LLVM - Invalid instruction with no BB

Someone know what this error means? I get the error when I try to disassemble a file written by LLVMWriteBitcodeToFile. When I dump the module using LLVMDumpModule and manually ass开发者_开发百科emble and disassemble the file no error occurs. The module that i am trying to compile (from LLVMDumpModule) looks like:

; ModuleID = 'Test'

define i32 @a(i32) {
entry:
  %icmp = icmp eq i32 %0, 1                       ; <i1> [#uses=1]
  br i1 %icmp, label %_L2, label %_L3

_L1:                                              ; preds = %_L3
  ret i32 %0
  call void @RAISE(i32 1)
  unreachable

_L2:                                              ; preds = %entry
  ret i32 1

_L3:                                              ; preds = %entry
  br label %_L1
}

declare void @RAISE(i32)

Any clues?

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I don't know the error message is displayed for which instruction, but my guess is the

call void @RAISE(i32 1), 

and the reason might be that it is after a terminator instruction (the last instruction in a basic block)

ret i32 %0

, and hence no parent BB

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I've run into similar symptoms before, as a result of incorrectly constructing the in-memory LLVM objects representing the IR. Play around with the code that originally generated this, and make sure it's not doing anything fishy.