3 files changed, 66 insertions, 26 deletions

diff --git a/llvm/lib/IR/Attributes.cpp b/llvm/lib/IR/Attributes.cpp
index 0f2b7a0ebb4..9d9d948527c 100644
--- a/llvm/lib/IR/Attributes.cpp
+++ b/llvm/lib/IR/Attributes.cpp
@@ -166,6 +166,8 @@ std::string Attribute::getAsString(bool InAttrGrp) const {
     return "builtin";
   if (hasAttribute(Attribute::ByVal))
     return "byval";
+  if (hasAttribute(Attribute::InAlloca))
+    return "inalloca";
   if (hasAttribute(Attribute::InlineHint))
     return "inlinehint";
   if (hasAttribute(Attribute::InReg))
@@ -388,6 +390,7 @@ uint64_t AttributeImpl::getAttrMask(Attribute::AttrKind Val) {
   case Attribute::Cold:            return 1ULL << 40;
   case Attribute::Builtin:         return 1ULL << 41;
   case Attribute::OptimizeNone:    return 1ULL << 42;
+  case Attribute::InAlloca:        return 1ULL << 43;
   }
   llvm_unreachable("Unsupported attribute type");
 }
@@ -1174,7 +1177,8 @@ AttributeSet AttributeFuncs::typeIncompatible(Type *Ty, uint64_t Index) {
       .addAttribute(Attribute::NoCapture)
       .addAttribute(Attribute::ReadNone)
       .addAttribute(Attribute::ReadOnly)
-      .addAttribute(Attribute::StructRet);
+      .addAttribute(Attribute::StructRet)
+      .addAttribute(Attribute::InAlloca);
 
   return AttributeSet::get(Ty->getContext(), Index, Incompatible);
 }
diff --git a/llvm/lib/IR/Function.cpp b/llvm/lib/IR/Function.cpp
index e8a2402b3d9..970bbaeed8b 100644
--- a/llvm/lib/IR/Function.cpp
+++ b/llvm/lib/IR/Function.cpp
@@ -84,6 +84,14 @@ bool Argument::hasByValAttr() const {
     hasAttribute(getArgNo()+1, Attribute::ByVal);
 }
 
+/// \brief Return true if this argument has the inalloca attribute on it in
+/// its containing function.
+bool Argument::hasInAllocaAttr() const {
+  if (!getType()->isPointerTy()) return false;
+  return getParent()->getAttributes().
+    hasAttribute(getArgNo()+1, Attribute::InAlloca);
+}
+
 unsigned Argument::getParamAlignment() const {
   assert(getType()->isPointerTy() && "Only pointers have alignments");
   return getParent()->getParamAlignment(getArgNo()+1);
diff --git a/llvm/lib/IR/Verifier.cpp b/llvm/lib/IR/Verifier.cpp
index febd29f0725..35b786ecf27 100644
--- a/llvm/lib/IR/Verifier.cpp
+++ b/llvm/lib/IR/Verifier.cpp
@@ -813,26 +813,25 @@ void Verifier::VerifyParameterAttrs(AttributeSet Attrs, unsigned Idx, Type *Ty,
             !Attrs.hasAttribute(Idx, Attribute::Nest) &&
             !Attrs.hasAttribute(Idx, Attribute::StructRet) &&
             !Attrs.hasAttribute(Idx, Attribute::NoCapture) &&
-            !Attrs.hasAttribute(Idx, Attribute::Returned),
-            "Attribute 'byval', 'nest', 'sret', 'nocapture', and 'returned' "
-            "do not apply to return values!", V);
-
-  // Check for mutually incompatible attributes.
-  Assert1(!((Attrs.hasAttribute(Idx, Attribute::ByVal) &&
-             Attrs.hasAttribute(Idx, Attribute::Nest)) ||
-            (Attrs.hasAttribute(Idx, Attribute::ByVal) &&
-             Attrs.hasAttribute(Idx, Attribute::StructRet)) ||
-            (Attrs.hasAttribute(Idx, Attribute::Nest) &&
-             Attrs.hasAttribute(Idx, Attribute::StructRet))), "Attributes "
-          "'byval, nest, and sret' are incompatible!", V);
-
-  Assert1(!((Attrs.hasAttribute(Idx, Attribute::ByVal) &&
-             Attrs.hasAttribute(Idx, Attribute::Nest)) ||
-            (Attrs.hasAttribute(Idx, Attribute::ByVal) &&
-             Attrs.hasAttribute(Idx, Attribute::InReg)) ||
-            (Attrs.hasAttribute(Idx, Attribute::Nest) &&
-             Attrs.hasAttribute(Idx, Attribute::InReg))), "Attributes "
-          "'byval, nest, and inreg' are incompatible!", V);
+            !Attrs.hasAttribute(Idx, Attribute::Returned) &&
+            !Attrs.hasAttribute(Idx, Attribute::InAlloca),
+            "Attributes 'byval', 'inalloca', 'nest', 'sret', 'nocapture', and "
+            "'returned' do not apply to return values!", V);
+
+  // Check for mutually incompatible attributes.  Only inreg is compatible with
+  // sret.
+  unsigned AttrCount = 0;
+  AttrCount += Attrs.hasAttribute(Idx, Attribute::ByVal);
+  AttrCount += Attrs.hasAttribute(Idx, Attribute::InAlloca);
+  AttrCount += Attrs.hasAttribute(Idx, Attribute::StructRet) ||
+               Attrs.hasAttribute(Idx, Attribute::InReg);
+  AttrCount += Attrs.hasAttribute(Idx, Attribute::Nest);
+  Assert1(AttrCount <= 1, "Attributes 'byval', 'inalloca', 'inreg', 'nest', "
+                          "and 'sret' are incompatible!", V);
+
+  Assert1(!(Attrs.hasAttribute(Idx, Attribute::InAlloca) &&
+            Attrs.hasAttribute(Idx, Attribute::ReadOnly)), "Attributes "
+          "'inalloca and readonly' are incompatible!", V);
 
