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-rw-r--r--lib/CodeGen/SplitKit.cpp214
-rw-r--r--lib/CodeGen/SplitKit.h66
2 files changed, 279 insertions, 1 deletions
diff --git a/lib/CodeGen/SplitKit.cpp b/lib/CodeGen/SplitKit.cpp
index a8387066a0..b081bf3733 100644
--- a/lib/CodeGen/SplitKit.cpp
+++ b/lib/CodeGen/SplitKit.cpp
@@ -17,7 +17,7 @@
#include "VirtRegMap.h"
#include "llvm/CodeGen/CalcSpillWeights.h"
#include "llvm/CodeGen/LiveIntervalAnalysis.h"
-#include "llvm/CodeGen/MachineFunctionPass.h"
+#include "llvm/CodeGen/MachineDominators.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineLoopInfo.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
@@ -337,6 +337,218 @@ bool SplitAnalysis::getMultiUseBlocks(BlockPtrSet &Blocks) {
}
//===----------------------------------------------------------------------===//
+// LiveIntervalMap
+//===----------------------------------------------------------------------===//
+
+// defValue - Introduce a li_ def for ParentVNI that could be later than
+// ParentVNI->def.
+VNInfo *LiveIntervalMap::defValue(const VNInfo *ParentVNI, SlotIndex Idx) {
+ assert(ParentVNI && "Mapping NULL value");
+ assert(Idx.isValid() && "Invalid SlotIndex");
+ assert(parentli_.getVNInfoAt(Idx) == ParentVNI && "Bad ParentVNI");
+
+ // Is this a simple 1-1 mapping? Not likely.
+ if (Idx == ParentVNI->def)
+ return mapValue(ParentVNI, Idx);
+
+ // This is a complex def. Mark with a NULL in valueMap.
+ VNInfo *OldVNI =
+ valueMap_.insert(ValueMap::value_type(ParentVNI, 0)).first->second;
+ (void)OldVNI;
+ assert(OldVNI == 0 && "Simple/Complex values mixed");
+
+ // Should we insert a minimal snippet of VNI LiveRange, or can we count on
+ // callers to do that? We need it for lookups of complex values.
+ VNInfo *VNI = li_.getNextValue(Idx, 0, true, lis_.getVNInfoAllocator());
+ return VNI;
+}
+
+// mapValue - Find the mapped value for ParentVNI at Idx.
+// Potentially create phi-def values.
+VNInfo *LiveIntervalMap::mapValue(const VNInfo *ParentVNI, SlotIndex Idx) {
+ assert(ParentVNI && "Mapping NULL value");
+ assert(Idx.isValid() && "Invalid SlotIndex");
+ assert(parentli_.getVNInfoAt(Idx) == ParentVNI && "Bad ParentVNI");
+
+ // Use insert for lookup, so we can add missing values with a second lookup.
+ std::pair<ValueMap::iterator,bool> InsP =
+ valueMap_.insert(ValueMap::value_type(ParentVNI, 0));
+
+ // This was an unknown value. Create a simple mapping.
+ if (InsP.second)
+ return InsP.first->second = li_.createValueCopy(ParentVNI,
+ lis_.getVNInfoAllocator());
+ // This was a simple mapped value.
+ if (InsP.first->second)
+ return InsP.first->second;
+
+ // This is a complex mapped value. There may be multiple defs, and we may need
+ // to create phi-defs.
+ MachineBasicBlock *IdxMBB = lis_.getMBBFromIndex(Idx);
+ assert(IdxMBB && "No MBB at Idx");
+
+ // Is there a def in the same MBB we can extend?
+ if (VNInfo *VNI = extendTo(IdxMBB, Idx))
+ return VNI;
+
+ // Now for the fun part. We know that ParentVNI potentially has multiple defs,
+ // and we may need to create even more phi-defs to preserve VNInfo SSA form.
+ // Perform a depth-first search for predecessor blocks where we know the
+ // dominating VNInfo. Insert phi-def VNInfos along the path back to IdxMBB.
+
+ // Track MBBs where we have created or learned the dominating value.
+ // This may change during the DFS as we create new phi-defs.
+ typedef DenseMap<MachineBasicBlock*, VNInfo*> MBBValueMap;
+ MBBValueMap DomValue;
+
+ for (idf_iterator<MachineBasicBlock*>
+ IDFI = idf_begin(IdxMBB),
+ IDFE = idf_end(IdxMBB); IDFI != IDFE;) {
+ MachineBasicBlock *MBB = *IDFI;
+ SlotIndex End = lis_.getMBBEndIdx(MBB);
+
+ // We are operating on the restricted CFG where ParentVNI is live.
+ if (parentli_.getVNInfoAt(End.getPrevSlot()) != ParentVNI) {
+ IDFI.skipChildren();
+ continue;
+ }
+
+ // Do we have a dominating value in this block?
