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List:       cfe-commits
Subject:    RE: r243206 - [CodeGen] Don't UBSan-ize the argument to __builtin_frame_address
From:       "Pieb, Wolfgang" <Wolfgang_Pieb () playstation ! sony ! com>
Date:       2015-07-28 22:54:23
Message-ID: 9AF3D5FFA8DB124D9EA12ABC02DD90A68691050B () USCULXMSG01 ! am ! sony ! com
[Download RAW message or body]

Hi, would it be possible to put this fix into the 3.7 branch?

Thanks

> -----Original Message-----
> From: cfe-commits-bounces@cs.uiuc.edu [mailto:cfe-commits-
> bounces@cs.uiuc.edu] On Behalf Of David Majnemer
> Sent: Friday, July 24, 2015 10:57 PM
> To: cfe-commits@cs.uiuc.edu
> Subject: r243206 - [CodeGen] Don't UBSan-ize the argument to
> __builtin_frame_address
> 
> Author: majnemer
> Date: Sat Jul 25 00:57:24 2015
> New Revision: 243206
> 
> URL: http://llvm.org/viewvc/llvm-project?rev=243206&view=rev
> Log:
> [CodeGen] Don't UBSan-ize the argument to __builtin_frame_address
> 
> __builtin_frame_address requires its argument to be a constant
> expression which already implies that it cannot have undefined
> behavior.
> However, we used EmitScalarExpr to emit the argument causing UBSan to
> try to check for overflow.
> 
> Instead, use the constant expression emission system.
> 
> This fixes PR24256.
> 
> Modified:
>     cfe/trunk/lib/CodeGen/CGBuiltin.cpp
>     cfe/trunk/test/CodeGen/integer-overflow.c
> 
> Modified: cfe/trunk/lib/CodeGen/CGBuiltin.cpp
> URL: http://llvm.org/viewvc/llvm-
> project/cfe/trunk/lib/CodeGen/CGBuiltin.cpp?rev=243206&r1=243205&r2=243
> 206&view=diff
> =======================================================================
> =======
> --- cfe/trunk/lib/CodeGen/CGBuiltin.cpp (original)
> +++ cfe/trunk/lib/CodeGen/CGBuiltin.cpp Sat Jul 25 00:57:24 2015
> @@ -866,14 +866,14 @@ RValue CodeGenFunction::EmitBuiltinExpr(
>                                        llvm::ConstantInt::get(Int32Ty,
> Offset)));
>    }
>    case Builtin::BI__builtin_return_address: {
> -    Value *Depth = EmitScalarExpr(E->getArg(0));
> -    Depth = Builder.CreateIntCast(Depth, Int32Ty, false);
> +    Value *Depth =
> +        CGM.EmitConstantExpr(E->getArg(0), getContext().UnsignedIntTy,
> + this);
>      Value *F = CGM.getIntrinsic(Intrinsic::returnaddress);
>      return RValue::get(Builder.CreateCall(F, Depth));
>    }
>    case Builtin::BI__builtin_frame_address: {
> -    Value *Depth = EmitScalarExpr(E->getArg(0));
> -    Depth = Builder.CreateIntCast(Depth, Int32Ty, false);
> +    Value *Depth =
> +        CGM.EmitConstantExpr(E->getArg(0), getContext().UnsignedIntTy,
> + this);
>      Value *F = CGM.getIntrinsic(Intrinsic::frameaddress);
>      return RValue::get(Builder.CreateCall(F, Depth));
>    }
> 
> Modified: cfe/trunk/test/CodeGen/integer-overflow.c
> URL: http://llvm.org/viewvc/llvm-
> project/cfe/trunk/test/CodeGen/integer-
> overflow.c?rev=243206&r1=243205&r2=243206&view=diff
> =======================================================================
> =======
> --- cfe/trunk/test/CodeGen/integer-overflow.c (original)
> +++ cfe/trunk/test/CodeGen/integer-overflow.c Sat Jul 25 00:57:24 2015
> @@ -72,4 +72,11 @@ void test1() {
>    // TRAPV: add i8 {{.*}}, 1
>    // CATCH_UB: add i8 {{.*}}, 1
>    ++PR9350;
> +
> +  // PR24256: don't instrument __builtin_frame_address.
> +  __builtin_frame_address(0 + 0);
> +  // DEFAULT:  call i8* @llvm.frameaddress(i32 0)
> +  // WRAPV:    call i8* @llvm.frameaddress(i32 0)
> +  // TRAPV:    call i8* @llvm.frameaddress(i32 0)
> +  // CATCH_UB: call i8* @llvm.frameaddress(i32 0)
>  }
> 
> 
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