -mtriple=powerpc64le-unknown-linux-gnu -verify-machineinstrs -enable-branch-coalesce=true < %s | FileCheck %s
+; RUN: llc -mcpu=pwr8 -mtriple=powerpc64-unknown-linux-gnu -verify-machineinstrs -enable-branch-coalesce=true < %s | FileCheck %s
; Function Attrs: nounwind
define double @testBranchCoal(double %a, double %b, double %c, i32 %x) {
+entry:
+ %test = icmp eq i32 %x, 0
+ %tmp1 = select i1 %test, double %a, double 2.000000e-03
+ %tmp2 = select i1 %test, double %b, double 0.000000e+00
+ %tmp3 = select i1 %test, double %c, double 5.000000e-03
-; CHECK-LABEL: @testBranchCoal
+ %res1 = fadd double %tmp1, %tmp2
+ %result = fadd double %res1, %tmp3
+ ret double %result
+
+; CHECK-LABEL: @testBranchCoal
; CHECK: cmplwi [[CMPR:[0-7]+]], 6, 0
; CHECK: beq [[CMPR]], .LBB[[LAB1:[0-9_]+]]
; CHECK-DAG: addis [[LD1REG:[0-9]+]], 2, .LCPI0_0@toc@ha
; CHECK-DAG: addis [[LD2REG:[0-9]+]], 2, .LCPI0_1@toc@ha
; CHECK-DAG: xxlxor 2, 2, 2
-; CHECK-NOT: beq
-; CHECK-DAG: addi [[LD1BASE:[0-9]+]], [[LD1REG]]
+; CHECK-NOT: beq
+; CHECK-DAG: addi [[LD1BASE:[0-9]+]], [[LD1REG]]
; CHECK-DAG: addi [[LD2BASE:[0-9]+]], [[LD2REG]]
; CHECK-DAG: lxsdx 1, 0, [[LD1BASE]]
; CHECK-DAG: lxsdx 3, 0, [[LD2BASE]]
; CHECK: xsadddp 0, 1, 2
; CHECK: xsadddp 1, 0, 3
; CHECK: blr
-
-; CHECK-NOCOALESCE-LABEL: testBranchCoal:
-; CHECK-NOCOALESCE: # BB#0: # %entry
-; CHECK-NOCOALESCE-NEXT: cmplwi 0, 6, 0
-; CHECK-NOCOALESCE-NEXT: bne 0, .LBB0_5
-; CHECK-NOCOALESCE-NEXT: # BB#1: # %entry
-; CHECK-NOCOALESCE-NEXT: bne 0, .LBB0_6
-; CHECK-NOCOALESCE-NEXT: .LBB0_2: # %entry
-; CHECK-NOCOALESCE-NEXT: beq 0, .LBB0_4
-; CHECK-NOCOALESCE-NEXT: .LBB0_3: # %entry
-; CHECK-NOCOALESCE-NEXT: addis 3, 2, .LCPI0_1@toc@ha
-; CHECK-NOCOALESCE-NEXT: addi 3, 3, .LCPI0_1@toc@l
-; CHECK-NOCOALESCE-NEXT: lxsdx 3, 0, 3
-; CHECK-NOCOALESCE-NEXT: .LBB0_4: # %entry
-; CHECK-NOCOALESCE-NEXT: xsadddp 0, 1, 2
-; CHECK-NOCOALESCE-NEXT: xsadddp 1, 0, 3
-; CHECK-NOCOALESCE-NEXT: blr
-; CHECK-NOCOALESCE-NEXT: .LBB0_5: # %entry
-; CHECK-NOCOALESCE-NEXT: addis 3, 2, .LCPI0_0@toc@ha
-; CHECK-NOCOALESCE-NEXT: addi 3, 3, .LCPI0_0@toc@l
-; CHECK-NOCOALESCE-NEXT: lxsdx 1, 0, 3
-; CHECK-NOCOALESCE-NEXT: beq 0, .LBB0_2
-; CHECK-NOCOALESCE-NEXT: .LBB0_6: # %entry
-; CHECK-NOCOALESCE-NEXT: xxlxor 2, 2, 2
-; CHECK-NOCOALESCE-NEXT: bne 0, .LBB0_3
-; CHECK-NOCOALESCE-NEXT: b .LBB0_4
- entry:
-
- %test = icmp eq i32 %x, 0
- %tmp1 = select i1 %test, double %a, double 2.000000e-03
- %tmp2 = select i1 %test, double %b, double 0.000000e+00
- %tmp3 = select i1 %test, double %c, double 5.000000e-03
-
- %res1 = fadd double %tmp1, %tmp2
- %result = fadd double %res1, %tmp3
- ret double %result
}