[llvm] r184567 - Make rematerialization in the coalescer less sensitive to LRG order.
Andrew Trick
atrick at apple.com
Fri Jun 21 11:33:06 PDT 2013
Author: atrick
Date: Fri Jun 21 13:33:06 2013
New Revision: 184567
URL: http://llvm.org/viewvc/llvm-project?rev=184567&view=rev
Log:
Make rematerialization in the coalescer less sensitive to LRG order.
Modified:
llvm/trunk/lib/CodeGen/RegisterCoalescer.cpp
Modified: llvm/trunk/lib/CodeGen/RegisterCoalescer.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/RegisterCoalescer.cpp?rev=184567&r1=184566&r2=184567&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/RegisterCoalescer.cpp (original)
+++ llvm/trunk/lib/CodeGen/RegisterCoalescer.cpp Fri Jun 21 13:33:06 2013
@@ -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::removeCopyByComm
/// 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::reMaterializeTri
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(Machine
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(Machine
// 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.
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