[llvm-dev] Wrong Users count for global string in clang/test/CodeGen/2009-02-13-zerosize-union-field.c

[Nimrod Partush via llvm-dev]

I see, thanks!

I actually was iterating over the users of the GEP in another place but my
mistake was altering the containing function while iterating, which ended
the iteration mid way.

Cheers,
--Nimrod.


On Fri, Nov 27, 2020 at 4:55 AM Craig Topper <craig.topper at gmail.com> wrote:

> Each call appears to use an identical ConstantExpr getelementptr. Each of
> those ConstantExprs is represented by the same object in the memory
> representation of IR even though its printed in 4 separate places. If you
> walk the users of that object you should find the 4 calls.
>
> ~Craig
>
>
> On Thu, Nov 26, 2020 at 5:26 PM Nimrod Partush via llvm-dev <
> llvm-dev at lists.llvm.org> wrote:
>
>> Hi,
>>
>> I'm writing some code transformations using CLang. When I run my code on clang/test/CodeGen/2009-02-13-zerosize-union-field.c
>> :
>>
>> typedef unsigned int Foo __attribute__((aligned(32)));
>> typedef union{Foo:0;}a;
>> typedef union{int x; Foo:0;}b;
>> extern int printf(const char*, ...);
>> int main() {
>>   // CHECK: getelementptr inbounds ([5 x i8], [5 x i8]* @.str, i32 0, i32
>> 0), i32 0
>>   printf("%ld\n", sizeof(a));
>>   // CHECK: getelementptr inbounds ([5 x i8], [5 x i8]* @.str, i32 0, i32
>> 0), i32 1
>>   printf("%ld\n", __alignof__(a));
>>   // CHECK: getelementptr inbounds ([5 x i8], [5 x i8]* @.str, i32 0, i32
>> 0), i32 4
>>   printf("%ld\n", sizeof(b));
>>   // CHECK: getelementptr inbounds ([5 x i8], [5 x i8]* @.str, i32 0, i32
>> 0), i32 4
>>   printf("%ld\n", __alignof__(b));
>> }
>>
>> I see that when I iterate the users() of the "%ld\n" string, only the
>> last user is reported. Here's my code for doing the iteration:
>>
>> for (llvm::GlobalVariable &Glob : TheModule.globals())
>>   for (User *U : Glob.users())
>>     outs() << "User " << *U << "\n";
>>
>> The 4 different calls are clearly visible in the .ll file:
>>
>>   %call = call i32 (i8*, ...) @printf(i8* getelementptr inbounds ([5 x
>> i8], [5 x i8]* @"??_C at _04PEDNGLFL@?$CFld?6?$AA@", i64 0, i64 0), i64 4)
>>   %call1 = call i32 (i8*, ...) @printf(i8* getelementptr inbounds ([5 x
>> i8], [5 x i8]* @"??_C at _04PEDNGLFL@?$CFld?6?$AA@", i64 0, i64 0), i64 1)
>>   %call2 = call i32 (i8*, ...) @printf(i8* getelementptr inbounds ([5 x
>> i8], [5 x i8]* @"??_C at _04PEDNGLFL@?$CFld?6?$AA@", i64 0, i64 0), i64 4)
>>   %call3 = call i32 (i8*, ...) @printf(i8* getelementptr inbounds ([5 x
>> i8], [5 x i8]* @"??_C at _04PEDNGLFL@?$CFld?6?$AA@", i64 0, i64 0), i64 4)
>>
>> Any idea why this is happening?
>>
>> Thanks
>>
>> --Nimrod.
>> _______________________________________________
>> LLVM Developers mailing list
>> llvm-dev at lists.llvm.org
>> https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>>
>
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