[llvm-commits] [llvm] r108304 - in /llvm/trunk: include/llvm/CodeGen/ProcessImplicitDefs.h lib/CodeGen/MachineLICM.cpp lib/CodeGen/ProcessImplicitDefs.cpp test/CodeGen/X86/2009-02-26-MachineLICMBug.ll
Evan Cheng
evan.cheng at apple.com
Tue Jul 13 18:22:19 PDT 2010
Author: evancheng
Date: Tue Jul 13 20:22:19 2010
New Revision: 108304
URL: http://llvm.org/viewvc/llvm-project?rev=108304&view=rev
Log:
Teach ProcessImplicitDefs to transform more COPY instructions into IMPLICIT_DEF (and subsequently eliminate them). This allows machine LICM to hoist IMPLICIT_DEF's. PR7620.
Modified:
llvm/trunk/include/llvm/CodeGen/ProcessImplicitDefs.h
llvm/trunk/lib/CodeGen/MachineLICM.cpp
llvm/trunk/lib/CodeGen/ProcessImplicitDefs.cpp
llvm/trunk/test/CodeGen/X86/2009-02-26-MachineLICMBug.ll
Modified: llvm/trunk/include/llvm/CodeGen/ProcessImplicitDefs.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/CodeGen/ProcessImplicitDefs.h?rev=108304&r1=108303&r2=108304&view=diff
==============================================================================
--- llvm/trunk/include/llvm/CodeGen/ProcessImplicitDefs.h (original)
+++ llvm/trunk/include/llvm/CodeGen/ProcessImplicitDefs.h Tue Jul 13 20:22:19 2010
@@ -12,6 +12,7 @@
#define LLVM_CODEGEN_PROCESSIMPLICITDEFS_H
#include "llvm/CodeGen/MachineFunctionPass.h"
+#include "llvm/ADT/SmallSet.h"
namespace llvm {
@@ -24,7 +25,8 @@
private:
bool CanTurnIntoImplicitDef(MachineInstr *MI, unsigned Reg,
- unsigned OpIdx, const TargetInstrInfo *tii_);
+ unsigned OpIdx, const TargetInstrInfo *tii_,
+ SmallSet<unsigned, 8> &ImpDefRegs);
public:
static char ID;
Modified: llvm/trunk/lib/CodeGen/MachineLICM.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/MachineLICM.cpp?rev=108304&r1=108303&r2=108304&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/MachineLICM.cpp (original)
+++ llvm/trunk/lib/CodeGen/MachineLICM.cpp Tue Jul 13 20:22:19 2010
@@ -497,11 +497,6 @@
/// candidate for LICM. e.g. If the instruction is a call, then it's obviously
/// not safe to hoist it.
bool MachineLICM::IsLICMCandidate(MachineInstr &I) {
- // It is not profitable to hoist implicitdefs. FIXME: Why not? what if they
- // are an argument to some other otherwise-hoistable instruction?
- if (I.isImplicitDef())
- return false;
-
// Check if it's safe to move the instruction.
bool DontMoveAcrossStore = true;
if (!I.isSafeToMove(TII, AA, DontMoveAcrossStore))
@@ -717,7 +712,9 @@
bool MachineLICM::EliminateCSE(MachineInstr *MI,
DenseMap<unsigned, std::vector<const MachineInstr*> >::iterator &CI) {
- if (CI == CSEMap.end())
+ // Do not CSE implicit_def so ProcessImplicitDefs can properly propagate
+ // the undef property onto uses.
