Author: hans
Date: Wed Feb 8 10:42:21 2017
New Revision: 294473
URL: http://llvm.org/viewvc/llvm-project?rev=294473&view=rev
Log:
MachineCopyPropagation: Respect implicit operands of COPY
Cherry pick llvm r294088 to 4.0 branch with slight changes to the way
undef operands are handled.
Modified:
llvm/branches/release_40/lib/CodeGen/MachineCopyPropagation.cpp
Modified: llvm/branches/release_40/lib/CodeGen/MachineCopyPropagation.cpp
URL:
http://llvm.org/viewvc/llvm-project/llvm/branches/release_40/lib/CodeGen/MachineCopyPropagation.cpp?rev=294473&r1=294472&r2=294473&view=diff
==============================================================================
--- llvm/branches/release_40/lib/CodeGen/MachineCopyPropagation.cpp (original)
+++ llvm/branches/release_40/lib/CodeGen/MachineCopyPropagation.cpp Wed Feb 8
10:42:21 2017
@@ -61,6 +61,7 @@ namespace {
private:
void ClobberRegister(unsigned Reg);
+ void ReadRegister(unsigned Reg);
void CopyPropagateBlock(MachineBasicBlock &MBB);
bool eraseIfRedundant(MachineInstr &Copy, unsigned Src, unsigned Def);
@@ -120,6 +121,18 @@ void MachineCopyPropagation::ClobberRegi
}
}
+void MachineCopyPropagation::ReadRegister(unsigned Reg) {
+ // If 'Reg' is defined by a copy, the copy is no longer a candidate
+ // for elimination.
+ for (MCRegAliasIterator AI(Reg, TRI, true); AI.isValid(); ++AI) {
+ Reg2MIMap::iterator CI = CopyMap.find(*AI);
+ if (CI != CopyMap.end()) {
+ DEBUG(dbgs() << "MCP: Copy is used - not dead: "; CI->second->dump());
+ MaybeDeadCopies.remove(CI->second);
+ }
+ }
+}
+
/// Return true if \p PreviousCopy did copy register \p Src to register \p Def.
/// This fact may have been obscured by sub register usage or may not be true
at
/// all even though Src and Def are subregisters of the registers used in
@@ -212,12 +225,14 @@ void MachineCopyPropagation::CopyPropaga
// If Src is defined by a previous copy, the previous copy cannot be
// eliminated.
- for (MCRegAliasIterator AI(Src, TRI, true); AI.isValid(); ++AI) {
- Reg2MIMap::iterator CI = CopyMap.find(*AI);
- if (CI != CopyMap.end()) {
- DEBUG(dbgs() << "MCP: Copy is no longer dead: "; CI->second->dump());
- MaybeDeadCopies.remove(CI->second);
- }
+ ReadRegister(Src);
+ for (const MachineOperand &MO : MI->implicit_operands()) {
+ if (!MO.isReg() || !MO.readsReg())
+ continue;
+ unsigned Reg = MO.getReg();
+ if (!Reg)
+ continue;
+ ReadRegister(Reg);
}
DEBUG(dbgs() << "MCP: Copy is a deletion candidate: "; MI->dump());
@@ -234,6 +249,14 @@ void MachineCopyPropagation::CopyPropaga
// ...
// %xmm2<def> = copy %xmm9
ClobberRegister(Def);
+ for (const MachineOperand &MO : MI->implicit_operands()) {
+ if (!MO.isReg() || !MO.isDef())
+ continue;
+ unsigned Reg = MO.getReg();
+ if (!Reg)
+ continue;
+ ClobberRegister(Reg);
+ }
// Remember Def is defined by the copy.
for (MCSubRegIterator SR(Def, TRI, /*IncludeSelf=*/true); SR.isValid();
@@ -268,17 +291,8 @@ void MachineCopyPropagation::CopyPropaga
if (MO.isDef()) {
Defs.push_back(Reg);
- continue;
- }
-
- // If 'Reg' is defined by a copy, the copy is no longer a candidate
- // for elimination.
- for (MCRegAliasIterator AI(Reg, TRI, true); AI.isValid(); ++AI) {
- Reg2MIMap::iterator CI = CopyMap.find(*AI);
- if (CI != CopyMap.end()) {
- DEBUG(dbgs() << "MCP: Copy is used - not dead: ";
CI->second->dump());
- MaybeDeadCopies.remove(CI->second);
- }
+ } else {
+ ReadRegister(Reg);
}
// Treat undef use like defs for copy propagation but not for
// dead copy. We would need to do a liveness check to be sure the copy
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