[llvm] r189458 - [SystemZ] Extend memcmp support to all constant lengths
Richard Sandiford
rsandifo at linux.vnet.ibm.com
Wed Aug 28 02:01:51 PDT 2013
Author: rsandifo
Date: Wed Aug 28 04:01:51 2013
New Revision: 189458
URL: http://llvm.org/viewvc/llvm-project?rev=189458&view=rev
Log:
[SystemZ] Extend memcmp support to all constant lengths
This uses the infrastructure added for memcpy and memmove in r189331.
Modified:
llvm/trunk/lib/Target/SystemZ/SystemZISelLowering.cpp
llvm/trunk/lib/Target/SystemZ/SystemZSelectionDAGInfo.cpp
llvm/trunk/test/CodeGen/SystemZ/memcmp-01.ll
llvm/trunk/test/CodeGen/SystemZ/memcmp-02.ll
Modified: llvm/trunk/lib/Target/SystemZ/SystemZISelLowering.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/SystemZ/SystemZISelLowering.cpp?rev=189458&r1=189457&r2=189458&view=diff
==============================================================================
--- llvm/trunk/lib/Target/SystemZ/SystemZISelLowering.cpp (original)
+++ llvm/trunk/lib/Target/SystemZ/SystemZISelLowering.cpp Wed Aug 28 04:01:51 2013
@@ -1954,6 +1954,18 @@ static MachineBasicBlock *emitBlockAfter
return NewMBB;
}
+// Split MBB after MI and return the new block (the one that contains
+// instructions after MI).
+static MachineBasicBlock *splitBlockAfter(MachineInstr *MI,
+ MachineBasicBlock *MBB) {
+ MachineBasicBlock *NewMBB = emitBlockAfter(MBB);
+ NewMBB->splice(NewMBB->begin(), MBB,
+ llvm::next(MachineBasicBlock::iterator(MI)),
+ MBB->end());
+ NewMBB->transferSuccessorsAndUpdatePHIs(MBB);
+ return NewMBB;
+}
+
// Split MBB before MI and return the new block (the one that contains MI).
static MachineBasicBlock *splitBlockBefore(MachineInstr *MI,
MachineBasicBlock *MBB) {
@@ -2490,6 +2502,11 @@ SystemZTargetLowering::emitMemMemWrapper
uint64_t SrcDisp = MI->getOperand(3).getImm();
uint64_t Length = MI->getOperand(4).getImm();
+ // When generating more than one CLC, all but the last will need to
+ // branch to the end when a difference is found.
+ MachineBasicBlock *EndMBB = (Length > 256 && Opcode == SystemZ::CLC ?
+ splitBlockAfter(MI, MBB) : 0);
+
// Check for the loop form, in which operand 5 is the trip count.
if (MI->getNumExplicitOperands() > 5) {
bool HaveSingleBase = DestBase.isIdenticalTo(SrcBase);
@@ -2514,6 +2531,7 @@ SystemZTargetLowering::emitMemMemWrapper
MachineBasicBlock *StartMBB = MBB;
MachineBasicBlock *DoneMBB = splitBlockBefore(MI, MBB);
MachineBasicBlock *LoopMBB = emitBlockAfter(StartMBB);
+ MachineBasicBlock *NextMBB = (EndMBB ? emitBlockAfter(LoopMBB) : LoopMBB);
// StartMBB:
// # fall through to LoopMMB
@@ -2521,39 +2539,54 @@ SystemZTargetLowering::emitMemMemWrapper
// LoopMBB:
// %ThisDestReg = phi [ %StartDestReg, StartMBB ],
- // [ %NextDestReg, LoopMBB ]
+ // [ %NextDestReg, NextMBB ]
// %ThisSrcReg = phi [ %StartSrcReg, StartMBB ],
- // [ %NextSrcReg, LoopMBB ]
+ // [ %NextSrcReg, NextMBB ]
// %ThisCountReg = phi [ %StartCountReg, StartMBB ],
- // [ %NextCountReg, LoopMBB ]
- // PFD 2, 768+DestDisp(%ThisDestReg)
+ // [ %NextCountReg, NextMBB ]
+ // ( PFD 2, 768+DestDisp(%ThisDestReg) )
// Opcode DestDisp(256,%ThisDestReg), SrcDisp(%ThisSrcReg)
- // %NextDestReg = LA 256(%ThisDestReg)
- // %NextSrcReg = LA 256(%ThisSrcReg)
- // %NextCountReg = AGHI %ThisCountReg, -1
- // CGHI %NextCountReg, 0
- // JLH LoopMBB
- // # fall through to DoneMMB
+ // ( JLH EndMBB )
//
- // The AGHI, CGHI and JLH should be converted to BRCTG by later passes.
