[NFC][Coroutines] Remove redundant checks for replacing PrepareFns

[yuxuanchen1997]

If Coroutines.empty() the following loop is going to be skipped entirely and same goes for PrepareFns.empty(). These two conditions here aren't useful and adds to complexity.

[llvmbot]

@llvm/pr-subscribers-llvm-transforms

@llvm/pr-subscribers-coroutines

Author: Yuxuan Chen (yuxuanchen1997)

Changes

If Coroutines.empty() the following loop is going to be skipped entirely and same goes for PrepareFns.empty(). These two conditions here aren't useful and adds to complexity.

---

Full diff: https://github.com/llvm/llvm-project/pull/98392.diff

1 Files Affected:

• (modified) llvm/lib/Transforms/Coroutines/CoroSplit.cpp (-8)

diff --git a/llvm/lib/Transforms/Coroutines/CoroSplit.cpp b/llvm/lib/Transforms/Coroutines/CoroSplit.cpp
index 299b514d34f1c..0b52d1e4490cb 100644
--- a/llvm/lib/Transforms/Coroutines/CoroSplit.cpp
+++ b/llvm/lib/Transforms/Coroutines/CoroSplit.cpp
@@ -2108,12 +2108,6 @@ PreservedAnalyses CoroSplitPass::run(LazyCallGraph::SCC &C,
   if (Coroutines.empty() && PrepareFns.empty())
     return PreservedAnalyses::all();
 
-  if (Coroutines.empty()) {
-    for (auto *PrepareFn : PrepareFns) {
-      replaceAllPrepares(PrepareFn, CG, C);
-    }
-  }
-
   // Split all the coroutines.
   for (LazyCallGraph::Node *N : Coroutines) {
     Function &F = N->getFunction();
@@ -2143,11 +2137,9 @@ PreservedAnalyses CoroSplitPass::run(LazyCallGraph::SCC &C,
     }
   }
 
-  if (!PrepareFns.empty()) {
     for (auto *PrepareFn : PrepareFns) {
       replaceAllPrepares(PrepareFn, CG, C);
     }
-  }
 
   return PreservedAnalyses::none();
 }

[ChuanqiXu9]

Why is this change NFC?

[yuxuanchen1997]

Because the next lines reads "for each coroutine in Coroutines". It's the same condition the if statement is checking for, then execute the exact same logic.

[ChuanqiXu9]

But it reads the PrepareFns, are they the same thing?

[yuxuanchen1997]

Oh sorry. I meant L2118 here. for (LazyCallGraph::Node *N : Coroutines) {

With and without this block, the executed logic is identical. With this block, this PrepareFns gets replaced with replaceAllPrepares on L2113. Without this block, if the Coroutines collection happens to be empty, it goes to the L2118 loop without any iteration, it goes to L2146 to perform the same logic.

[ChuanqiXu9]

Sounds good.

[yuxuanchen1997]

Sounds good.

Thanks.