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-rw-r--r--lib/CodeGen/SimpleRegisterCoalescing.cpp110
-rw-r--r--lib/CodeGen/SimpleRegisterCoalescing.h3
2 files changed, 60 insertions, 53 deletions
diff --git a/lib/CodeGen/SimpleRegisterCoalescing.cpp b/lib/CodeGen/SimpleRegisterCoalescing.cpp
index 8c7eba9..93aa0a3 100644
--- a/lib/CodeGen/SimpleRegisterCoalescing.cpp
+++ b/lib/CodeGen/SimpleRegisterCoalescing.cpp
@@ -913,6 +913,50 @@ SimpleRegisterCoalescing::ShortenDeadCopySrcLiveRange(LiveInterval &li,
return removeIntervalIfEmpty(li, li_, tri_);
}
+/// shouldJoinPhys - Return true if a copy involving a physreg should be joined.
+/// We need to be careful about coalescing a source physical register with a
+/// virtual register. Once the coalescing is done, it cannot be broken and these
+/// are not spillable! If the destination interval uses are far away, think
+/// twice about coalescing them!
+bool SimpleRegisterCoalescing::shouldJoinPhys(CoalescerPair &CP) {
+ if (DisablePhysicalJoin) {
+ DEBUG(dbgs() << "\tPhysreg joins disabled.\n");
+ return false;
+ }
+
+ // Only coalesce to allocatable physreg.
+ if (!li_->isAllocatable(CP.getDstReg())) {
+ DEBUG(dbgs() << "\tRegister is an unallocatable physreg.\n");
+ return false; // Not coalescable.
+ }
+
+ // Don't join with physregs that have a ridiculous number of live
+ // ranges. The data structure performance is really bad when that
+ // happens.
+ if (li_->hasInterval(CP.getDstReg()) &&
+ li_->getInterval(CP.getDstReg()).ranges.size() > 1000) {
+ ++numAborts;
+ DEBUG(dbgs()
+ << "\tPhysical register live interval too complicated, abort!\n");
+ return false;
+ }
+
+ // FIXME: Why are we skipping this test for partial copies?
+ // CodeGen/X86/phys_subreg_coalesce-3.ll needs it.
+ if (!CP.isPartial()) {
+ LiveInterval &JoinVInt = li_->getInterval(CP.getSrcReg());
+
+ const TargetRegisterClass *RC = mri_->getRegClass(CP.getSrcReg());
+ unsigned Threshold = allocatableRCRegs_[RC].count() * 2;
+ unsigned Length = li_->getApproximateInstructionCount(JoinVInt);
+ if (Length > Threshold) {
+ ++numAborts;
+ DEBUG(dbgs() << "\tMay tie down a physical register, abort!\n");
+ return false;
+ }
+ }
+ return true;
+}
/// isWinToJoinCrossClass - Return true if it's profitable to coalesce
/// two virtual registers from different register classes.
@@ -985,27 +1029,25 @@ bool SimpleRegisterCoalescing::JoinCopy(CopyRec &TheCopy, bool &Again) {
return false; // Not coalescable.
}
- if (DisablePhysicalJoin && CP.isPhys()) {
- DEBUG(dbgs() << "\tPhysical joins disabled.\n");
- return false;
- }
-
- DEBUG(dbgs() << "\tConsidering merging " << PrintReg(CP.getSrcReg(), tri_));
+ DEBUG(dbgs() << "\tConsidering merging " << PrintReg(CP.getSrcReg(), tri_)
+ << " with " << PrintReg(CP.getDstReg(), tri_, CP.getSubIdx())
+ << "\n");
// Enforce policies.
if (CP.isPhys()) {
- DEBUG(dbgs() <<" with physreg " << PrintReg(CP.getDstReg(), tri_) << "\n");
- // Only coalesce to allocatable physreg.
- if (!li_->isAllocatable(CP.getDstReg())) {
- DEBUG(dbgs() << "\tRegister is an unallocatable physreg.\n");
- return false; // Not coalescable.
+ if (!shouldJoinPhys(CP)) {
+ // Before giving up coalescing, if definition of source is defined by
+ // trivial computation, try rematerializing it.