+ // The prefetch is used only for MVC. The JLH is used only for CLC.
MBB = LoopMBB;
BuildMI(MBB, DL, TII->get(SystemZ::PHI), ThisDestReg)
.addReg(StartDestReg).addMBB(StartMBB)
- .addReg(NextDestReg).addMBB(LoopMBB);
+ .addReg(NextDestReg).addMBB(NextMBB);
if (!HaveSingleBase)
BuildMI(MBB, DL, TII->get(SystemZ::PHI), ThisSrcReg)
.addReg(StartSrcReg).addMBB(StartMBB)
- .addReg(NextSrcReg).addMBB(LoopMBB);
+ .addReg(NextSrcReg).addMBB(NextMBB);
BuildMI(MBB, DL, TII->get(SystemZ::PHI), ThisCountReg)
.addReg(StartCountReg).addMBB(StartMBB)
- .addReg(NextCountReg).addMBB(LoopMBB);
- BuildMI(MBB, DL, TII->get(SystemZ::PFD))
- .addImm(SystemZ::PFD_WRITE)
- .addReg(ThisDestReg).addImm(DestDisp + 768).addReg(0);
+ .addReg(NextCountReg).addMBB(NextMBB);
+ if (Opcode == SystemZ::MVC)
+ BuildMI(MBB, DL, TII->get(SystemZ::PFD))
+ .addImm(SystemZ::PFD_WRITE)
+ .addReg(ThisDestReg).addImm(DestDisp + 768).addReg(0);
BuildMI(MBB, DL, TII->get(Opcode))
.addReg(ThisDestReg).addImm(DestDisp).addImm(256)
.addReg(ThisSrcReg).addImm(SrcDisp);
+ if (EndMBB) {
+ BuildMI(MBB, DL, TII->get(SystemZ::BRC))
+ .addImm(SystemZ::CCMASK_ICMP).addImm(SystemZ::CCMASK_CMP_NE)
+ .addMBB(EndMBB);
+ MBB->addSuccessor(EndMBB);
+ MBB->addSuccessor(NextMBB);
+ }
+
+ // NextMBB:
+ // %NextDestReg = LA 256(%ThisDestReg)
+ // %NextSrcReg = LA 256(%ThisSrcReg)
+ // %NextCountReg = AGHI %ThisCountReg, -1
+ // CGHI %NextCountReg, 0
+ // JLH LoopMBB
+ // # fall through to DoneMMB
+ //
+ // The AGHI, CGHI and JLH should be converted to BRCTG by later passes.
+ MBB = NextMBB;
+
BuildMI(MBB, DL, TII->get(SystemZ::LA), NextDestReg)
.addReg(ThisDestReg).addImm(256).addReg(0);
if (!HaveSingleBase)
@@ -2599,6 +2632,22 @@ SystemZTargetLowering::emitMemMemWrapper
DestDisp += ThisLength;
SrcDisp += ThisLength;
Length -= ThisLength;
+ // If there's another CLC to go, branch to the end if a difference
+ // was found.
+ if (EndMBB && Length > 0) {
+ MachineBasicBlock *NextMBB = splitBlockBefore(MI, MBB);
+ BuildMI(MBB, DL, TII->get(SystemZ::BRC))
+ .addImm(SystemZ::CCMASK_ICMP).addImm(SystemZ::CCMASK_CMP_NE)
+ .addMBB(EndMBB);
+ MBB->addSuccessor(EndMBB);
+ MBB->addSuccessor(NextMBB);
+ MBB = NextMBB;
+ }
+ }
+ if (EndMBB) {
+ MBB->addSuccessor(EndMBB);
+ MBB = EndMBB;
+ MBB->addLiveIn(SystemZ::CC);
}
MI->eraseFromParent();
Modified: llvm/trunk/lib/Target/SystemZ/SystemZSelectionDAGInfo.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/SystemZ/SystemZSelectionDAGInfo.cpp?rev=189458&r1=189457&r2=189458&view=diff
==============================================================================
--- llvm/trunk/lib/Target/SystemZ/SystemZSelectionDAGInfo.cpp (original)
+++ llvm/trunk/lib/Target/SystemZ/SystemZSelectionDAGInfo.cpp Wed Aug 28 04:01:51 2013
@@ -141,6 +141,28 @@ EmitTargetCodeForMemset(SelectionDAG &DA
return SDValue();
}
+// Use CLC to compare [Src1, Src1 + Size) with [Src2, Src2 + Size),
+// deciding whether to use a loop or straight-line code.
