Re: Sparse-LLVM issue compiling NULL pointers

From: Dibyendu Majumdar <mobile@majumdar.org.uk>
To: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
Cc: Linux-Sparse <linux-sparse@vger.kernel.org>
Subject: Re: Sparse-LLVM issue compiling NULL pointers
Date: Thu, 2 Mar 2017 18:41:35 +0000	[thread overview]
Message-ID: <CACXZuxf8-L6hy+TOd6pfmiAhoOXc-K5YJwUjonmmOGxv_djVnA@mail.gmail.com> (raw)
In-Reply-To: <20170302160403.zz5efgh34jvjh5q5@macpro.local>

Hi Luc,

On 2 March 2017 at 16:04, Luc Van Oostenryck
<luc.vanoostenryck@gmail.com> wrote:
> However, while running sparse-llvm on some code sample I use to test
> the linearization, I see that most errors are type errors and are
> related to pointer arithmetic, exactly where LLVM's getelemptr is used.
> Most offending instructions are OP_ADD (but since I have tests for
> bitfields I see also errors for OP_AND, OP_OR & OP_LSR).
> I guess that if you test OP_ADD instruction with pointer on one side
> and integer on tne other side and issue an appropriate LLVMBuildGEP(),
> things will already be much better.
>

This seems spot on as by making change as below, the final assertion
failure went away. I have not yet checked the generated code but that
is next.

 case OP_ADD:
  if (symbol_is_fp_type(C, insn->type))
   target = LLVMBuildFAdd(fn->builder, lhs, rhs, target_name);
  else {
   if (LLVMGetTypeKind(LLVMTypeOf(lhs)) == LLVMPointerTypeKind) {
    target = LLVMBuildGEP(fn->builder, lhs, &rhs, 1, "");
   }
   else if (LLVMGetTypeKind(LLVMTypeOf(lhs)) == LLVMPointerTypeKind) {
    target = LLVMBuildGEP(fn->builder, rhs, &lhs, 1, "");
   }
   else {
    target = LLVMBuildAdd(fn->builder, lhs, rhs, target_name);
   }
  }
  break;

Thanks and Regards