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Spill multiple registers at once.

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Live range splitting can create a number of small live ranges containing only a
single real use. Spill these small live ranges along with the large range they
are connected to with copies. This enables memory operand folding and maximizes
the spill to fill distance.

Work in progress with known bugs.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@127529 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Jakob Stoklund Olesen
2011-03-12 04:17:20 +00:00
parent 7a387e4d9d
commit 10a433238f
2 changed files with 210 additions and 48 deletions
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7
lib/CodeGen/RegAllocBasic.cpp
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@@ -289,6 +289,13 @@ void RegAllocBase::allocatePhysRegs() {
// Continue assigning vregs one at a time to available physical registers.
while (LiveInterval *VirtReg = dequeue()) {
// Unused registers can appear when the spiller coalesces snippets.
if (MRI->reg_nodbg_empty(VirtReg->reg)) {
DEBUG(dbgs() << "Dropping unused " << *VirtReg << '\n');
LIS->removeInterval(VirtReg->reg);
continue;
}
// selectOrSplit requests the allocator to return an available physical
// register if possible and populate a list of new live intervals that
// result from splitting.