+ VNInfo *VNI = extendTo(MBB, End);
+ if (!VNI) {
+ ++IDFI;
+ continue;
+ }
+
+ // Yes, VNI dominates MBB. Track the path back to IdxMBB, creating phi-defs
+ // as needed along the way.
+ for (unsigned PI = IDFI.getPathLength()-1; PI != 0; --PI) {
+ // Start from MBB's immediate successor.
+ MachineBasicBlock *Succ = IDFI.getPath(PI-1);
+ std::pair<MBBValueMap::iterator, bool> InsP =
+ DomValue.insert(MBBValueMap::value_type(Succ, VNI));
+ SlotIndex Start = lis_.getMBBStartIdx(Succ);
+ if (InsP.second) {
+ // This is the first time we backtrack to Succ. Verify dominance.
+ if (Succ->pred_size() == 1 || dt_.dominates(MBB, Succ))
+ continue;
+ } else if (InsP.first->second == VNI ||
+ InsP.first->second->def == Start) {
+ // We have previously backtracked VNI to Succ, or Succ already has a
+ // phi-def. No need to backtrack further.
+ break;
+ }
+ // VNI does not dominate Succ, we need a new phi-def.
+ VNI = li_.getNextValue(Start, 0, true, lis_.getVNInfoAllocator());
+ VNI->setIsPHIDef(true);
+ InsP.first->second = VNI;
+ MBB = Succ;
+ }
+
+ // No need to search the children, we found a dominating value.
+ // FIXME: We could prune up to the last phi-def we inserted, need df_iterator
+ // for that.
+ IDFI.skipChildren();
+ }
+
+ // The search should at least find a dominating value for IdxMBB.
+ assert(!DomValue.empty() && "Couldn't find a reaching definition");
+
+ // Since we went through the trouble of a full DFS visiting all reaching defs,
+ // the values in DomValue are now accurate. No more phi-defs are needed for
+ // these blocks, so we can color the live ranges.
+ // This makes the next mapValue call much faster.
+ VNInfo *IdxVNI = 0;
+ for (MBBValueMap::iterator I = DomValue.begin(), E = DomValue.end(); I != E;
+ ++I) {
+ MachineBasicBlock *MBB = I->first;
+ VNInfo *VNI = I->second;
+ SlotIndex Start = lis_.getMBBStartIdx(MBB);
+ if (MBB == IdxMBB) {
+ // Don't add full liveness to IdxMBB, stop at Idx.
+ if (Start != Idx)
+ li_.addRange(LiveRange(Start, Idx, VNI));
+ IdxVNI = VNI;
+ } else
+ li_.addRange(LiveRange(Start, lis_.getMBBEndIdx(MBB), VNI));
+ }
+
+ assert(IdxVNI && "Didn't find value for Idx");
+ return IdxVNI;
+}
+
+// extendTo - Find the last li_ value defined in MBB at or before Idx. The
+// parentli_ is assumed to be live at Idx. Extend the live range to Idx.
+// Return the found VNInfo, or NULL.
+VNInfo *LiveIntervalMap::extendTo(MachineBasicBlock *MBB, SlotIndex Idx) {
+ LiveInterval::iterator I = std::upper_bound(li_.begin(), li_.end(), Idx);
+ if (I == li_.begin())
+ return 0;
+ --I;
+ if (I->start < lis_.getMBBStartIdx(MBB))
+ return 0;
+ if (I->end < Idx)
+ I->end = Idx;
+ return I->valno;
+}
+
+// addSimpleRange - Add a simple range from parentli_ to li_.
+// ParentVNI must be live in the [Start;End) interval.
+void LiveIntervalMap::addSimpleRange(SlotIndex Start, SlotIndex End,
+ const VNInfo *ParentVNI) {
+ VNInfo *VNI = mapValue(ParentVNI, Start);
+ // A simple mappoing is easy.
+ if (VNI->def == ParentVNI->def) {
+ li_.addRange(LiveRange(Start, End, VNI));
+ return;
+ }
+
+ // ParentVNI is a complex value. We must map per MBB.
+ MachineFunction::iterator MBB = lis_.getMBBFromIndex(Start);
+ MachineFunction::iterator MBBE = lis_.getMBBFromIndex(End);
+
+ if (MBB == MBBE) {
+ li_.addRange(LiveRange(Start, End, VNI));
+ return;
+ }
+
+ // First block.
+ li_.addRange(LiveRange(Start, lis_.getMBBEndIdx(MBB), VNI));
+
+ // Run sequence of full blocks.
+ for (++MBB; MBB != MBBE; ++MBB) {
+ Start = lis_.getMBBStartIdx(MBB);
+ li_.addRange(LiveRange(Start, lis_.getMBBEndIdx(MBB),
+ mapValue(ParentVNI, Start)));
+ }
+
+ // Final block.
+ Start = lis_.getMBBStartIdx(MBB);
+ if (Start != End)
+ li_.addRange(LiveRange(Start, End, mapValue(ParentVNI, Start)));
+}
+
+/// addRange - Add live ranges to li_ where [Start;End) intersects parentli_.
