reapply the patches reverted in r149470 that reenable ConstantDataArray,

but with a critical fix to the SelectionDAG code that optimizes copies
from strings into immediate stores: the previous code was stopping reading
string data at the first nul.  Address this by adding a new argument to
llvm::getConstantStringInfo, preserving the behavior before the patch.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@149800 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 25 insertions, 40 deletions

diff --git a/lib/CodeGen/AsmPrinter/AsmPrinter.cpp b/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
index 43af3423de..241f20097e 100644
--- a/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
+++ b/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
@@ -1684,31 +1684,18 @@ static void EmitGlobalConstantDataSequential(const ConstantDataSequential *CDS,
 
 static void EmitGlobalConstantArray(const ConstantArray *CA, unsigned AddrSpace,
                                     AsmPrinter &AP) {
-  if (AddrSpace != 0 || !CA->isString()) {
-    // Not a string.  Print the values in successive locations.
+  // See if we can aggregate some values.  Make sure it can be
+  // represented as a series of bytes of the constant value.
+  int Value = isRepeatedByteSequence(CA, AP.TM);
 
-    // See if we can aggregate some values.  Make sure it can be
-    // represented as a series of bytes of the constant value.
-    int Value = isRepeatedByteSequence(CA, AP.TM);
-
-    if (Value != -1) {
-      uint64_t Bytes = AP.TM.getTargetData()->getTypeAllocSize(CA->getType());
-      AP.OutStreamer.EmitFill(Bytes, Value, AddrSpace);
-    }
-    else {
-      for (unsigned i = 0, e = CA->getNumOperands(); i != e; ++i)
-        EmitGlobalConstantImpl(CA->getOperand(i), AddrSpace, AP);
-    }
-    return;
+  if (Value != -1) {
+    uint64_t Bytes = AP.TM.getTargetData()->getTypeAllocSize(CA->getType());
+    AP.OutStreamer.EmitFill(Bytes, Value, AddrSpace);
+  }
+  else {
+    for (unsigned i = 0, e = CA->getNumOperands(); i != e; ++i)
+      EmitGlobalConstantImpl(CA->getOperand(i), AddrSpace, AP);
   }
-
-  // Otherwise, it can be emitted as .ascii.
-  SmallVector<char, 128> TmpVec;
-  TmpVec.reserve(CA->getNumOperands());
-  for (unsigned i = 0, e = CA->getNumOperands(); i != e; ++i)
-    TmpVec.push_back(cast<ConstantInt>(CA->getOperand(i))->getZExtValue());
-
-  AP.OutStreamer.EmitBytes(StringRef(TmpVec.data(), TmpVec.size()), AddrSpace);
 }
 
 static void EmitGlobalConstantVector(const ConstantVector *CV,
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index 18de13dc0a..0f209789c1 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -3298,8 +3298,7 @@ static SDValue getMemsetValue(SDValue Value, EVT VT, SelectionDAG &DAG,
 /// used when a memcpy is turned into a memset when the source is a constant
 /// string ptr.
 static SDValue getMemsetStringVal(EVT VT, DebugLoc dl, SelectionDAG &DAG,
-                                  const TargetLowering &TLI,
-                                  std::string &Str, unsigned Offset) {
+                                  const TargetLowering &TLI, StringRef Str) {
   // Handle vector with all elements zero.
   if (Str.empty()) {
     if (VT.isInteger())
@@ -3317,15 +3316,18 @@ static SDValue getMemsetStringVal(EVT VT, DebugLoc dl, SelectionDAG &DAG,
   }
 
   assert(!VT.isVector() && "Can't handle vector type here!");
-  unsigned NumBits = VT.getSizeInBits();
-  unsigned MSB = NumBits / 8;
+  unsigned NumVTBytes = VT.getSizeInBits() / 8;
+  unsigned NumBytes = std::min(NumVTBytes, unsigned(Str.size()));
+
   uint64_t Val = 0;
-  if (TLI.isLittleEndian())
-    Offset = Offset + MSB - 1;
-  for (unsigned i = 0; i != MSB; ++i) {
-    Val = (Val << 8) | (unsigned char)Str[Offset];
-    Offset += TLI.isLittleEndian() ? -1 : 1;
+  if (TLI.isLittleEndian()) {
+    for (unsigned i = 0; i != NumBytes; ++i)
+      Val |= (uint64_t)(unsigned char)Str[i] << i*8;
+  } else {
+    for (unsigned i = 0; i != NumBytes; ++i)
+      Val |= (uint64_t)(unsigned char)Str[i] << (NumVTBytes-i-1)*8;
   }
+
   return DAG.getConstant(Val, VT);
 }
 
@@ -3340,7 +3342,7 @@ static SDValue getMemBasePlusOffset(SDValue Base, unsigned Offset,
 
 /// isMemSrcFromString - Returns true if memcpy source is a string constant.
 ///
-static bool isMemSrcFromString(SDValue Src, std::string &Str) {
+static bool isMemSrcFromString(SDValue Src, StringRef &Str) {
   unsigned SrcDelta = 0;
   GlobalAddressSDNode *G = NULL;
   if (Src.getOpcode() == ISD::GlobalAddress)
@@ -3354,11 +3356,7 @@ static bool isMemSrcFromString(SDValue Src, std::string &Str) {
   if (!G)
     return false;
 
-  const GlobalVariable *GV = dyn_cast<GlobalVariable>(G->getGlobal());
-  if (GV && GetConstantStringInfo(GV, Str, SrcDelta, false))
-    return true;
-
-  return false;
+  return getConstantStringInfo(G->getGlobal(), Str, SrcDelta, false);
 }
 
 /// FindOptimalMemOpLowering - Determines the optimial series memory ops
@@ -3461,7 +3459,7 @@ static SDValue getMemcpyLoadsAndStores(SelectionDAG &DAG, DebugLoc dl,
   unsigned SrcAlign = DAG.InferPtrAlignment(Src);
   if (Align > SrcAlign)
     SrcAlign = Align;
-  std::string Str;
+  StringRef Str;
   bool CopyFromStr = isMemSrcFromString(Src, Str);
   bool isZeroStr = CopyFromStr && Str.empty();
   unsigned Limit = AlwaysInline ? ~0U : TLI.getMaxStoresPerMemcpy(OptSize);
@@ -3498,7 +3496,7 @@ static SDValue getMemcpyLoadsAndStores(SelectionDAG &DAG, DebugLoc dl,
       // We only handle zero vectors here.
       // FIXME: Handle other cases where store of vector immediate is done in
       // a single instruction.
-      Value = getMemsetStringVal(VT, dl, DAG, TLI, Str, SrcOff);
+      Value = getMemsetStringVal(VT, dl, DAG, TLI, Str.substr(SrcOff));
       Store = DAG.getStore(Chain, dl, Value,
                            getMemBasePlusOffset(Dst, DstOff, DAG),
                            DstPtrInfo.getWithOffset(DstOff), isVol,