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Add SplitEditor::overlapIntv() to create small ranges where both registers are live.

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If a live range is used by a terminator instruction, and that live range needs
to leave the block on the stack or in a different register, it can be necessary
to have both sides of the split live at the terminator instruction.

Example:

  %vreg2 = COPY %vreg1
  JMP %vreg1

Becomes after spilling %vreg2:

  SPILL %vreg1
  JMP %vreg1

The spill doesn't kill the register as is normally the case.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@125102 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Jakob Stoklund Olesen
2011-02-08 18:50:21 +00:00
parent 01cb34b011
commit 5c716bdccc
3 changed files with 53 additions and 2 deletions
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lib/CodeGen/SplitKit.cpp
+16
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@@ -882,6 +882,22 @@ SlotIndex SplitEditor::leaveIntvAtTop(MachineBasicBlock &MBB) {
return VNI->def;
}
void SplitEditor::overlapIntv(SlotIndex Start, SlotIndex End) {
assert(OpenIdx && "openIntv not called before overlapIntv");
assert(Edit.getParent().getVNInfoAt(Start) ==
Edit.getParent().getVNInfoAt(End.getPrevSlot()) &&
"Parent changes value in extended range");
assert(Edit.get(0)->getVNInfoAt(Start) && "Start must come from leaveIntv*");
assert(LIS.getMBBFromIndex(Start) == LIS.getMBBFromIndex(End) &&
"Range cannot span basic blocks");
// Treat this as useIntv() for now. The complement interval will be extended
// as needed by mapValue().
DEBUG(dbgs() << " overlapIntv [" << Start << ';' << End << "):");
RegAssign.insert(Start, End, OpenIdx);
DEBUG(dump());
}
/// closeIntv - Indicate that we are done editing the currently open
/// LiveInterval, and ranges can be trimmed.
void SplitEditor::closeIntv() {