+static SDValue emitCLC(SelectionDAG &DAG, SDLoc DL, SDValue Chain,
+ SDValue Src1, SDValue Src2, uint64_t Size) {
+ SDVTList VTs = DAG.getVTList(MVT::Other, MVT::Glue);
+ EVT PtrVT = Src1.getValueType();
+ // A two-CLC sequence is a clear win over a loop, not least because it
+ // needs only one branch. A three-CLC sequence needs the same number
+ // of branches as a loop (i.e. 2), but is shorter. That brings us to
+ // lengths greater than 768 bytes. It seems relatively likely that
+ // a difference will be found within the first 768 bytes, so we just
+ // optimize for the smallest number of branch instructions, in order
+ // to avoid polluting the prediction buffer too much. A loop only ever
+ // needs 2 branches, whereas a straight-line sequence would need 3 or more.
+ if (Size > 3 * 256)
+ return DAG.getNode(SystemZISD::CLC_LOOP, DL, VTs, Chain, Src1, Src2,
+ DAG.getConstant(Size, PtrVT),
+ DAG.getConstant(Size / 256, PtrVT));
+ return DAG.getNode(SystemZISD::CLC, DL, VTs, Chain, Src1, Src2,
+ DAG.getConstant(Size, PtrVT));
+}
+
// Convert the current CC value into an integer that is 0 if CC == 0,
// less than zero if CC == 1 and greater than zero if CC >= 2.
// The sequence starts with IPM, which puts CC into bits 29 and 28
@@ -159,17 +181,12 @@ EmitTargetCodeForMemcmp(SelectionDAG &DA
SDValue Src1, SDValue Src2, SDValue Size,
MachinePointerInfo Op1PtrInfo,
MachinePointerInfo Op2PtrInfo) const {
- EVT PtrVT = Src1.getValueType();
if (ConstantSDNode *CSize = dyn_cast<ConstantSDNode>(Size)) {
uint64_t Bytes = CSize->getZExtValue();
- if (Bytes >= 1 && Bytes <= 0x100) {
- // A single CLC.
- SDVTList VTs = DAG.getVTList(MVT::Other, MVT::Glue);
- Chain = DAG.getNode(SystemZISD::CLC, DL, VTs, Chain,
- Src1, Src2, Size, DAG.getConstant(0, PtrVT));
- SDValue Glue = Chain.getValue(1);
- return std::make_pair(addIPMSequence(DL, Glue, DAG), Chain);
- }
+ assert(Bytes > 0 && "Caller should have handled 0-size case");
+ Chain = emitCLC(DAG, DL, Chain, Src1, Src2, Bytes);
+ SDValue Glue = Chain.getValue(1);
+ return std::make_pair(addIPMSequence(DL, Glue, DAG), Chain);
}
return std::make_pair(SDValue(), SDValue());
}
Modified: llvm/trunk/test/CodeGen/SystemZ/memcmp-01.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/SystemZ/memcmp-01.ll?rev=189458&r1=189457&r2=189458&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/SystemZ/memcmp-01.ll (original)
+++ llvm/trunk/test/CodeGen/SystemZ/memcmp-01.ll Wed Aug 28 04:01:51 2013
@@ -123,11 +123,99 @@ exit:
ret i32 %res
}
-; 257 bytes is too big for a single CLC. For now expect a call instead.
+; 257 bytes needs two CLCs.
define i32 @f8(i8 *%src1, i8 *%src2) {
; CHECK-LABEL: f8:
-; CHECK: brasl %r14, memcmp at PLT
+; CHECK: clc 0(256,%r2), 0(%r3)
+; CHECK: jlh [[LABEL:\..*]]
+; CHECK: clc 256(1,%r2), 256(%r3)
+; CHECK: [[LABEL]]:
+; CHECK: ipm [[REG:%r[0-5]]]
; CHECK: br %r14
%res = call i32 @memcmp(i8 *%src1, i8 *%src2, i64 257)
ret i32 %res
}
+
+; Test a comparison of 258 bytes in which the CC result can be used directly.
+define void @f9(i8 *%src1, i8 *%src2, i32 *%dest) {
+; CHECK-LABEL: f9:
+; CHECK: clc 0(256,%r2), 0(%r3)
+; CHECK: jlh [[LABEL:\..*]]
+; CHECK: clc 256(1,%r2), 256(%r3)
+; CHECK: [[LABEL]]:
+; CHECK-NEXT: jl .L
+; CHECK: br %r14
+entry:
+ %res = call i32 @memcmp(i8 *%src1, i8 *%src2, i64 257)
+ %cmp = icmp slt i32 %res, 0
+ br i1 %cmp, label %exit, label %store
+
+store:
+ store i32 0, i32 *%dest
+ br label %exit
+
+exit:
+ ret void
+}
+
+; Test the largest size that can use two CLCs.
