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[PowerPC] using milicode call for strlen instead of lib call #153600

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[PowerPC] using milicode call for strlen instead of lib call #153600

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9f275a2
implement using milicode for strlen instead of libcall
diggerlin Aug 13, 2025
8ed02de
fix an error
diggerlin Aug 14, 2025
56fa506
address comment
diggerlin Aug 20, 2025
0c7f774
address comment
diggerlin Aug 22, 2025
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3 changes: 3 additions & 0 deletions llvm/include/llvm/CodeGen/SelectionDAG.h
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Expand Up @@ -1259,6 +1259,9 @@ class SelectionDAG {
std::pair<SDValue, SDValue> getMemcmp(SDValue Chain, const SDLoc &dl,
SDValue Dst, SDValue Src, SDValue Size,
const CallInst *CI);
LLVM_ABI std::pair<SDValue, SDValue>
getStrlen(SDValue Chain, const SDLoc &dl, SDValue Src, const CallInst *CI);

/* \p CI if not null is the memset call being lowered.
* \p OverrideTailCall is an optional parameter that can be used to override
* the tail call optimization decision. */
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2 changes: 1 addition & 1 deletion llvm/include/llvm/CodeGen/SelectionDAGTargetInfo.h
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Expand Up @@ -162,7 +162,7 @@ class SelectionDAGTargetInfo {

virtual std::pair<SDValue, SDValue>
EmitTargetCodeForStrlen(SelectionDAG &DAG, const SDLoc &DL, SDValue Chain,
SDValue Src, MachinePointerInfo SrcPtrInfo) const {
SDValue Src, const CallInst *CI) const {
return std::make_pair(SDValue(), SDValue());
}

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3 changes: 3 additions & 0 deletions llvm/include/llvm/IR/RuntimeLibcalls.td
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Expand Up @@ -282,6 +282,7 @@ def MEMMOVE : RuntimeLibcall;
def MEMSET : RuntimeLibcall;
def CALLOC : RuntimeLibcall;
def BZERO : RuntimeLibcall;
def STRLEN : RuntimeLibcall;

// Element-wise unordered-atomic memory of different sizes
foreach MemSize = [1, 2, 4, 8, 16] in {
Expand Down Expand Up @@ -2115,13 +2116,15 @@ defset list<RuntimeLibcallImpl> PPC64AIXCallList = {
def ___memmove64 : RuntimeLibcallImpl<MEMCPY>;
def ___memset64 : RuntimeLibcallImpl<MEMSET>;
def ___bzero64 : RuntimeLibcallImpl<BZERO>;
def ___strlen64 : RuntimeLibcallImpl<STRLEN>;
}

defset list<RuntimeLibcallImpl> PPC32AIXCallList = {
def ___memcmp : RuntimeLibcallImpl<MEMCMP>;
def ___memmove : RuntimeLibcallImpl<MEMMOVE>;
def ___memset : RuntimeLibcallImpl<MEMSET>;
def ___bzero : RuntimeLibcallImpl<BZERO>;
def ___strlen : RuntimeLibcallImpl<STRLEN>;
}

defvar PPCOverrides = !foreach(entry, PPCRuntimeLibcalls, entry.Provides);
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31 changes: 31 additions & 0 deletions llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
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Expand Up @@ -9050,6 +9050,37 @@ SelectionDAG::getMemcmp(SDValue Chain, const SDLoc &dl, SDValue Mem0,
return TLI->LowerCallTo(CLI);
}

std::pair<SDValue, SDValue> SelectionDAG::getStrlen(SDValue Chain,
const SDLoc &dl,
SDValue Src,
const CallInst *CI) {
const char *LibCallName = TLI->getLibcallName(RTLIB::STRLEN);
if (!LibCallName)
return {};

// Emit a library call.
auto GetEntry = [](Type *Ty, SDValue &SDV) {
TargetLowering::ArgListEntry E;
E.Ty = Ty;
E.Node = SDV;
return E;
};

PointerType *PT = PointerType::getUnqual(*getContext());
TargetLowering::ArgListTy Args = {GetEntry(PT, Src)};

TargetLowering::CallLoweringInfo CLI(*this);

// TODO: propagate tail call flag for targets where that is safe. Note
// that it is not safe on AIX which is the only current target.
Comment on lines +9074 to +9075
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I meant can you just factor out the existing check into a helper function that all the cases use

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I created an NFC patch [NFC ]Add a helper function isTailCall for getting libcall in SelectionDAG, After the NFC is approved, I will modify the patch accordingly.

