Explicit Dependence in LLVM IR

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1

Hi,

I have a question regarding addition of explicit dependencies between two things in LLVM IR. Suppose I have following code:

%a = alloca i32
…
store 10, i32* %a
call foo()

Is there any way of adding an explicit dependence between the call to foo and the store? Can I add some dependence to represent that this call might access the previous store and any pass should not optimize it away.

Thanks

–Kapil

2

kapil anand wrote:

Hi,

I have a question regarding addition of explicit dependencies between
two things in LLVM IR. Suppose I have following code:

%a = alloca i32
......
store 10, i32* %a
call foo()

Is there any way of adding an explicit dependence between the call to
foo and the store? Can I add some dependence to represent that this call
might access the previous store and any pass should not optimize it away.

No, the call can't access the store because %a hasn't been written any place that @foo could possibly read it. LLVM proves that %a is an address that has not escaped and optimizes accordingly. If you want that to change, you could pass %a to @foo or maybe write %a to a global variable.

Nick