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.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@41489 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
index 12024ff..92e34bb 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
@@ -409,6 +409,7 @@
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 @@
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 @@
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 @@
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 @@
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::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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
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;