[llvm] r219584 - [X86] Memory folding for commutative instructions.
Simon Pilgrim
llvm-dev at redking.me.uk
Sun Oct 12 03:52:56 PDT 2014
Author: rksimon
Date: Sun Oct 12 05:52:55 2014
New Revision: 219584
URL: http://llvm.org/viewvc/llvm-project?rev=219584&view=rev
Log:
[X86] Memory folding for commutative instructions.
This patch improves support for commutative instructions in the x86 memory folding implementation by attempting to fold a commuted version of the instruction if the original folding fails - if that folding fails as well the instruction is 're-commuted' back to its original order before returning.
This mainly helps the stack inliner better fold reloads of 3 (or more) operand instructions (VEX encoded SSE etc.) but by performing this in the lowest foldMemoryOperandImpl implementation it also replaces the X86InstrInfo::optimizeLoadInstr version and is now used by FastISel too.
Differential Revision: http://reviews.llvm.org/D5701
Added:
llvm/trunk/test/CodeGen/X86/avx1-stack-reload-folding.ll
Modified:
llvm/trunk/lib/Target/X86/X86FastISel.cpp
llvm/trunk/lib/Target/X86/X86InstrInfo.cpp
llvm/trunk/lib/Target/X86/X86InstrInfo.h
Modified: llvm/trunk/lib/Target/X86/X86FastISel.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86FastISel.cpp?rev=219584&r1=219583&r2=219584&view=diff
==============================================================================
--- llvm/trunk/lib/Target/X86/X86FastISel.cpp (original)
+++ llvm/trunk/lib/Target/X86/X86FastISel.cpp Sun Oct 12 05:52:55 2014
@@ -3337,7 +3337,7 @@ bool X86FastISel::tryToFoldLoadIntoMI(Ma
AM.getFullAddress(AddrOps);
MachineInstr *Result =
- XII.foldMemoryOperandImpl(*FuncInfo.MF, MI, OpNo, AddrOps, Size, Alignment);
+ XII.foldMemoryOperandImpl(*FuncInfo.MF, MI, OpNo, AddrOps, Size, Alignment, /*AllowCommute=*/ true);
if (!Result)
return false;
Modified: llvm/trunk/lib/Target/X86/X86InstrInfo.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86InstrInfo.cpp?rev=219584&r1=219583&r2=219584&view=diff
==============================================================================
--- llvm/trunk/lib/Target/X86/X86InstrInfo.cpp (original)
+++ llvm/trunk/lib/Target/X86/X86InstrInfo.cpp Sun Oct 12 05:52:55 2014
@@ -3926,55 +3926,34 @@ optimizeLoadInstr(MachineInstr *MI, cons
if (!DefMI->isSafeToMove(this, nullptr, SawStore))
return nullptr;
- // We try to commute MI if possible.
- unsigned IdxEnd = (MI->isCommutable()) ? 2 : 1;
- for (unsigned Idx = 0; Idx < IdxEnd; Idx++) {
- // Collect information about virtual register operands of MI.
- unsigned SrcOperandId = 0;
- bool FoundSrcOperand = false;
- for (unsigned i = 0, e = MI->getDesc().getNumOperands(); i != e; ++i) {
- MachineOperand &MO = MI->getOperand(i);
- if (!MO.isReg())
- continue;
- unsigned Reg = MO.getReg();
- if (Reg != FoldAsLoadDefReg)
- continue;
- // Do not fold if we have a subreg use or a def or multiple uses.
- if (MO.getSubReg() || MO.isDef() || FoundSrcOperand)
- return nullptr;
-
- SrcOperandId = i;
- FoundSrcOperand = true;
- }
- if (!FoundSrcOperand) return nullptr;
-
- // Check whether we can fold the def into SrcOperandId.
- SmallVector<unsigned, 8> Ops;
- Ops.push_back(SrcOperandId);
- MachineInstr *FoldMI = foldMemoryOperand(MI, Ops, DefMI);
- if (FoldMI) {
- FoldAsLoadDefReg = 0;
- return FoldMI;
- }
-
- if (Idx == 1) {
- // MI was changed but it didn't help, commute it back!
- commuteInstruction(MI, false);
+ // Collect information about virtual register operands of MI.
+ unsigned SrcOperandId = 0;
+ bool FoundSrcOperand = false;
+ for (unsigned i = 0, e = MI->getDesc().getNumOperands(); i != e; ++i) {
+ MachineOperand &MO = MI->getOperand(i);
+ if (!MO.isReg())
+ continue;
+ unsigned Reg = MO.getReg();
+ if (Reg != FoldAsLoadDefReg)
+ continue;
+ // Do not fold if we have a subreg use or a def or multiple uses.
+ if (MO.getSubReg() || MO.isDef() || FoundSrcOperand)
return nullptr;
- }
- // Check whether we can commute MI and enable folding.
- if (MI->isCommutable()) {
- MachineInstr *NewMI = commuteInstruction(MI, false);
- // Unable to commute.
- if (!NewMI) return nullptr;
- if (NewMI != MI) {
- // New instruction. It doesn't need to be kept.
- NewMI->eraseFromParent();
- return nullptr;
- }
- }
+ SrcOperandId = i;
+ FoundSrcOperand = true;
+ }
+ if (!FoundSrcOperand) return nullptr;
+
+ // Check whether we can fold the def into SrcOperandId.
