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-rw-r--r--lib/CodeGen/BranchFolding.cpp37
-rw-r--r--lib/CodeGen/MachineCopyPropagation.cpp48
-rw-r--r--lib/CodeGen/RegisterCoalescer.cpp38
3 files changed, 60 insertions, 63 deletions
diff --git a/lib/CodeGen/BranchFolding.cpp b/lib/CodeGen/BranchFolding.cpp
index a898e327ccc2b..6fba161033b02 100644
--- a/lib/CodeGen/BranchFolding.cpp
+++ b/lib/CodeGen/BranchFolding.cpp
@@ -49,7 +49,6 @@ STATISTIC(NumDeadBlocks, "Number of dead blocks removed");
STATISTIC(NumBranchOpts, "Number of branches optimized");
STATISTIC(NumTailMerge , "Number of block tails merged");
STATISTIC(NumHoist , "Number of times common instructions are hoisted");
-STATISTIC(NumTailCalls, "Number of tail calls optimized");
static cl::opt<cl::boolOrDefault> FlagEnableTailMerge("enable-tail-merge",
cl::init(cl::BOU_UNSET), cl::Hidden);
@@ -1387,42 +1386,6 @@ ReoptimizeBlock:
}
}
- if (!IsEmptyBlock(MBB) && MBB->pred_size() == 1 &&
- MF.getFunction()->optForSize()) {
- // Changing "Jcc foo; foo: jmp bar;" into "Jcc bar;" might change the branch
- // direction, thereby defeating careful block placement and regressing
- // performance. Therefore, only consider this for optsize functions.
- MachineInstr &TailCall = *MBB->getFirstNonDebugInstr();
- if (TII->isUnconditionalTailCall(TailCall)) {
- MachineBasicBlock *Pred = *MBB->pred_begin();
- MachineBasicBlock *PredTBB = nullptr, *PredFBB = nullptr;
- SmallVector<MachineOperand, 4> PredCond;
- bool PredAnalyzable =
- !TII->analyzeBranch(*Pred, PredTBB, PredFBB, PredCond, true);
-
- if (PredAnalyzable && !PredCond.empty() && PredTBB == MBB) {
- // The predecessor has a conditional branch to this block which consists
- // of only a tail call. Try to fold the tail call into the conditional
- // branch.
- if (TII->canMakeTailCallConditional(PredCond, TailCall)) {
- // TODO: It would be nice if analyzeBranch() could provide a pointer
- // to the branch insturction so replaceBranchWithTailCall() doesn't
- // have to search for it.
- TII->replaceBranchWithTailCall(*Pred, PredCond, TailCall);
- ++NumTailCalls;
- Pred->removeSuccessor(MBB);
- MadeChange = true;
- return MadeChange;
- }
- }
- // If the predecessor is falling through to this block, we could reverse
- // the branch condition and fold the tail call into that. However, after
- // that we might have to re-arrange the CFG to fall through to the other
- // block and there is a high risk of regressing code size rather than
- // improving it.
- }
- }
-
// Analyze the branch in the current block.
MachineBasicBlock *CurTBB = nullptr, *CurFBB = nullptr;
SmallVector<MachineOperand, 4> CurCond;
diff --git a/lib/CodeGen/MachineCopyPropagation.cpp b/lib/CodeGen/MachineCopyPropagation.cpp
index 92d043df26b85..5de6dec29fb9d 100644
--- a/lib/CodeGen/MachineCopyPropagation.cpp
+++ b/lib/CodeGen/MachineCopyPropagation.cpp
@@ -61,6 +61,7 @@ namespace {
private:
void ClobberRegister(unsigned Reg);
+ void ReadRegister(unsigned Reg);
void CopyPropagateBlock(MachineBasicBlock &MBB);
bool eraseIfRedundant(MachineInstr &Copy, unsigned Src, unsigned Def);
@@ -120,6 +121,18 @@ void MachineCopyPropagation::ClobberRegister(unsigned Reg) {
}
}
+void MachineCopyPropagation::ReadRegister(unsigned Reg) {
+ // If 'Reg' is defined by a copy, the copy is no longer a candidate
+ // for elimination.
+ for (MCRegAliasIterator AI(Reg, TRI, true); AI.isValid(); ++AI) {
+ Reg2MIMap::iterator CI = CopyMap.find(*AI);
+ if (CI != CopyMap.end()) {
+ DEBUG(dbgs() << "MCP: Copy is used - not dead: "; CI->second->dump());
+ MaybeDeadCopies.remove(CI->second);
+ }
+ }
+}
+
/// Return true if \p PreviousCopy did copy register \p Src to register \p Def.
/// This fact may have been obscured by sub register usage or may not be true at
/// all even though Src and Def are subregisters of the registers used in
@@ -212,12 +225,14 @@ void MachineCopyPropagation::CopyPropagateBlock(MachineBasicBlock &MBB) {
// If Src is defined by a previous copy, the previous copy cannot be
// eliminated.
- for (MCRegAliasIterator AI(Src, TRI, true); AI.isValid(); ++AI) {
- Reg2MIMap::iterator CI = CopyMap.find(*AI);
- if (CI != CopyMap.end()) {
- DEBUG(dbgs() << "MCP: Copy is no longer dead: "; CI->second->dump());
- MaybeDeadCopies.remove(CI->second);
- }
+ ReadRegister(Src);
+ for (const MachineOperand &MO : MI->implicit_operands()) {
+ if (!MO.isReg() || !MO.readsReg())
+ continue;
+ unsigned Reg = MO.getReg();
+ if (!Reg)
+ continue;
+ ReadRegister(Reg);
}
DEBUG(dbgs() << "MCP: Copy is a deletion candidate: "; MI->dump());
@@ -234,6 +249,14 @@ void MachineCopyPropagation::CopyPropagateBlock(MachineBasicBlock &MBB) {
// ...
