detect default in SwitchInst

Hello All,

I’m trying to find whether SwitchInst has a default statement. I’m able to iterate through the case values using case_begin and case_end. If I try to detect default using case_default which returns an iterator which points to the default case.

Code Example:

case_default()->getCaseIndex() or case_default()->getSuccessorIndex() returns the same values for both default and non-default switch C code.

Any suggestions to solve this problem?

Regards.

LLVM IR switch instructions always have a default: https://llvm.org/docs/LangRef.html#switch-instruction - that jumps over the body of the switch. (when lowering C code to LLVM IR the default would be put after the loop, and the breaks from any case statements would jump over that default block)

In my case, for a function having a default statement in switch i could see a BB with label as sw.default is created:
switch i32 %0, label %sw.default [

]
sw.default: br label %sw.epilog

For a non-default switch statement function:
switch i32 %1, label %sw.epilog [

]

Ah, LLVM IR isn’t really the place to determine how the source was written - the names of those LLVM values aren’t always preserved (generally in optimized builds of clang the names will not be generated) - that said, even some LLVM features rely on the names, so it’s not totally unusable. You can use “getName()” on the value to get these names and inspect them, etc.