From mboxrd@z Thu Jan  1 00:00:00 1970
From: Dibyendu Majumdar <mobile@majumdar.org.uk>
Subject: Re: sparse-llvm incorrect type when ealing with union type
Date: Sun, 19 Mar 2017 20:48:03 +0000
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To: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
Cc: Linux-Sparse <linux-sparse@vger.kernel.org>

Hi Luc,

On 19 March 2017 at 17:55, Dibyendu Majumdar <mobile@majumdar.org.uk> wrote:
> On 19 March 2017 at 17:15, Luc Van Oostenryck
> <luc.vanoostenryck@gmail.com> wrote:
>> On Sun, Mar 19, 2017 at 5:37 PM, Dibyendu Majumdar
>> <mobile@majumdar.org.uk> wrote:
>>> On 19 March 2017 at 15:36, Luc Van Oostenryck
>>> <luc.vanoostenryck@gmail.com> wrote:
>>>>
>>> I noticed that in the latest patch series for add/sub you are not
>>> using GEP anymore, and there is a conversion to target type at the end
>>> of a binary op. I will try out these changes and report back.
>>
>> Yes. It's not that the GEP was wrong but it was not enough and the more
>> complete solution made this one unneeded.
>>
>
> I have now tested the changes to binary op implementation - and I can
> confirm that all my tests pass, and this appears to be a better
> approach than the previous one that used the GEP instruction.
>

It seems that we can replace the other GEP too with pointer
arithmetic. This makes LLVM output closer to the IR generated by
sparse.

The change required is in calc_memop_addr():

 /* int type large enough to hold a pointer */
 int_type = LLVMIntType(bits_in_pointer);
 /* IMPORTANT offset can be negative */
 off = LLVMConstInt(int_type, (int) insn->offset, 0);
 /* convert src to the effective pointer type */
 src = pseudo_to_value(fn, insn, insn->src);
 as = LLVMGetPointerAddressSpace(LLVMTypeOf(src));
 addr_type = LLVMPointerType(insn_symbol_type(insn), as);
 src = value_to_ivalue(fn, src);
 addr = LLVMBuildAdd(fn->builder, src, off, "");
 addr = LLVMBuildIntToPtr(fn->builder, addr, addr_type, "");
 return addr;


Regards
Dibyendu