+ if (CI == CSEMap.end() || MI->isImplicitDef())
return false;
if (const MachineInstr *Dup = LookForDuplicate(MI, CI->second)) {
Modified: llvm/trunk/lib/CodeGen/ProcessImplicitDefs.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/ProcessImplicitDefs.cpp?rev=108304&r1=108303&r2=108304&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/ProcessImplicitDefs.cpp (original)
+++ llvm/trunk/lib/CodeGen/ProcessImplicitDefs.cpp Tue Jul 13 20:22:19 2010
@@ -41,21 +41,51 @@
MachineFunctionPass::getAnalysisUsage(AU);
}
-bool ProcessImplicitDefs::CanTurnIntoImplicitDef(MachineInstr *MI,
- unsigned Reg, unsigned OpIdx,
- const TargetInstrInfo *tii_) {
+bool
+ProcessImplicitDefs::CanTurnIntoImplicitDef(MachineInstr *MI,
+ unsigned Reg, unsigned OpIdx,
+ const TargetInstrInfo *tii_,
+ SmallSet<unsigned, 8> &ImpDefRegs) {
unsigned SrcReg, DstReg, SrcSubReg, DstSubReg;
if (tii_->isMoveInstr(*MI, SrcReg, DstReg, SrcSubReg, DstSubReg) &&
- Reg == SrcReg && DstSubReg == 0)
+ Reg == SrcReg &&
+ (DstSubReg == 0 || ImpDefRegs.count(DstReg)))
return true;
switch(OpIdx) {
- case 1: return MI->isCopy() && MI->getOperand(0).getSubReg() == 0;
- case 2: return MI->isSubregToReg() && MI->getOperand(0).getSubReg() == 0;
- default: return false;
+ case 1:
+ return MI->isCopy() && (MI->getOperand(0).getSubReg() == 0 ||
+ ImpDefRegs.count(MI->getOperand(0).getReg()));
+ case 2:
+ return MI->isSubregToReg() && (MI->getOperand(0).getSubReg() == 0 ||
+ ImpDefRegs.count(MI->getOperand(0).getReg()));
+ default: return false;
}
}
+static bool isUndefCopy(MachineInstr *MI, unsigned Reg,
+ const TargetInstrInfo *tii_,
+ SmallSet<unsigned, 8> &ImpDefRegs) {
+ if (MI->isCopy()) {
+ MachineOperand &MO0 = MI->getOperand(0);
+ MachineOperand &MO1 = MI->getOperand(1);
+ if (MO1.getReg() != Reg)
+ return false;
+ if (!MO0.getSubReg() || ImpDefRegs.count(MO0.getReg()))
+ return true;
+ return false;
+ }
+
+ unsigned SrcReg, DstReg, SrcSubReg, DstSubReg;
+ if (tii_->isMoveInstr(*MI, SrcReg, DstReg, SrcSubReg, DstSubReg)) {
+ if (Reg != SrcReg)
+ return false;
+ if (DstSubReg == 0 || ImpDefRegs.count(DstReg))
+ return true;
+ }
+ return false;
+}
+
/// processImplicitDefs - Process IMPLICIT_DEF instructions and make sure
/// there is one implicit_def for each use. Add isUndef marker to
/// implicit_def defs and their uses.
@@ -104,7 +134,7 @@
// Eliminate %reg1032:sub<def> = COPY undef.
if (MI->isCopy() && MI->getOperand(0).getSubReg()) {
MachineOperand &MO = MI->getOperand(1);
- if (ImpDefRegs.count(MO.getReg())) {
+ if (MO.isUndef() || ImpDefRegs.count(MO.getReg())) {
if (MO.isKill()) {
LiveVariables::VarInfo& vi = lv_->getVarInfo(MO.getReg());
vi.removeKill(MI);
@@ -126,7 +156,7 @@
if (!ImpDefRegs.count(Reg))
continue;
// Use is a copy, just turn it into an implicit_def.
- if (CanTurnIntoImplicitDef(MI, Reg, i, tii_)) {
+ if (CanTurnIntoImplicitDef(MI, Reg, i, tii_, ImpDefRegs)) {
bool isKill = MO.isKill();
MI->setDesc(tii_->get(TargetOpcode::IMPLICIT_DEF));
for (int j = MI->getNumOperands() - 1, ee = 0; j > ee; --j)
@@ -223,11 +253,7 @@
MachineInstr *RMI = RUses[i];
// Turn a copy use into an implicit_def.
- unsigned SrcReg, DstReg, SrcSubReg, DstSubReg;
- if ((RMI->isCopy() && RMI->getOperand(1).getReg() == Reg &&
- RMI->getOperand(0).getSubReg() == 0) ||
- (tii_->isMoveInstr(*RMI, SrcReg, DstReg, SrcSubReg, DstSubReg) &&
- Reg == SrcReg && DstSubReg == 0)) {
+ if (isUndefCopy(RMI, Reg, tii_, ImpDefRegs)) {
RMI->setDesc(tii_->get(TargetOpcode::IMPLICIT_DEF));
bool isKill = false;
Modified: llvm/trunk/test/CodeGen/X86/2009-02-26-MachineLICMBug.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/2009-02-26-MachineLICMBug.ll?rev=108304&r1=108303&r2=108304&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/X86/2009-02-26-MachineLICMBug.ll (original)
+++ llvm/trunk/test/CodeGen/X86/2009-02-26-MachineLICMBug.ll Tue Jul 13 20:22:19 2010
@@ -1,4 +1,4 @@
-; RUN: llc < %s -march=x86-64 -mattr=+sse3 -stats |& grep {2 machine-licm}
+; RUN: llc < %s -march=x86-64 -mattr=+sse3 -stats |& grep {7 machine-licm}
; RUN: llc < %s -march=x86-64 -mattr=+sse3 | FileCheck %s
; rdar://6627786
; rdar://7792037
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