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EXTRACT_SUBREG coalescing support. The coalescer now treats EXTRACT_SUBREG like

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(almost) a register copy. However, it always coalesced to the register of the
RHS (the super-register). All uses of the result of a EXTRACT_SUBREG are sub-
register uses which adds subtle complications to load folding, spiller rewrite,
etc.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@42899 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Evan Cheng
2007-10-12 08:50:34 +00:00
parent 10136e7c7f
commit 32dfbeada7
12 changed files with 422 additions and 248 deletions
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13
lib/CodeGen/SelectionDAG/ScheduleDAGRRList.cpp
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@@ -1097,6 +1097,11 @@ namespace {
// CopyToReg should be close to its uses to facilitate coalescing and
// avoid spilling.
return 0;
else if (Opc == TargetInstrInfo::EXTRACT_SUBREG ||
Opc == TargetInstrInfo::INSERT_SUBREG)
// EXTRACT_SUBREG / INSERT_SUBREG should be close to its use to
// facilitate coalescing.
return 0;
else if (SU->NumSuccs == 0)
// If SU does not have a use, i.e. it doesn't produce a value that would
// be consumed (e.g. store), then it terminates a chain of computation.
@@ -1308,6 +1313,14 @@ void BURegReductionPriorityQueue<SF>::AddPseudoTwoAddrDeps() {
// Be conservative. Ignore if nodes aren't at the same depth.
if (SuccSU->Depth != SU->Depth)
continue;
if (!SuccSU->Node || !SuccSU->Node->isTargetOpcode())
continue;
// Don't constraint extract_subreg / insert_subreg these may be
// coalesced away. We don't them close to their uses.
unsigned SuccOpc = SuccSU->Node->getTargetOpcode();
if (SuccOpc == TargetInstrInfo::EXTRACT_SUBREG ||
SuccOpc == TargetInstrInfo::INSERT_SUBREG)
continue;
if ((!canClobber(SuccSU, DUSU) ||
(hasCopyToRegUse(SU) && !hasCopyToRegUse(SuccSU)) ||
(!SU->isCommutable && SuccSU->isCommutable)) &&