[CodeGen][NEON] Emit constants for "immediate" intrinsic arguments.

On ARM/AArch64, we currently always use EmitScalarExpr for the immediate
builtin arguments, instead of directly emitting the constant. When the
overflow sanitizer is enabled, this generates overflow intrinsics
instead of constants, breaking assumptions in various places.

Instead, use the knowledge of "immediates" to directly emit a constant:
- teach the tablegen backend to emit the "immediate" modifiers
- use those modifiers in the NEON CodeGen, on ARM and AArch64.

Fixes PR23517.

Differential Revision: http://reviews.llvm.org/D10045

llvm-svn: 239002

1 files changed, 38 insertions, 3 deletions

diff --git a/clang/lib/CodeGen/CGBuiltin.cpp b/clang/lib/CodeGen/CGBuiltin.cpp
index 5a48df235a9..d86534d5f8d 100644
--- a/clang/lib/CodeGen/CGBuiltin.cpp
+++ b/clang/lib/CodeGen/CGBuiltin.cpp
@@ -3491,6 +3491,13 @@ Value *CodeGenFunction::EmitARMBuiltinExpr(unsigned BuiltinID,
     }
   }
 
+  // Find out if any arguments are required to be integer constant
+  // expressions.
+  unsigned ICEArguments = 0;
+  ASTContext::GetBuiltinTypeError Error;
+  getContext().GetBuiltinType(BuiltinID, Error, &ICEArguments);
+  assert(Error == ASTContext::GE_None && "Should not codegen an error");
+
   SmallVector<Value*, 4> Ops;
   llvm::Value *Align = nullptr;
   for (unsigned i = 0, e = E->getNumArgs() - 1; i != e; i++) {
@@ -3553,7 +3560,17 @@ Value *CodeGenFunction::EmitARMBuiltinExpr(unsigned BuiltinID,
         continue;
       }
     }
-    Ops.push_back(EmitScalarExpr(E->getArg(i)));
+
+    if ((ICEArguments & (1 << i)) == 0) {
+      Ops.push_back(EmitScalarExpr(E->getArg(i)));
+    } else {
+      // If this is required to be a constant, constant fold it so that we know
+      // that the generated intrinsic gets a ConstantInt.
+      llvm::APSInt Result;
+      bool IsConst = E->getArg(i)->isIntegerConstantExpr(Result, getContext());
+      assert(IsConst && "Constant arg isn't actually constant?"); (void)IsConst;
+      Ops.push_back(llvm::ConstantInt::get(getLLVMContext(), Result));
+    }
   }
 
   switch (BuiltinID) {
@@ -4222,9 +4239,27 @@ Value *CodeGenFunction::EmitAArch64BuiltinExpr(unsigned BuiltinID,
     return Builder.CreateCall(F, {Arg0, Arg1});
   }
 
+  // Find out if any arguments are required to be integer constant
+  // expressions.
+  unsigned ICEArguments = 0;
+  ASTContext::GetBuiltinTypeError Error;
+  getContext().GetBuiltinType(BuiltinID, Error, &ICEArguments);
+  assert(Error == ASTContext::GE_None && "Should not codegen an error");
+
   llvm::SmallVector<Value*, 4> Ops;
-  for (unsigned i = 0, e = E->getNumArgs() - 1; i != e; i++)
-    Ops.push_back(EmitScalarExpr(E->getArg(i)));
+  for (unsigned i = 0, e = E->getNumArgs() - 1; i != e; i++) {
+    if ((ICEArguments & (1 << i)) == 0) {
+      Ops.push_back(EmitScalarExpr(E->getArg(i)));
+    } else {
+      // If this is required to be a constant, constant fold it so that we know
+      // that the generated intrinsic gets a ConstantInt.
+      llvm::APSInt Result;
+      bool IsConst = E->getArg(i)->isIntegerConstantExpr(Result, getContext());
+      assert(IsConst && "Constant arg isn't actually constant?");
+      (void)IsConst;
+      Ops.push_back(llvm::ConstantInt::get(getLLVMContext(), Result));
+    }
+  }
 
   auto SISDMap = makeArrayRef(AArch64SISDIntrinsicMap);
   const NeonIntrinsicInfo *Builtin = findNeonIntrinsicInMap(