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Make rematerialization in the coalescer less sensitive to LRG order.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@184567 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Andrew Trick 2013-06-21 18:33:06 +00:00
parent 9b5575d55a
commit b5f906b98f
1 changed files with 15 additions and 4 deletions
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19
lib/CodeGen/RegisterCoalescer.cpp
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@ -166,7 +166,8 @@ namespace {
/// reMaterializeTrivialDef - If the source of a copy is defined by a
/// trivial computation, replace the copy by rematerialize the definition.
bool reMaterializeTrivialDef(CoalescerPair &CP, MachineInstr *CopyMI);
bool reMaterializeTrivialDef(CoalescerPair &CP, MachineInstr *CopyMI,
bool &IsDefCopy);
/// canJoinPhys - Return true if a physreg copy should be joined.
bool canJoinPhys(const CoalescerPair &CP);
@ -731,7 +732,9 @@ bool RegisterCoalescer::removeCopyByCommutingDef(const CoalescerPair &CP,
/// reMaterializeTrivialDef - If the source of a copy is defined by a trivial
/// computation, replace the copy by rematerialize the definition.
bool RegisterCoalescer::reMaterializeTrivialDef(CoalescerPair &CP,
MachineInstr *CopyMI) {
MachineInstr *CopyMI,
bool &IsDefCopy) {
IsDefCopy = false;
unsigned SrcReg = CP.isFlipped() ? CP.getDstReg() : CP.getSrcReg();
unsigned SrcIdx = CP.isFlipped() ? CP.getDstIdx() : CP.getSrcIdx();
unsigned DstReg = CP.isFlipped() ? CP.getSrcReg() : CP.getDstReg();
@ -750,6 +753,10 @@ bool RegisterCoalescer::reMaterializeTrivialDef(CoalescerPair &CP,
if (!DefMI)
return false;
assert(DefMI && "Defining instruction disappeared");
if (DefMI->isCopyLike()) {
IsDefCopy = true;
return false;
}
if (!DefMI->isAsCheapAsAMove())
return false;
if (!TII->isTriviallyReMaterializable(DefMI, AA))
@ -1064,8 +1071,11 @@ bool RegisterCoalescer::joinCopy(MachineInstr *CopyMI, bool &Again) {
if (!canJoinPhys(CP)) {
// Before giving up coalescing, if definition of source is defined by
// trivial computation, try rematerializing it.
if (reMaterializeTrivialDef(CP, CopyMI))
bool IsDefCopy;
if (reMaterializeTrivialDef(CP, CopyMI, IsDefCopy))
return true;
if (IsDefCopy)
Again = true; // May be possible to coalesce later.
return false;
}
} else {
@ -1097,7 +1107,8 @@ bool RegisterCoalescer::joinCopy(MachineInstr *CopyMI, bool &Again) {
// If definition of source is defined by trivial computation, try
// rematerializing it.
if (reMaterializeTrivialDef(CP, CopyMI))
bool IsDefCopy;
if (reMaterializeTrivialDef(CP, CopyMI, IsDefCopy))
return true;
// If we can eliminate the copy without merging the live ranges, do so now.