[CodeGen] Basic block sections should take precendence over splitting.

The use of basic block sections should take precedence over the machine
function splitting pass. Since they use the same underlying mechanism
they are kept exclusive. Updated the tests to check that split machine
functions is overridden by all flavours of basic block sections.

Differential Revision: https://reviews.llvm.org/D96392

1 files changed, 7 insertions, 5 deletions

diff --git a/llvm/lib/CodeGen/TargetPassConfig.cpp b/llvm/lib/CodeGen/TargetPassConfig.cpp
index e844d03..30b58e6 100644
--- a/llvm/lib/CodeGen/TargetPassConfig.cpp
+++ b/llvm/lib/CodeGen/TargetPassConfig.cpp
@@ -1187,12 +1187,14 @@ void TargetPassConfig::addMachinePasses() {
   }
 
   // Machine function splitter uses the basic block sections feature. Both
-  // cannot be enabled at the same time.
-  if (TM->Options.EnableMachineFunctionSplitter ||
-      EnableMachineFunctionSplitter) {
-    addPass(createMachineFunctionSplitterPass());
-  } else if (TM->getBBSectionsType() != llvm::BasicBlockSection::None) {
+  // cannot be enabled at the same time. Basic block sections takes precedence.
+  // FIXME: In principle, BasicBlockSection::Labels and splitting can used
+  // together. Update this check once we have addressed any issues.
+  if (TM->getBBSectionsType() != llvm::BasicBlockSection::None) {
     addPass(llvm::createBasicBlockSectionsPass(TM->getBBSectionsFuncListBuf()));
+  } else if (TM->Options.EnableMachineFunctionSplitter ||
+             EnableMachineFunctionSplitter) {
+    addPass(createMachineFunctionSplitterPass());
   }
 
   // Add passes that directly emit MI after all other MI passes.