4 files changed, 56 insertions, 0 deletions
diff --git a/clang/lib/CodeGen/CGBuiltin.cpp b/clang/lib/CodeGen/CGBuiltin.cpp
index c73a6e1b061..54566aa7e51 100644
--- a/clang/lib/CodeGen/CGBuiltin.cpp
+++ b/clang/lib/CodeGen/CGBuiltin.cpp
@@ -1147,6 +1147,19 @@ RValue CodeGenFunction::EmitBuiltinExpr(const FunctionDecl *FD,
     AI->setAlignment(SuitableAlignmentInBytes);
     return RValue::get(AI);
   }
+
+  case Builtin::BI__builtin_alloca_with_align: {
+    Value *Size = EmitScalarExpr(E->getArg(0));
+    Value *AlignmentValue = EmitScalarExpr(E->getArg(1));
+    auto *AlignmentCI = cast<ConstantInt>(AlignmentValue);
+    unsigned Alignment = AlignmentCI->getZExtValue();
+    const TargetInfo &TI = getContext().getTargetInfo();
+    unsigned AlignmentInBytes = Alignment / TI.getCharWidth();
+    AllocaInst *AI = Builder.CreateAlloca(Builder.getInt8Ty(), Size);
+    AI->setAlignment(AlignmentInBytes);
+    return RValue::get(AI);
+  }
+
   case Builtin::BIbzero:
   case Builtin::BI__builtin_bzero: {
     Address Dest = EmitPointerWithAlignment(E->getArg(0));
diff --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp
index c73bd4c6ed2..a4e3c5b8b24 100644
--- a/clang/lib/Sema/SemaChecking.cpp
+++ b/clang/lib/Sema/SemaChecking.cpp
@@ -791,6 +791,10 @@ Sema::CheckBuiltinFunctionCall(FunctionDecl *FDecl, unsigned BuiltinID,
     if (SemaBuiltinPrefetch(TheCall))
       return ExprError();
     break;
+  case Builtin::BI__builtin_alloca_with_align:
+    if (SemaBuiltinAllocaWithAlign(TheCall))
+      return ExprError();
+    break;
   case Builtin::BI__assume:
   case Builtin::BI__builtin_assume:
     if (SemaBuiltinAssume(TheCall))
@@ -3904,6 +3908,36 @@ bool Sema::SemaBuiltinAssume(CallExpr *TheCall) {
 }
 
 /// Handle __builtin_assume_aligned. This is declared
+/// as (size_t, size_t) where the second size_t must be a power of 2 greater
+/// than 8.
+bool Sema::SemaBuiltinAllocaWithAlign(CallExpr *TheCall) {
+  // The alignment must be a constant integer.
+  Expr *Arg = TheCall->getArg(1);
+
+  // We can't check the value of a dependent argument.
+  if (!Arg->isTypeDependent() && !Arg->isValueDependent()) {
+    llvm::APSInt Result = Arg->EvaluateKnownConstInt(Context);
+
+    if (!Result.isPowerOf2())
+      return Diag(TheCall->getLocStart(),
+                  diag::err_alignment_not_power_of_two)
+           << Arg->getSourceRange();
+
+    if (Result < Context.getCharWidth())
+      return Diag(TheCall->getLocStart(), diag::err_alignment_too_small)
+           << (unsigned)Context.getCharWidth()
+           << Arg->getSourceRange();
+
+    if (Result > INT32_MAX)
+      return Diag(TheCall->getLocStart(), diag::err_alignment_too_big)
+           << INT32_MAX
+           << Arg->getSourceRange();
+  }
+
+  return false;
+}
+
+/// Handle __builtin_assume_aligned. This is declared
 /// as (const void*, size_t, ...) and can take one optional constant int arg.
 bool Sema::SemaBuiltinAssumeAligned(CallExpr *TheCall) {
   unsigned NumArgs = TheCall->getNumArgs();
diff --git a/clang/lib/StaticAnalyzer/Checkers/BuiltinFunctionChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/BuiltinFunctionChecker.cpp
index dab2f61229a..8c2aef21b3c 100644
--- a/clang/lib/StaticAnalyzer/Checkers/BuiltinFunctionChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/BuiltinFunctionChecker.cpp
@@ -55,6 +55,7 @@ bool BuiltinFunctionChecker::evalCall(const CallExpr *CE,
     return true;
   }
 
+  case Builtin::BI__builtin_alloca_with_align:
   case Builtin::BI__builtin_alloca: {
     // FIXME: Refactor into StoreManager itself?
     MemRegionManager& RM = C.getStoreManager().getRegionManager();
diff --git a/clang/lib/StaticAnalyzer/Checkers/UnixAPIChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/UnixAPIChecker.cpp
index 4b78c205834..c9dafb518c4 100644
--- a/clang/lib/StaticAnalyzer/Checkers/UnixAPIChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/UnixAPIChecker.cpp
@@ -43,6 +43,7 @@ public:
   void CheckReallocZero(CheckerContext &C, const CallExpr *CE) const;
   void CheckReallocfZero(CheckerContext &C, const CallExpr *CE) const;
   void CheckAllocaZero(CheckerContext &C, const CallExpr *CE) const;
+  void CheckAllocaWithAlignZero(CheckerContext &C, const CallExpr *CE) const;
   void CheckVallocZero(CheckerContext &C, const CallExpr *CE) const;
 
   typedef void (UnixAPIChecker::*SubChecker)(CheckerContext &,
@@ -337,6 +338,11 @@ void UnixAPIChecker::CheckAllocaZero(CheckerContext &C,
   BasicAllocationCheck(C, CE, 1, 0, "alloca");
 }
 
+void UnixAPIChecker::CheckAllocaWithAlignZero(CheckerContext &C,
+                                              const CallExpr *CE) const {
+  BasicAllocationCheck(C, CE, 2, 0, "__builtin_alloca_with_align");
+}
+
 void UnixAPIChecker::CheckVallocZero(CheckerContext &C,
                                      const CallExpr *CE) const {
   BasicAllocationCheck(C, CE, 1, 0, "valloc");
@@ -366,6 +372,8 @@ void UnixAPIChecker::checkPreStmt(const CallExpr *CE,
       .Case("realloc", &UnixAPIChecker::CheckReallocZero)
       .Case("reallocf", &UnixAPIChecker::CheckReallocfZero)
       .Cases("alloca", "__builtin_alloca", &UnixAPIChecker::CheckAllocaZero)
+      .Case("__builtin_alloca_with_align",
+            &UnixAPIChecker::CheckAllocaWithAlignZero)
       .Case("valloc", &UnixAPIChecker::CheckVallocZero)
       .Default(nullptr);