CLI.setDebugLoc(dl).setChain(Chain).setLibCallee(
TLI->getLibcallCallingConv(RTLIB::STRLEN), CI->getType(),
getExternalSymbol(LibCallName, TLI->getProgramPointerTy(getDataLayout())),
std::move(Args));

return TLI->LowerCallTo(CLI);
}

SDValue SelectionDAG::getMemcpy(
SDValue Chain, const SDLoc &dl, SDValue Dst, SDValue Src, SDValue Size,
Align Alignment, bool isVol, bool AlwaysInline, const CallInst *CI,
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5 changes: 2 additions & 3 deletions llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
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Expand Up @@ -9287,9 +9287,8 @@ bool SelectionDAGBuilder::visitStrLenCall(const CallInst &I) {
const Value *Arg0 = I.getArgOperand(0);

const SelectionDAGTargetInfo &TSI = DAG.getSelectionDAGInfo();
std::pair<SDValue, SDValue> Res =
TSI.EmitTargetCodeForStrlen(DAG, getCurSDLoc(), DAG.getRoot(),
getValue(Arg0), MachinePointerInfo(Arg0));
std::pair<SDValue, SDValue> Res = TSI.EmitTargetCodeForStrlen(
DAG, getCurSDLoc(), DAG.getRoot(), getValue(Arg0), &I);
if (Res.first.getNode()) {
processIntegerCallValue(I, Res.first, false);
PendingLoads.push_back(Res.second);
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7 changes: 7 additions & 0 deletions llvm/lib/Target/PowerPC/PPCSelectionDAGInfo.cpp
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Expand Up @@ -28,3 +28,10 @@ std::pair<SDValue, SDValue> PPCSelectionDAGInfo::EmitTargetCodeForMemcmp(
SDValue Op3, const CallInst *CI) const {
return DAG.getMemcmp(Chain, dl, Op1, Op2, Op3, CI);
}

std::pair<SDValue, SDValue>
PPCSelectionDAGInfo::EmitTargetCodeForStrlen(SelectionDAG &DAG, const SDLoc &DL,
SDValue Chain, SDValue Src,
const CallInst *CI) const {
return DAG.getStrlen(Chain, DL, Src, CI);
}
3 changes: 3 additions & 0 deletions llvm/lib/Target/PowerPC/PPCSelectionDAGInfo.h
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Expand Up @@ -25,6 +25,9 @@ class PPCSelectionDAGInfo : public SelectionDAGTargetInfo {
EmitTargetCodeForMemcmp(SelectionDAG &DAG, const SDLoc &dl, SDValue Chain,
SDValue Op1, SDValue Op2, SDValue Op3,
const CallInst *CI) const override;
std::pair<SDValue, SDValue>
EmitTargetCodeForStrlen(SelectionDAG &DAG, const SDLoc &DL, SDValue Chain,
SDValue Src, const CallInst *CI) const override;
};

} // namespace llvm
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2 changes: 1 addition & 1 deletion llvm/lib/Target/SystemZ/SystemZSelectionDAGInfo.cpp
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Expand Up @@ -263,7 +263,7 @@ static std::pair<SDValue, SDValue> getBoundedStrlen(SelectionDAG &DAG,

std::pair<SDValue, SDValue> SystemZSelectionDAGInfo::EmitTargetCodeForStrlen(
SelectionDAG &DAG, const SDLoc &DL, SDValue Chain, SDValue Src,
MachinePointerInfo SrcPtrInfo) const {
const CallInst *CI) const {
EVT PtrVT = Src.getValueType();
return getBoundedStrlen(DAG, DL, Chain, Src, DAG.getConstant(0, DL, PtrVT));
}
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3 changes: 1 addition & 2 deletions llvm/lib/Target/SystemZ/SystemZSelectionDAGInfo.h
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Expand Up @@ -61,8 +61,7 @@ class SystemZSelectionDAGInfo : public SelectionDAGTargetInfo {

std::pair<SDValue, SDValue>
EmitTargetCodeForStrlen(SelectionDAG &DAG, const SDLoc &DL, SDValue Chain,
SDValue Src,
MachinePointerInfo SrcPtrInfo) const override;
SDValue Src, const CallInst *CI) const override;

std::pair<SDValue, SDValue>
EmitTargetCodeForStrnlen(SelectionDAG &DAG, const SDLoc &DL, SDValue Chain,
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2 changes: 1 addition & 1 deletion llvm/test/CodeGen/PowerPC/milicode32.ll
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Expand Up @@ -42,7 +42,7 @@ define i32 @strlen_test(ptr noundef %str) nounwind {
; CHECK-AIX-32-P9-NEXT: stwu r1, -64(r1)
; CHECK-AIX-32-P9-NEXT: stw r0, 72(r1)
; CHECK-AIX-32-P9-NEXT: stw r3, 60(r1)
; CHECK-AIX-32-P9-NEXT: bl .strlen[PR]
; CHECK-AIX-32-P9-NEXT: bl .___strlen[PR]
; CHECK-AIX-32-P9-NEXT: nop
; CHECK-AIX-32-P9-NEXT: addi r1, r1, 64
; CHECK-AIX-32-P9-NEXT: lwz r0, 8(r1)
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2 changes: 1 addition & 1 deletion llvm/test/CodeGen/PowerPC/milicode64.ll
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Expand Up @@ -85,7 +85,7 @@ define i64 @strlen_test(ptr noundef %str) nounwind {
; CHECK-AIX-64-P9-NEXT: stdu r1, -128(r1)
; CHECK-AIX-64-P9-NEXT: std r0, 144(r1)
; CHECK-AIX-64-P9-NEXT: std r3, 120(r1)
; CHECK-AIX-64-P9-NEXT: bl .strlen[PR]
; CHECK-AIX-64-P9-NEXT: bl .___strlen64[PR]
; CHECK-AIX-64-P9-NEXT: nop
; CHECK-AIX-64-P9-NEXT: addi r1, r1, 128
; CHECK-AIX-64-P9-NEXT: ld r0, 16(r1)
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