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[RegAllocGreedy] Fix an assertion and condition when last chance recoloring is used.

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When last chance recoloring is used, the list of NewVRegs may not be
empty when calling selectOrSplitImpl. Indeed, another coloring may have
taken place with splitting/spilling in the same recoloring session.

Relax an assertion to take this into account and adapt a condition to
act as if the NewVRegs were local to this selectOrSplitImpl instance.

Unfortunately I am unable to produce a test case for this, I was only
able to reproduce the conditions on an out-of-tree target.

llvm-svn: 281782
This commit is contained in:
Quentin Colombet 2016-09-16 22:00:42 +00:00
parent d9bf037744
commit 9b569523e7
1 changed files with 3 additions and 2 deletions
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5
lib/CodeGen/RegAllocGreedy.cpp
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@ -2524,7 +2524,7 @@ unsigned RAGreedy::selectOrSplitImpl(LiveInterval &VirtReg,
return PhysReg;
}
assert(NewVRegs.empty() && "Cannot append to existing NewVRegs");
assert((NewVRegs.empty() || Depth) && "Cannot append to existing NewVRegs");
// The first time we see a live range, don't try to split or spill.
// Wait until the second time, when all smaller ranges have been allocated.
@ -2543,8 +2543,9 @@ unsigned RAGreedy::selectOrSplitImpl(LiveInterval &VirtReg,
Depth);
// Try splitting VirtReg or interferences.
unsigned NewVRegSizeBefore = NewVRegs.size();
unsigned PhysReg = trySplit(VirtReg, Order, NewVRegs);
if (PhysReg || !NewVRegs.empty())
if (PhysReg || (NewVRegs.size() - NewVRegSizeBefore))
return PhysReg;
// Finally spill VirtReg itself.