// %xmm2<def> = copy %xmm9
ClobberRegister(Def);
+ for (const MachineOperand &MO : MI->implicit_operands()) {
+ if (!MO.isReg() || !MO.isDef())
+ continue;
+ unsigned Reg = MO.getReg();
+ if (!Reg)
+ continue;
+ ClobberRegister(Reg);
+ }
// Remember Def is defined by the copy.
for (MCSubRegIterator SR(Def, TRI, /*IncludeSelf=*/true); SR.isValid();
@@ -268,17 +291,8 @@ void MachineCopyPropagation::CopyPropagateBlock(MachineBasicBlock &MBB) {
if (MO.isDef()) {
Defs.push_back(Reg);
- continue;
- }
-
- // If 'Reg' is defined by a copy, the copy is no longer a candidate
- // for elimination.
- for (MCRegAliasIterator AI(Reg, TRI, true); AI.isValid(); ++AI) {
- Reg2MIMap::iterator CI = CopyMap.find(*AI);
- if (CI != CopyMap.end()) {
- DEBUG(dbgs() << "MCP: Copy is used - not dead: "; CI->second->dump());
- MaybeDeadCopies.remove(CI->second);
- }
+ } else {
+ ReadRegister(Reg);
}
// Treat undef use like defs for copy propagation but not for
// dead copy. We would need to do a liveness check to be sure the copy
diff --git a/lib/CodeGen/RegisterCoalescer.cpp b/lib/CodeGen/RegisterCoalescer.cpp
index 0f4bb59c49a5b..4bb3c229afc58 100644
--- a/lib/CodeGen/RegisterCoalescer.cpp
+++ b/lib/CodeGen/RegisterCoalescer.cpp
@@ -1556,9 +1556,10 @@ bool RegisterCoalescer::joinCopy(MachineInstr *CopyMI, bool &Again) {
bool RegisterCoalescer::joinReservedPhysReg(CoalescerPair &CP) {
unsigned DstReg = CP.getDstReg();
+ unsigned SrcReg = CP.getSrcReg();
assert(CP.isPhys() && "Must be a physreg copy");
assert(MRI->isReserved(DstReg) && "Not a reserved register");
- LiveInterval &RHS = LIS->getInterval(CP.getSrcReg());
+ LiveInterval &RHS = LIS->getInterval(SrcReg);
DEBUG(dbgs() << "\t\tRHS = " << RHS << '\n');
assert(RHS.containsOneValue() && "Invalid join with reserved register");
@@ -1592,17 +1593,36 @@ bool RegisterCoalescer::joinReservedPhysReg(CoalescerPair &CP) {
// Delete the identity copy.
MachineInstr *CopyMI;
if (CP.isFlipped()) {
- CopyMI = MRI->getVRegDef(RHS.reg);
+ // Physreg is copied into vreg
+ // %vregY = COPY %X
+ // ... //< no other def of %X here
+ // use %vregY
+ // =>
+ // ...
+ // use %X
+ CopyMI = MRI->getVRegDef(SrcReg);
} else {
- if (!MRI->hasOneNonDBGUse(RHS.reg)) {
+ // VReg is copied into physreg:
+ // %vregX = def
+ // ... //< no other def or use of %Y here
+ // %Y = COPY %vregX
+ // =>
+ // %Y = def
+ // ...
+ if (!MRI->hasOneNonDBGUse(SrcReg)) {
DEBUG(dbgs() << "\t\tMultiple vreg uses!\n");
return false;
}
- MachineInstr *DestMI = MRI->getVRegDef(RHS.reg);
- CopyMI = &*MRI->use_instr_nodbg_begin(RHS.reg);
- const SlotIndex CopyRegIdx = LIS->getInstructionIndex(*CopyMI).getRegSlot();
- const SlotIndex DestRegIdx = LIS->getInstructionIndex(*DestMI).getRegSlot();
+ if (!LIS->intervalIsInOneMBB(RHS)) {
+ DEBUG(dbgs() << "\t\tComplex control flow!\n");
+ return false;
+ }
+
+ MachineInstr &DestMI = *MRI->getVRegDef(SrcReg);
+ CopyMI = &*MRI->use_instr_nodbg_begin(SrcReg);
+ SlotIndex CopyRegIdx = LIS->getInstructionIndex(*CopyMI).getRegSlot();
+ SlotIndex DestRegIdx = LIS->getInstructionIndex(DestMI).getRegSlot();
if (!MRI->isConstantPhysReg(DstReg)) {
// We checked above that there are no interfering defs of the physical
@@ -1629,8 +1649,8 @@ bool RegisterCoalescer::joinReservedPhysReg(CoalescerPair &CP) {
// We're going to remove the copy which defines a physical reserved
// register, so remove its valno, etc.
- DEBUG(dbgs() << "\t\tRemoving phys reg def of " << DstReg << " at "
- << CopyRegIdx << "\n");
+ DEBUG(dbgs() << "\t\tRemoving phys reg def of " << PrintReg(DstReg, TRI)
+ << " at " << CopyRegIdx << "\n");
LIS->removePhysRegDefAt(DstReg, CopyRegIdx);
// Create a new dead def at the new def location.
generated by cgit v1.2.3 (git 2.25.1) at 2025-08-02 01:11:31 +0000