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authorQuentin Colombet <qcolombet@apple.com>2015-03-27 18:37:15 +0000
committerQuentin Colombet <qcolombet@apple.com>2015-03-27 18:37:15 +0000
commit2e27df717a5989e299db95cd071ded1d21744a88 (patch)
treec5e0ff1c38cd775bcc976cbeac2edd357fc57597
parente2c61d9eece93cd6bc28b0af465d77097775cca4 (diff)
downloadbcm5719-llvm-2e27df717a5989e299db95cd071ded1d21744a88.tar.gz
bcm5719-llvm-2e27df717a5989e299db95cd071ded1d21744a88.zip
[RegisterCoalescer] Refine the terminal rule to still consider the terminal
nodes. When a node is terminal it is pushed at the end of the list of the copies to coalesce instead of being completely ignored. In effect, this reduces its priority over non-terminal nodes. Because of that, we do not miss the rematerialization opportunities, nor the copies that can be merged with more complex, than the terminal rule, interference checks. Related to PR22768. llvm-svn: 233395
-rw-r--r--llvm/lib/CodeGen/RegisterCoalescer.cpp40
-rw-r--r--llvm/test/CodeGen/X86/sret-implicit.ll2
2 files changed, 34 insertions, 8 deletions
diff --git a/llvm/lib/CodeGen/RegisterCoalescer.cpp b/llvm/lib/CodeGen/RegisterCoalescer.cpp
index 9e3cf415e44..c04437e21df 100644
--- a/llvm/lib/CodeGen/RegisterCoalescer.cpp
+++ b/llvm/lib/CodeGen/RegisterCoalescer.cpp
@@ -2733,13 +2733,17 @@ bool RegisterCoalescer::applyTerminalRule(const MachineInstr &Copy) const {
return false;
// Check if the destination of this copy has any other affinity.
unsigned DstReg = Copy.getOperand(0).getReg();
+ unsigned SrcReg = Copy.getOperand(1).getReg();
if (TargetRegisterInfo::isPhysicalRegister(DstReg) ||
+ // If SrcReg is a physical register, the copy won't be coalesced.
+ // Ignoring it may have other side effect (like missing
+ // rematerialization). So keep it.
+ TargetRegisterInfo::isPhysicalRegister(SrcReg) ||
!isTerminalReg(DstReg, Copy, MRI))
return false;
// DstReg is a terminal node. Check if it inteferes with any other
// copy involving SrcReg.
- unsigned SrcReg = Copy.getOperand(1).getReg();
const MachineBasicBlock *OrigBB = Copy.getParent();
const LiveInterval &DstLI = LIS->getInterval(DstReg);
for (const MachineInstr &MI : MRI->reg_nodbg_instructions(SrcReg)) {
@@ -2775,25 +2779,45 @@ RegisterCoalescer::copyCoalesceInMBB(MachineBasicBlock *MBB) {
// yet, it might invalidate the iterator.
const unsigned PrevSize = WorkList.size();
if (JoinGlobalCopies) {
+ SmallVector<MachineInstr*, 2> LocalTerminals;
+ SmallVector<MachineInstr*, 2> GlobalTerminals;
// Coalesce copies bottom-up to coalesce local defs before local uses. They
// are not inherently easier to resolve, but slightly preferable until we
// have local live range splitting. In particular this is required by
// cmp+jmp macro fusion.
for (MachineBasicBlock::iterator MII = MBB->begin(), E = MBB->end();
MII != E; ++MII) {
- if (!MII->isCopyLike() || applyTerminalRule(*MII))
+ if (!MII->isCopyLike())
continue;
- if (isLocalCopy(&(*MII), LIS))
- LocalWorkList.push_back(&(*MII));
- else
- WorkList.push_back(&(*MII));
+ bool ApplyTerminalRule = applyTerminalRule(*MII);
+ if (isLocalCopy(&(*MII), LIS)) {
+ if (ApplyTerminalRule)
+ LocalTerminals.push_back(&(*MII));
+ else
+ LocalWorkList.push_back(&(*MII));
+ } else {
+ if (ApplyTerminalRule)
+ GlobalTerminals.push_back(&(*MII));
+ else
+ WorkList.push_back(&(*MII));
+ }
}
+ // Append the copies evicted by the terminal rule at the end of the list.
+ LocalWorkList.append(LocalTerminals.begin(), LocalTerminals.end());
+ WorkList.append(GlobalTerminals.begin(), GlobalTerminals.end());
}
else {
+ SmallVector<MachineInstr*, 2> Terminals;
for (MachineBasicBlock::iterator MII = MBB->begin(), E = MBB->end();
MII != E; ++MII)
- if (MII->isCopyLike() && !applyTerminalRule(*MII))
- WorkList.push_back(MII);
+ if (MII->isCopyLike()) {
+ if (applyTerminalRule(*MII))
+ Terminals.push_back(&(*MII));
+ else
+ WorkList.push_back(MII);
+ }
+ // Append the copies evicted by the terminal rule at the end of the list.
+ WorkList.append(Terminals.begin(), Terminals.end());
}
// Try coalescing the collected copies immediately, and remove the nulls.
// This prevents the WorkList from getting too large since most copies are
diff --git a/llvm/test/CodeGen/X86/sret-implicit.ll b/llvm/test/CodeGen/X86/sret-implicit.ll
index 3fade1de0cf..56809525407 100644
--- a/llvm/test/CodeGen/X86/sret-implicit.ll
+++ b/llvm/test/CodeGen/X86/sret-implicit.ll
@@ -1,5 +1,7 @@
; RUN: llc -mtriple=x86_64-apple-darwin8 < %s | FileCheck %s
; RUN: llc -mtriple=x86_64-pc-linux < %s | FileCheck %s
+; RUN: llc -mtriple=x86_64-apple-darwin8 -terminal-rule < %s | FileCheck %s
+; RUN: llc -mtriple=x86_64-pc-linux -terminal-rule < %s | FileCheck %s
; CHECK-LABEL: return32
; CHECK-DAG: movq $0, (%rdi)
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