   Assert1(!(Attrs.hasAttribute(Idx, Attribute::StructRet) &&
             Attrs.hasAttribute(Idx, Attribute::Returned)), "Attributes "
@@ -855,14 +854,18 @@ void Verifier::VerifyParameterAttrs(AttributeSet Attrs, unsigned Idx, Type *Ty,
           "Wrong types for attribute: " +
           AttributeFuncs::typeIncompatible(Ty, Idx).getAsString(Idx), V);
 
-  if (PointerType *PTy = dyn_cast<PointerType>(Ty))
-    Assert1(!Attrs.hasAttribute(Idx, Attribute::ByVal) ||
-            PTy->getElementType()->isSized(),
-            "Attribute 'byval' does not support unsized types!", V);
-  else
+  if (PointerType *PTy = dyn_cast<PointerType>(Ty)) {
+    if (!PTy->getElementType()->isSized()) {
+      Assert1(!Attrs.hasAttribute(Idx, Attribute::ByVal) &&
+              !Attrs.hasAttribute(Idx, Attribute::InAlloca),
+              "Attributes 'byval' and 'inalloca' do not support unsized types!",
+              V);
+    }
+  } else {
     Assert1(!Attrs.hasAttribute(Idx, Attribute::ByVal),
             "Attribute 'byval' only applies to parameters with pointer type!",
             V);
+  }
 }
 
 // VerifyFunctionAttrs - Check parameter attributes against a function type.
@@ -1533,6 +1536,15 @@ void Verifier::VerifyCallSite(CallSite CS) {
   // Verify call attributes.
   VerifyFunctionAttrs(FTy, Attrs, I);
 
+  // Verify that values used for inalloca parameters are in fact allocas.
+  for (unsigned i = 0, e = CS.arg_size(); i != e; ++i) {
+    if (!Attrs.hasAttribute(1 + i, Attribute::InAlloca))
+      continue;
+    Value *Arg = CS.getArgument(i);
+    Assert2(isa<AllocaInst>(Arg), "Inalloca argument is not an alloca!", I,
+            Arg);
+  }
+
   if (FTy->isVarArg()) {
     // FIXME? is 'nest' even legal here?
     bool SawNest = false;
@@ -1870,6 +1882,22 @@ void Verifier::visitAllocaInst(AllocaInst &AI) {
           &AI);
   Assert1(AI.getArraySize()->getType()->isIntegerTy(),
           "Alloca array size must have integer type", &AI);
+
+  // Verify that an alloca instruction is not used with inalloca more than once.
+  unsigned InAllocaUses = 0;
+  for (User::use_iterator UI = AI.use_begin(), UE = AI.use_end(); UI != UE;
+       ++UI) {
+    CallSite CS(*UI);
+    if (!CS)
+      continue;
+    unsigned ArgNo = CS.getArgumentNo(UI);
+    if (CS.isInAllocaArgument(ArgNo)) {
+      InAllocaUses++;
+      Assert1(InAllocaUses <= 1,
+              "Allocas can be used at most once with inalloca!", &AI);
+    }
+  }
+
   visitInstruction(AI);
 }