commit 98d1ec1e99625176626b0bcd44cef7df6e89b289
author Michael Gottesman <mgottesman@apple.com> Thu Jun 20 23:28:10 2013 +0000
committer Michael Gottesman <mgottesman@apple.com> Thu Jun 20 23:28:10 2013 +0000
tree 5e61718a1e26207b40c76af2ac52f476d738874c
parent a4993778f65212f01168c857cf3043e99ba85c9f

[checked-arithmetic builtins] Added builtins to enable users to perform checked-arithmetic in c.

This will enable users in security critical applications to perform
checked-arithmetic in a fast safe manner that is amenable to c.

Tests/an update to Language Extensions is included as well.

rdar://13421498.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@184497 91177308-0d34-0410-b5e6-96231b3b80d8

lib/CodeGen/CGBuiltin.cpp

diff --git a/lib/CodeGen/CGBuiltin.cpp b/lib/CodeGen/CGBuiltin.cpp
index 90b8ebc..c57c767 100644
--- a/lib/CodeGen/CGBuiltin.cpp
+++ b/lib/CodeGen/CGBuiltin.cpp
@@ -1414,6 +1414,77 @@
     CarryOutStore->setAlignment(CarryOutPtr.second);
     return RValue::get(Sum2);
   }
+  case Builtin::BI__builtin_uadd_overflow:
+  case Builtin::BI__builtin_uaddl_overflow:
+  case Builtin::BI__builtin_uaddll_overflow:
+  case Builtin::BI__builtin_usub_overflow:
+  case Builtin::BI__builtin_usubl_overflow:
+  case Builtin::BI__builtin_usubll_overflow:
+  case Builtin::BI__builtin_umul_overflow:
+  case Builtin::BI__builtin_umull_overflow:
+  case Builtin::BI__builtin_umulll_overflow:
+  case Builtin::BI__builtin_sadd_overflow:
+  case Builtin::BI__builtin_saddl_overflow:
+  case Builtin::BI__builtin_saddll_overflow:
+  case Builtin::BI__builtin_ssub_overflow:
+  case Builtin::BI__builtin_ssubl_overflow:
+  case Builtin::BI__builtin_ssubll_overflow:
+  case Builtin::BI__builtin_smul_overflow:
+  case Builtin::BI__builtin_smull_overflow:
+  case Builtin::BI__builtin_smulll_overflow: {
+
+    // We translate all of these builtins directly to the relevant llvm IR node.
+
+    // Scalarize our inputs.
+    llvm::Value *X = EmitScalarExpr(E->getArg(0));
+    llvm::Value *Y = EmitScalarExpr(E->getArg(1));
+    std::pair<llvm::Value *, unsigned> SumOutPtr =
+      EmitPointerWithAlignment(E->getArg(2));
+
+    // Decide which of the overflow intrinsics we are lowering to:
+    llvm::Intrinsic::ID IntrinsicId;
+    switch (BuiltinID) {
+    default: llvm_unreachable("Unknown security overflow builtin id.");
+    case Builtin::BI__builtin_uadd_overflow:
+    case Builtin::BI__builtin_uaddl_overflow:
+    case Builtin::BI__builtin_uaddll_overflow:
+      IntrinsicId = llvm::Intrinsic::uadd_with_overflow;
+      break;
+    case Builtin::BI__builtin_usub_overflow:
+    case Builtin::BI__builtin_usubl_overflow:
+    case Builtin::BI__builtin_usubll_overflow:
+      IntrinsicId = llvm::Intrinsic::usub_with_overflow;
+      break;
+    case Builtin::BI__builtin_umul_overflow:
+    case Builtin::BI__builtin_umull_overflow:
+    case Builtin::BI__builtin_umulll_overflow:
+      IntrinsicId = llvm::Intrinsic::umul_with_overflow;
+      break;
+    case Builtin::BI__builtin_sadd_overflow:
+    case Builtin::BI__builtin_saddl_overflow:
+    case Builtin::BI__builtin_saddll_overflow:
+      IntrinsicId = llvm::Intrinsic::sadd_with_overflow;
+      break;
+    case Builtin::BI__builtin_ssub_overflow:
+    case Builtin::BI__builtin_ssubl_overflow:
+    case Builtin::BI__builtin_ssubll_overflow:
+      IntrinsicId = llvm::Intrinsic::ssub_with_overflow;
+      break;
+    case Builtin::BI__builtin_smul_overflow:
+    case Builtin::BI__builtin_smull_overflow:
+    case Builtin::BI__builtin_smulll_overflow:
+      IntrinsicId = llvm::Intrinsic::smul_with_overflow;
+      break;
+    }
+
+    
+    llvm::Value *Carry;
+    llvm::Value *Sum = EmitOverflowIntrinsic(*this, IntrinsicId, X, Y, Carry);
+    llvm::StoreInst *SumOutStore = Builder.CreateStore(Sum, SumOutPtr.first);
+    SumOutStore->setAlignment(SumOutPtr.second);
+
+    return RValue::get(Carry);
+  }
   case Builtin::BI__noop:
     return RValue::get(0);
   }