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If the source and destination pointers in an llvm.memmove are known 

to not alias each other, it can be translated as an llvm.memcpy.

llvm-svn: 41489
This commit is contained in:
Dan Gohman 2007-08-27 16:26:13 +00:00
parent 71eaf62e5f
commit 8dc0b93151
6 changed files with 62 additions and 12 deletions
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1
llvm/include/llvm/CodeGen/SelectionDAGISel.h
View File

@ -39,6 +39,7 @@ public:
SSARegMap *RegMap;
SelectionDAG *CurDAG;
MachineBasicBlock *BB;
AliasAnalysis *AA;
std::vector<SDNode*> TopOrder;
unsigned DAGSize;
static char ID;

37
llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
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@ -409,6 +409,7 @@ public:
TargetLowering &TLI;
SelectionDAG &DAG;
const TargetData *TD;
AliasAnalysis &AA;
/// SwitchCases - Vector of CaseBlock structures used to communicate
/// SwitchInst code generation information.
@ -423,8 +424,9 @@ public:
FunctionLoweringInfo &FuncInfo;
SelectionDAGLowering(SelectionDAG &dag, TargetLowering &tli,
AliasAnalysis &aa,
FunctionLoweringInfo &funcinfo)
: TLI(tli), DAG(dag), TD(DAG.getTarget().getTargetData()),
: TLI(tli), DAG(dag), TD(DAG.getTarget().getTargetData()), AA(aa),
FuncInfo(funcinfo) {
}
@ -4196,6 +4198,17 @@ void SelectionDAGLowering::visitMemIntrinsic(CallInst &I, unsigned Op) {
unsigned Align = (unsigned)cast<ConstantSDNode>(Op4)->getValue();
if (Align == 0) Align = 1;
// If the source and destination are known to not be aliases, we can
// lower memmove as memcpy.
if (Op == ISD::MEMMOVE) {
uint64_t Size = -1;
if (ConstantSDNode *C = dyn_cast<ConstantSDNode>(Op3))
Size = C->getValue();
if (AA.alias(I.getOperand(1), Size, I.getOperand(2), Size) ==
AliasAnalysis::NoAlias)
Op = ISD::MEMCPY;
}
if (ConstantSDNode *Size = dyn_cast<ConstantSDNode>(Op3)) {
std::vector<MVT::ValueType> MemOps;
@ -4307,6 +4320,9 @@ void SelectionDAGISel::getAnalysisUsage(AnalysisUsage &AU) const {
bool SelectionDAGISel::runOnFunction(Function &Fn) {
// Get alias analysis for load/store combining.
AA = &getAnalysis<AliasAnalysis>();
MachineFunction &MF = MachineFunction::construct(&Fn, TLI.getTargetMachine());
RegMap = MF.getSSARegMap();
DOUT << "\n\n\n=== " << Fn.getName() << "\n";
@ -4404,7 +4420,7 @@ static void copyCatchInfo(BasicBlock *SrcBB, BasicBlock *DestBB,
void SelectionDAGISel::BuildSelectionDAG(SelectionDAG &DAG, BasicBlock *LLVMBB,
std::vector<std::pair<MachineInstr*, unsigned> > &PHINodesToUpdate,
FunctionLoweringInfo &FuncInfo) {
SelectionDAGLowering SDL(DAG, TLI, FuncInfo);
SelectionDAGLowering SDL(DAG, TLI, *AA, FuncInfo);
std::vector<SDOperand> UnorderedChains;
@ -4581,11 +4597,8 @@ void SelectionDAGISel::BuildSelectionDAG(SelectionDAG &DAG, BasicBlock *LLVMBB,
}
void SelectionDAGISel::CodeGenAndEmitDAG(SelectionDAG &DAG) {
// Get alias analysis for load/store combining.
AliasAnalysis &AA = getAnalysis<AliasAnalysis>();
// Run the DAG combiner in pre-legalize mode.
DAG.Combine(false, AA);
DAG.Combine(false, *AA);
DOUT << "Lowered selection DAG:\n";
DEBUG(DAG.dump());
@ -4598,7 +4611,7 @@ void SelectionDAGISel::CodeGenAndEmitDAG(SelectionDAG &DAG) {
DEBUG(DAG.dump());
// Run the DAG combiner in post-legalize mode.
DAG.Combine(true, AA);
DAG.Combine(true, *AA);
if (ViewISelDAGs) DAG.viewGraph();
@ -4649,7 +4662,7 @@ void SelectionDAGISel::SelectBasicBlock(BasicBlock *LLVMBB, MachineFunction &MF,
if (!BitTestCases[i].Emitted) {
SelectionDAG HSDAG(TLI, MF, getAnalysisToUpdate<MachineModuleInfo>());
CurDAG = &HSDAG;
SelectionDAGLowering HSDL(HSDAG, TLI, FuncInfo);
SelectionDAGLowering HSDL(HSDAG, TLI, *AA, FuncInfo);
// Set the current basic block to the mbb we wish to insert the code into
BB = BitTestCases[i].Parent;
HSDL.setCurrentBasicBlock(BB);
@ -4662,7 +4675,7 @@ void SelectionDAGISel::SelectBasicBlock(BasicBlock *LLVMBB, MachineFunction &MF,
for (unsigned j = 0, ej = BitTestCases[i].Cases.size(); j != ej; ++j) {
SelectionDAG BSDAG(TLI, MF, getAnalysisToUpdate<MachineModuleInfo>());
CurDAG = &BSDAG;
SelectionDAGLowering BSDL(BSDAG, TLI, FuncInfo);
SelectionDAGLowering BSDL(BSDAG, TLI, *AA, FuncInfo);
// Set the current basic block to the mbb we wish to insert the code into
BB = BitTestCases[i].Cases[j].ThisBB;
BSDL.setCurrentBasicBlock(BB);
@ -4715,7 +4728,7 @@ void SelectionDAGISel::SelectBasicBlock(BasicBlock *LLVMBB, MachineFunction &MF,
if (!JTCases[i].first.Emitted) {
SelectionDAG HSDAG(TLI, MF, getAnalysisToUpdate<MachineModuleInfo>());
CurDAG = &HSDAG;
SelectionDAGLowering HSDL(HSDAG, TLI, FuncInfo);
SelectionDAGLowering HSDL(HSDAG, TLI, *AA, FuncInfo);
// Set the current basic block to the mbb we wish to insert the code into
BB = JTCases[i].first.HeaderBB;
HSDL.setCurrentBasicBlock(BB);
@ -4727,7 +4740,7 @@ void SelectionDAGISel::SelectBasicBlock(BasicBlock *LLVMBB, MachineFunction &MF,
SelectionDAG JSDAG(TLI, MF, getAnalysisToUpdate<MachineModuleInfo>());
CurDAG = &JSDAG;
SelectionDAGLowering JSDL(JSDAG, TLI, FuncInfo);
SelectionDAGLowering JSDL(JSDAG, TLI, *AA, FuncInfo);
// Set the current basic block to the mbb we wish to insert the code into
BB = JTCases[i].second.MBB;
JSDL.setCurrentBasicBlock(BB);
@ -4772,7 +4785,7 @@ void SelectionDAGISel::SelectBasicBlock(BasicBlock *LLVMBB, MachineFunction &MF,
for (unsigned i = 0, e = SwitchCases.size(); i != e; ++i) {
SelectionDAG SDAG(TLI, MF, getAnalysisToUpdate<MachineModuleInfo>());
CurDAG = &SDAG;
SelectionDAGLowering SDL(SDAG, TLI, FuncInfo);
SelectionDAGLowering SDL(SDAG, TLI, *AA, FuncInfo);
// Set the current basic block to the mbb we wish to insert the code into
BB = SwitchCases[i].ThisBB;