+ if (!CP.isFlipped() &&
+ ReMaterializeTrivialDef(li_->getInterval(CP.getSrcReg()), true,
+ CP.getDstReg(), 0, CopyMI))
+ return true;
+ return false;
}
} else {
- DEBUG(dbgs() << " with " << PrintReg(CP.getDstReg(), tri_, CP.getSubIdx())
- << " to " << CP.getNewRC()->getName() << "\n");
-
// Avoid constraining virtual register regclass too much.
if (CP.isCrossClass()) {
+ DEBUG(dbgs() << "\tCross-class to " << CP.getNewRC()->getName() << ".\n");
if (DisableCrossClassJoin) {
DEBUG(dbgs() << "\tCross-class joins disabled.\n");
return false;
@@ -1014,8 +1056,7 @@ bool SimpleRegisterCoalescing::JoinCopy(CopyRec &TheCopy, bool &Again) {
mri_->getRegClass(CP.getSrcReg()),
mri_->getRegClass(CP.getDstReg()),
CP.getNewRC())) {
- DEBUG(dbgs() << "\tAvoid coalescing to constrained register class: "
- << CP.getNewRC()->getName() << ".\n");
+ DEBUG(dbgs() << "\tAvoid coalescing to constrained register class.\n");
Again = true; // May be possible to coalesce later.
return false;
}
@@ -1027,43 +1068,6 @@ bool SimpleRegisterCoalescing::JoinCopy(CopyRec &TheCopy, bool &Again) {
CP.flip();
}
- // We need to be careful about coalescing a source physical register with a
- // virtual register. Once the coalescing is done, it cannot be broken and
- // these are not spillable! If the destination interval uses are far away,
- // think twice about coalescing them!
- // FIXME: Why are we skipping this test for partial copies?
- // CodeGen/X86/phys_subreg_coalesce-3.ll needs it.
- if (!CP.isPartial() && CP.isPhys()) {
- LiveInterval &JoinVInt = li_->getInterval(CP.getSrcReg());
-
- // Don't join with physregs that have a ridiculous number of live
- // ranges. The data structure performance is really bad when that
- // happens.
- if (li_->hasInterval(CP.getDstReg()) &&
- li_->getInterval(CP.getDstReg()).ranges.size() > 1000) {
- ++numAborts;
- DEBUG(dbgs()
- << "\tPhysical register live interval too complicated, abort!\n");
- return false;
- }
-
- const TargetRegisterClass *RC = mri_->getRegClass(CP.getSrcReg());
- unsigned Threshold = allocatableRCRegs_[RC].count() * 2;
- unsigned Length = li_->getApproximateInstructionCount(JoinVInt);
- if (Length > Threshold) {
- // Before giving up coalescing, if definition of source is defined by
- // trivial computation, try rematerializing it.
- if (!CP.isFlipped() &&
- ReMaterializeTrivialDef(JoinVInt, true, CP.getDstReg(), 0, CopyMI))
- return true;
-
- ++numAborts;
- DEBUG(dbgs() << "\tMay tie down a physical register, abort!\n");
- Again = true; // May be possible to coalesce later.
- return false;
- }
- }
-
// Okay, attempt to join these two intervals. On failure, this returns false.
// Otherwise, if one of the intervals being joined is a physreg, this method
// always canonicalizes DstInt to be it. The output "SrcInt" will not have
diff --git a/lib/CodeGen/SimpleRegisterCoalescing.h b/lib/CodeGen/SimpleRegisterCoalescing.h
index 6e79a40..65cf542 100644
--- a/lib/CodeGen/SimpleRegisterCoalescing.h
+++ b/lib/CodeGen/SimpleRegisterCoalescing.h
@@ -138,6 +138,9 @@ namespace llvm {
unsigned DstReg, unsigned DstSubIdx,
MachineInstr *CopyMI);
+ /// shouldJoinPhys - Return true if a physreg copy should be joined.
+ bool shouldJoinPhys(CoalescerPair &CP);
+
/// isWinToJoinCrossClass - Return true if it's profitable to coalesce
/// two virtual registers from different register classes.
bool isWinToJoinCrossClass(unsigned SrcReg,
generated by cgit v1.1 at 2024-12-25 07:16:46 +0000