本笔记目的是自建一个 Pass 流水来实现想要的优化功能，可以直接参考 patch：
diff --git a/llvm/lib/Passes/PassBuilderPipelines.cpp b/llvm/lib/Passes/PassBuilderPipelines.cpp
index 546a5eb1ec28..e68b497a23ab 100644
--- a/llvm/lib/Passes/PassBuilderPipelines.cpp
+++ b/llvm/lib/Passes/PassBuilderPipelines.cpp
@@ -305,6 +305,11 @@ static cl::opt<std::string> InstrumentColdFuncOnlyPath(
"with --pgo-instrument-cold-function-only)"),
cl::Hidden);
+static cl::opt<bool> BuildCustomPipeline(
+ "custom-pipelin ...