9
llvm/test/CodeGen/X86/memmove-0.ll Normal file
View File

@ -0,0 +1,9 @@
; RUN: llvm-as < %s | llc -march=x86 | grep {call memcpy}
declare void @llvm.memmove.i64(i8* %d, i8* %s, i64 %l, i32 %a)
define void @foo(i8* noalias %d, i8* noalias %s, i64 %l)
{
call void @llvm.memmove.i64(i8* %d, i8* %s, i64 %l, i32 1)
ret void
}

9
llvm/test/CodeGen/X86/memmove-1.ll Normal file
View File

@ -0,0 +1,9 @@
; RUN: llvm-as < %s | llc -march=x86 | grep {call memmove}
declare void @llvm.memmove.i64(i8* %d, i8* %s, i64 %l, i32 %a)
define void @foo(i8* %d, i8* %s, i64 %l)
{
call void @llvm.memmove.i64(i8* %d, i8* %s, i64 %l, i32 1)
ret void
}

9
llvm/test/CodeGen/X86/memmove-2.ll Normal file
View File

@ -0,0 +1,9 @@
; RUN: llvm-as < %s | llc -march=x86 | not grep call
declare void @llvm.memmove.i64(i8* %d, i8* %s, i64 %l, i32 %a)
define void @foo(i8* noalias %d, i8* noalias %s)
{
call void @llvm.memmove.i64(i8* %d, i8* %s, i64 32, i32 1)
ret void
}

9
llvm/test/CodeGen/X86/memmove-3.ll Normal file
View File

@ -0,0 +1,9 @@
; RUN: llvm-as < %s | llc -march=x86 | grep {call memmove}
declare void @llvm.memmove.i64(i8* %d, i8* %s, i64 %l, i32 %a)
define void @foo(i8* %d, i8* %s)
{
call void @llvm.memmove.i64(i8* %d, i8* %s, i64 32, i32 1)
ret void
}