LLVM程序分析日记之插桩BranchInst

1. splitblockandinsertifthenelse()

一个代码例子：StackOverflow

2. SplitBlockAndInsertIfThen()

或者仅仅想插桩if then的逻辑，就可以用SplitBlockAndInsertIfThen()，其使用相对简单些，一个例子如下：

Value* val_c = NULL;
IRBuilder<> IRB(InsertPoint);
Value* cmp = IRB.CreateICmpEQ(val_a, val_b);
BranchInst *BI = cast<BranchInst>(
      SplitBlockAndInsertIfThen(cmp, InsertPoint, false, CallWeights));
/* Instrument at new basic block */
IRBuilder<> ThenB(BI);
val_c = ThenB.CreateAdd(val_a, val_b);
val_c = IRB.CreateSub(val_a, val_b);

上述插桩后的代码实现下面的效果：

...
if (val_a == val_b) {
      val_c = val_a + val_b;
}
val_c = val_a - val_b;

3. The third parameter of SplitBlockAndInsertIfThen() and splitblockandinsertifthenelse()

详见 https://stackoverflow.com/questions/65308323/llvm-suitable-parameters-for-the-createbranchweights