+define i32 @f10(i8 *%src1, i8 *%src2) {
+; CHECK-LABEL: f10:
+; CHECK: clc 0(256,%r2), 0(%r3)
+; CHECK: jlh [[LABEL:\..*]]
+; CHECK: clc 256(256,%r2), 256(%r3)
+; CHECK: [[LABEL]]:
+; CHECK: ipm [[REG:%r[0-5]]]
+; CHECK: br %r14
+ %res = call i32 @memcmp(i8 *%src1, i8 *%src2, i64 512)
+ ret i32 %res
+}
+
+; Test the smallest size that needs 3 CLCs.
+define i32 @f11(i8 *%src1, i8 *%src2) {
+; CHECK-LABEL: f11:
+; CHECK: clc 0(256,%r2), 0(%r3)
+; CHECK: jlh [[LABEL:\..*]]
+; CHECK: clc 256(256,%r2), 256(%r3)
+; CHECK: jlh [[LABEL]]
+; CHECK: clc 512(1,%r2), 512(%r3)
+; CHECK: [[LABEL]]:
+; CHECK: ipm [[REG:%r[0-5]]]
+; CHECK: br %r14
+ %res = call i32 @memcmp(i8 *%src1, i8 *%src2, i64 513)
+ ret i32 %res
+}
+
+; Test the largest size than can use 3 CLCs.
+define i32 @f12(i8 *%src1, i8 *%src2) {
+; CHECK-LABEL: f12:
+; CHECK: clc 0(256,%r2), 0(%r3)
+; CHECK: jlh [[LABEL:\..*]]
+; CHECK: clc 256(256,%r2), 256(%r3)
+; CHECK: jlh [[LABEL]]
+; CHECK: clc 512(256,%r2), 512(%r3)
+; CHECK: [[LABEL]]:
+; CHECK: ipm [[REG:%r[0-5]]]
+; CHECK: br %r14
+ %res = call i32 @memcmp(i8 *%src1, i8 *%src2, i64 768)
+ ret i32 %res
+}
+
+; The next size up uses a loop instead. We leave the more complicated
+; loop tests to memcpy-01.ll, which shares the same form.
+define i32 @f13(i8 *%src1, i8 *%src2) {
+; CHECK-LABEL: f13:
+; CHECK: lghi [[COUNT:%r[0-5]]], 3
+; CHECK: [[LOOP:.L[^:]*]]:
+; CHECK: clc 0(256,%r2), 0(%r3)
+; CHECK: jlh [[LABEL:\..*]]
+; CHECK-DAG: la %r2, 256(%r2)
+; CHECK-DAG: la %r3, 256(%r3)
+; CHECK: brctg [[COUNT]], [[LOOP]]
+; CHECK: clc 0(1,%r2), 0(%r3)
+; CHECK: [[LABEL]]:
+; CHECK: ipm [[REG:%r[0-5]]]
+; CHECK: br %r14
+ %res = call i32 @memcmp(i8 *%src1, i8 *%src2, i64 769)
+ ret i32 %res
+}
Modified: llvm/trunk/test/CodeGen/SystemZ/memcmp-02.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/SystemZ/memcmp-02.ll?rev=189458&r1=189457&r2=189458&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/SystemZ/memcmp-02.ll (original)
+++ llvm/trunk/test/CodeGen/SystemZ/memcmp-02.ll Wed Aug 28 04:01:51 2013
@@ -125,10 +125,14 @@ exit:
ret i64 %res
}
-; 257 bytes is too big for a single CLC. For now expect a call instead.
+; 257 bytes needs two CLCs.
define i64 @f8(i8 *%src1, i8 *%src2) {
; CHECK-LABEL: f8:
-; CHECK: brasl %r14, memcmp at PLT
+; CHECK: clc 0(256,%r2), 0(%r3)
+; CHECK: jlh [[LABEL:\..*]]
+; CHECK: clc 256(1,%r2), 256(%r3)
+; CHECK: [[LABEL]]:
+; CHECK: ipm [[REG:%r[0-5]]]
; CHECK: br %r14
%res = call i64 @memcmp(i8 *%src1, i8 *%src2, i64 257)
ret i64 %res
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