我正在尝试在基本块上编写一个简单的传递，代码如下：
struct SimplePass : BasicBlockPass, InstVisitor<SimplePass>
{
... some initialisation and some finalization code
virtual bool runOnBasicBlock(BasicBlock& B) {
std::cout << "---This is a block divider---" << B.size() << std::endl;
visit(B);
return false;
}
void visitInstruction(Instruction& I){
std::cout << "Visiting every single instruction:" << I.getOpcodeName(I.getOpcode()) << std::endl;
}
void visitBranchInst(BranchInst& I) {
if(I.isUnconditional()) {
std::cout << "Encountered an unconditional branch!" << std::endl;
}
}
}
非常奇怪的是，我得到了一些这样的输出：
...
---This is a block divider---5
Visiting every single instruction:call
Visiting every single instruction:load
Visiting every single instruction:add
Visiting every single instruction:store
Encountered an unconditional branch!
---This is a block divider---7
Visiting every single instruction:phi
Visiting every single instruction:load
Visiting every single instruction:sub
Visiting every single instruction:call
Visiting every single instruction:load
Visiting every single instruction:icmp
---This is a block divider---3
......
很容易看出上面两个块中实际的指令数应该是5条和7条，但是visitInstrucion函数有时不会访问一个基本块的最后一条指令，为什么会出现这种情况呢？这应该发生吗？