Re-commit r347417 "Re-Reinstate 347294 with a fix for the failures."

This was reverted in r347656 due to me thinking it caused a miscompile of
Chromium. Turns out it was the Chromium code that was broken.

1 files changed, 41 insertions, 13 deletions

diff --git a/clang/lib/CodeGen/CGBuiltin.cpp b/clang/lib/CodeGen/CGBuiltin.cpp
index cf7c0b0c288..cb15f19224e 100644
--- a/clang/lib/CodeGen/CGBuiltin.cpp
+++ b/clang/lib/CodeGen/CGBuiltin.cpp
@@ -1896,6 +1896,26 @@ RValue CodeGenFunction::EmitBuiltinExpr(const GlobalDecl GD, unsigned BuiltinID,
   case Builtin::BI_rotr64:
     return emitRotate(E, true);
 
+  case Builtin::BI__builtin_constant_p: {
+    llvm::Type *ResultType = ConvertType(E->getType());
+    if (CGM.getCodeGenOpts().OptimizationLevel == 0)
+      // At -O0, we don't perform inlining, so we don't need to delay the
+      // processing.
+      return RValue::get(ConstantInt::get(ResultType, 0));
+
+    const Expr *Arg = E->getArg(0);
+    QualType ArgType = Arg->getType();
+    if (!hasScalarEvaluationKind(ArgType) || ArgType->isFunctionType())
+      // We can only reason about scalar types.
+      return RValue::get(ConstantInt::get(ResultType, 0));
+
+    Value *ArgValue = EmitScalarExpr(Arg);
+    Value *F = CGM.getIntrinsic(Intrinsic::is_constant, ConvertType(ArgType));
+    Value *Result = Builder.CreateCall(F, ArgValue);
+    if (Result->getType() != ResultType)
+      Result = Builder.CreateIntCast(Result, ResultType, /*isSigned*/false);
+    return RValue::get(Result);
+  }
   case Builtin::BI__builtin_object_size: {
     unsigned Type =
         E->getArg(1)->EvaluateKnownConstInt(getContext()).getZExtValue();
@@ -2160,10 +2180,12 @@ RValue CodeGenFunction::EmitBuiltinExpr(const GlobalDecl GD, unsigned BuiltinID,
 
   case Builtin::BI__builtin___memcpy_chk: {
     // fold __builtin_memcpy_chk(x, y, cst1, cst2) to memcpy iff cst1<=cst2.
-    llvm::APSInt Size, DstSize;
-    if (!E->getArg(2)->EvaluateAsInt(Size, CGM.getContext()) ||
-        !E->getArg(3)->EvaluateAsInt(DstSize, CGM.getContext()))
+    Expr::EvalResult SizeResult, DstSizeResult;
+    if (!E->getArg(2)->EvaluateAsInt(SizeResult, CGM.getContext()) ||
+        !E->getArg(3)->EvaluateAsInt(DstSizeResult, CGM.getContext()))
       break;
+    llvm::APSInt Size = SizeResult.Val.getInt();
+    llvm::APSInt DstSize = DstSizeResult.Val.getInt();
     if (Size.ugt(DstSize))
       break;
     Address Dest = EmitPointerWithAlignment(E->getArg(0));
@@ -2184,10 +2206,12 @@ RValue CodeGenFunction::EmitBuiltinExpr(const GlobalDecl GD, unsigned BuiltinID,
 
   case Builtin::BI__builtin___memmove_chk: {
     // fold __builtin_memmove_chk(x, y, cst1, cst2) to memmove iff cst1<=cst2.
-    llvm::APSInt Size, DstSize;
-    if (!E->getArg(2)->EvaluateAsInt(Size, CGM.getContext()) ||
-        !E->getArg(3)->EvaluateAsInt(DstSize, CGM.getContext()))
+    Expr::EvalResult SizeResult, DstSizeResult;
+    if (!E->getArg(2)->EvaluateAsInt(SizeResult, CGM.getContext()) ||
+        !E->getArg(3)->EvaluateAsInt(DstSizeResult, CGM.getContext()))
       break;
+    llvm::APSInt Size = SizeResult.Val.getInt();
+    llvm::APSInt DstSize = DstSizeResult.Val.getInt();
     if (Size.ugt(DstSize))
       break;
     Address Dest = EmitPointerWithAlignment(E->getArg(0));
@@ -2222,10 +2246,12 @@ RValue CodeGenFunction::EmitBuiltinExpr(const GlobalDecl GD, unsigned BuiltinID,
   }
   case Builtin::BI__builtin___memset_chk: {
     // fold __builtin_memset_chk(x, y, cst1, cst2) to memset iff cst1<=cst2.
-    llvm::APSInt Size, DstSize;
-    if (!E->getArg(2)->EvaluateAsInt(Size, CGM.getContext()) ||
-        !E->getArg(3)->EvaluateAsInt(DstSize, CGM.getContext()))
+    Expr::EvalResult SizeResult, DstSizeResult;
+    if (!E->getArg(2)->EvaluateAsInt(SizeResult, CGM.getContext()) ||
+        !E->getArg(3)->EvaluateAsInt(DstSizeResult, CGM.getContext()))
       break;
+    llvm::APSInt Size = SizeResult.Val.getInt();
+    llvm::APSInt DstSize = DstSizeResult.Val.getInt();
     if (Size.ugt(DstSize))
       break;
     Address Dest = EmitPointerWithAlignment(E->getArg(0));
@@ -5739,10 +5765,11 @@ Value *CodeGenFunction::EmitARMBuiltinExpr(unsigned BuiltinID,
     llvm::FunctionType *FTy =
         llvm::FunctionType::get(VoidTy, /*Variadic=*/false);
 
-    APSInt Value;
-    if (!E->getArg(0)->EvaluateAsInt(Value, CGM.getContext()))
+    Expr::EvalResult Result;
+    if (!E->getArg(0)->EvaluateAsInt(Result, CGM.getContext()))
       llvm_unreachable("Sema will ensure that the parameter is constant");
 
+    llvm::APSInt Value = Result.Val.getInt();
     uint64_t ZExtValue = Value.zextOrTrunc(IsThumb ? 16 : 32).getZExtValue();
 
     llvm::InlineAsm *Emit =
@@ -6845,10 +6872,11 @@ Value *CodeGenFunction::EmitAArch64BuiltinExpr(unsigned BuiltinID,
   }
 
   if (BuiltinID == AArch64::BI__getReg) {
-    APSInt Value;
-    if (!E->getArg(0)->EvaluateAsInt(Value, CGM.getContext()))
+    Expr::EvalResult Result;
+    if (!E->getArg(0)->EvaluateAsInt(Result, CGM.getContext()))
       llvm_unreachable("Sema will ensure that the parameter is constant");
 
+    llvm::APSInt Value = Result.Val.getInt();
     LLVMContext &Context = CGM.getLLVMContext();
     std::string Reg = Value == 31 ? "sp" : "x" + Value.toString(10);