+/// All needed values whose def is not inside [Start;End) must be defined
+/// beforehand so mapValue will work.
+void LiveIntervalMap::addRange(SlotIndex Start, SlotIndex End) {
+ LiveInterval::const_iterator B = parentli_.begin(), E = parentli_.end();
+ LiveInterval::const_iterator I = std::lower_bound(B, E, Start);
+
+ // Check if --I begins before Start and overlaps.
+ if (I != B) {
+ --I;
+ if (I->end > Start)
+ addSimpleRange(Start, std::min(End, I->end), I->valno);
+ ++I;
+ }
+
+ // The remaining ranges begin after Start.
+ for (;I != E && I->start < End; ++I)
+ addSimpleRange(I->start, std::min(End, I->end), I->valno);
+}
+
+//===----------------------------------------------------------------------===//
// Split Editor
//===----------------------------------------------------------------------===//
diff --git a/lib/CodeGen/SplitKit.h b/lib/CodeGen/SplitKit.h
index c419120a08..622d7e7749 100644
--- a/lib/CodeGen/SplitKit.h
+++ b/lib/CodeGen/SplitKit.h
@@ -20,6 +20,7 @@ namespace llvm {
class LiveInterval;
class LiveIntervals;
+class MachineDominatorTree;
class MachineInstr;
class MachineLoop;
class MachineLoopInfo;
@@ -135,6 +136,71 @@ public:
const MachineBasicBlock *getBlockForInsideSplit();
};
+
+/// LiveIntervalMap - Map values from a large LiveInterval into a small
+/// interval that is a subset. Insert phi-def values as needed. This class is
+/// used by SplitEditor to create new smaller LiveIntervals.
+///
+/// parentli_ is the larger interval, li_ is the subset interval. Every value
+/// in li_ corresponds to exactly one value in parentli_, and the live range
+/// of the value is contained within the live range of the parentli_ value.
+/// Values in parentli_ may map to any number of openli_ values, including 0.
+class LiveIntervalMap {
+ LiveIntervals &lis_;
+ MachineDominatorTree &dt_;
+
+ // The parent interval is never changed.
+ const LiveInterval &parentli_;
+
+ // The child interval's values are fully contained inside parentli_ values.
+ LiveInterval &li_;
+
+ typedef DenseMap<const VNInfo*, VNInfo*> ValueMap;
+
+ // Map parentli_ values to simple values in li_ that are defined at the same
+ // SlotIndex, or NULL for parentli_ values that have complex li_ defs.
+ // Note there is a difference between values mapping to NULL (complex), and
+ // values not present (unknown/unmapped).
+ ValueMap valueMap_;
+
+ // extendTo - Find the last li_ value defined in MBB at or before Idx. The
+ // parentli_ is assumed to be live at Idx. Extend the live range to Idx.
+ // Return the found VNInfo, or NULL.
+ VNInfo *extendTo(MachineBasicBlock *MBB, SlotIndex Idx);
+
+ // addSimpleRange - Add a simple range from parentli_ to li_.
+ // ParentVNI must be live in the [Start;End) interval.
+ void addSimpleRange(SlotIndex Start, SlotIndex End, const VNInfo *ParentVNI);
+
+public:
+ LiveIntervalMap(LiveIntervals &lis,
+ MachineDominatorTree &dt,
+ const LiveInterval &parentli,
+ LiveInterval &li)
+ : lis_(lis), dt_(dt), parentli_(parentli), li_(li) {}
+
+ /// defValue - define a value in li_ from the parentli_ value VNI and Idx.
+ /// Idx does not have to be ParentVNI->def, but it must be contained within
+ /// ParentVNI's live range in parentli_.
+ /// Return the new li_ value.
+ VNInfo *defValue(const VNInfo *ParentVNI, SlotIndex Idx);
+
+ /// mapValue - map ParentVNI to the corresponding li_ value at Idx. It is
+ /// assumed that ParentVNI is live at Idx.
+ /// If ParentVNI has not been defined by defValue, it is assumed that
+ /// ParentVNI->def dominates Idx.
+ /// If ParentVNI has been defined by defValue one or more times, a value that
+ /// dominates Idx will be returned. This may require creating extra phi-def
+ /// values and adding live ranges to li_.
+ VNInfo *mapValue(const VNInfo *ParentVNI, SlotIndex Idx);
+
+ /// addRange - Add live ranges to li_ where [Start;End) intersects parentli_.
+ /// All needed values whose def is not inside [Start;End) must be defined
+ /// beforehand so mapValue will work.
+ void addRange(SlotIndex Start, SlotIndex End);
+};
+
+
/// SplitEditor - Edit machine code and LiveIntervals for live range
/// splitting.
///
generated by cgit v1.2.3-18-g5258 (git 2.32.0) at 2025-08-05 15:42:13 +0000