+ SmallVector<unsigned, 8> Ops;
+ Ops.push_back(SrcOperandId);
+ MachineInstr *FoldMI = foldMemoryOperand(MI, Ops, DefMI);
+ if (FoldMI) {
+ FoldAsLoadDefReg = 0;
+ return FoldMI;
}
+
return nullptr;
}
@@ -4134,7 +4113,7 @@ MachineInstr*
X86InstrInfo::foldMemoryOperandImpl(MachineFunction &MF,
MachineInstr *MI, unsigned i,
const SmallVectorImpl<MachineOperand> &MOs,
- unsigned Size, unsigned Align) const {
+ unsigned Size, unsigned Align, bool AllowCommute) const {
const DenseMap<unsigned,
std::pair<unsigned,unsigned> > *OpcodeTablePtr = nullptr;
bool isCallRegIndirect = Subtarget.callRegIndirect();
@@ -4231,6 +4210,46 @@ X86InstrInfo::foldMemoryOperandImpl(Mach
}
}
+ // If the instruction and target operand are commutable, commute the instruction and try again.
+ if (AllowCommute) {
+ unsigned OriginalOpIdx = i, CommuteOpIdx1, CommuteOpIdx2;
+ if (findCommutedOpIndices(MI, CommuteOpIdx1, CommuteOpIdx2)) {
+ if ((CommuteOpIdx1 == OriginalOpIdx) || (CommuteOpIdx2 == OriginalOpIdx)) {
+ MachineInstr* CommutedMI = commuteInstruction(MI, false);
+ if (!CommutedMI) {
+ // Unable to commute.
+ return nullptr;
+ }
+ if (CommutedMI != MI) {
+ // New instruction. We can't fold from this.
+ CommutedMI->eraseFromParent();
+ return nullptr;
+ }
+
+ // Attempt to fold with the commuted version of the instruction.
+ unsigned CommuteOpIdx = (CommuteOpIdx1 == OriginalOpIdx ? CommuteOpIdx2 : CommuteOpIdx1);
+ NewMI = foldMemoryOperandImpl(MF, MI, CommuteOpIdx, MOs, Size, Align, /*AllowCommute=*/ false);
+ if (NewMI)
+ return NewMI;
+
+ // Folding failed again - undo the commute before returning.
+ MachineInstr* UncommutedMI = commuteInstruction(MI, false);
+ if (!UncommutedMI) {
+ // Unable to commute.
+ return nullptr;
+ }
+ if (UncommutedMI != MI) {
+ // New instruction. It doesn't need to be kept.
+ UncommutedMI->eraseFromParent();
+ return nullptr;
+ }
+
+ // Return here to prevent duplicate fuse failure report.
+ return nullptr;
+ }
+ }
+ }
+
// No fusion
if (PrintFailedFusing && !MI->isCopy())
dbgs() << "We failed to fuse operand " << i << " in " << *MI;
@@ -4440,7 +4459,7 @@ X86InstrInfo::foldMemoryOperandImpl(Mach
SmallVector<MachineOperand,4> MOs;
MOs.push_back(MachineOperand::CreateFI(FrameIndex));
- return foldMemoryOperandImpl(MF, MI, Ops[0], MOs, Size, Alignment);
+ return foldMemoryOperandImpl(MF, MI, Ops[0], MOs, Size, Alignment, /*AllowCommute=*/ true);
}
static bool isPartialRegisterLoad(const MachineInstr &LoadMI,
@@ -4593,7 +4612,7 @@ MachineInstr* X86InstrInfo::foldMemoryOp
break;
}
}
- return foldMemoryOperandImpl(MF, MI, Ops[0], MOs, 0, Alignment);
+ return foldMemoryOperandImpl(MF, MI, Ops[0], MOs, 0, Alignment, /*AllowCommute=*/ true);
}
Modified: llvm/trunk/lib/Target/X86/X86InstrInfo.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86InstrInfo.h?rev=219584&r1=219583&r2=219584&view=diff
==============================================================================
--- llvm/trunk/lib/Target/X86/X86InstrInfo.h (original)
+++ llvm/trunk/lib/Target/X86/X86InstrInfo.h Sun Oct 12 05:52:55 2014
@@ -404,7 +404,7 @@ public:
MachineInstr* MI,
unsigned OpNum,
const SmallVectorImpl<MachineOperand> &MOs,
- unsigned Size, unsigned Alignment) const;
+ unsigned Size, unsigned Alignment, bool AllowCommute) const;
void
getUnconditionalBranch(MCInst &Branch,
Added: llvm/trunk/test/CodeGen/X86/avx1-stack-reload-folding.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/avx1-stack-reload-folding.ll?rev=219584&view=auto
==============================================================================
--- llvm/trunk/test/CodeGen/X86/avx1-stack-reload-folding.ll (added)
+++ llvm/trunk/test/CodeGen/X86/avx1-stack-reload-folding.ll Sun Oct 12 05:52:55 2014
@@ -0,0 +1,16 @@
+; RUN: llc -O3 -disable-peephole -mcpu=corei7-avx -mattr=+avx < %s | FileCheck %s
+
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-unknown"
+
+; Function Attrs: nounwind readonly uwtable
+define <32 x double> @_Z14vstack_foldDv32_dS_(<32 x double> %a, <32 x double> %b) #0 {
+ %1 = fadd <32 x double> %a, %b
+ %2 = fsub <32 x double> %a, %b
+ %3 = fmul <32 x double> %1, %2
+ ret <32 x double> %3
+
+ ;CHECK-NOT: vmovapd {{.*#+}} 32-byte Reload
+ ;CHECK: vmulpd {{[0-9]*}}(%rsp), {{%ymm[0-9][0-9]*}}, {{%ymm[0-9][0-9]*}} {{.*#+}} 32-byte Folded Reload
+ ;CHECK-NOT: vmovapd {{.*#+}} 32-byte Reload
+}
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