[Reg2Mem] Add legacy pass wrapping Reg2Mem

[Keenuts]

The SPIR-V backend will need to use Reg2Mem, hence this pass needs to be wrapped to be used with the legacy pass manager.

[llvmbot]

@llvm/pr-subscribers-llvm-transforms

Author: Nathan Gauër (Keenuts)

Changes

The SPIR-V backend will need to use Reg2Mem, hence this pass needs to be wrapped to be used with the legacy pass manager.

---

Full diff: https://github.com/llvm/llvm-project/pull/111024.diff

2 Files Affected:

• (modified) llvm/include/llvm/Transforms/Scalar/Reg2Mem.h (+25)
• (modified) llvm/lib/Transforms/Scalar/Reg2Mem.cpp (+28)

diff --git a/llvm/include/llvm/Transforms/Scalar/Reg2Mem.h b/llvm/include/llvm/Transforms/Scalar/Reg2Mem.h
index 25f6563d7dcfc2..f7815ca9a9a18c 100644
--- a/llvm/include/llvm/Transforms/Scalar/Reg2Mem.h
+++ b/llvm/include/llvm/Transforms/Scalar/Reg2Mem.h
@@ -13,7 +13,11 @@
 #ifndef LLVM_TRANSFORMS_SCALAR_REG2MEM_H
 #define LLVM_TRANSFORMS_SCALAR_REG2MEM_H
 
+#include "llvm/Analysis/LoopInfo.h"
+#include "llvm/IR/Dominators.h"
 #include "llvm/IR/PassManager.h"
+#include "llvm/InitializePasses.h"
+#include "llvm/Pass.h"
 
 namespace llvm {
 
@@ -22,6 +26,27 @@ class RegToMemPass : public PassInfoMixin<RegToMemPass> {
   PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM);
 };
 
+class RegToMemWrapperPass : public FunctionPass {
+public:
+  static char ID;
+
+  RegToMemWrapperPass();
+
+  void getAnalysisUsage(AnalysisUsage &AU) const override {
+    AU.setPreservesAll();
+
+    AU.addPreserved<DominatorTreeWrapperPass>();
+    AU.addRequired<DominatorTreeWrapperPass>();
+
+    AU.addPreserved<LoopInfoWrapperPass>();
+    AU.addRequired<LoopInfoWrapperPass>();
+  }
+
+  bool runOnFunction(Function &F) override;
+};
+
+FunctionPass *createRegToMemWrapperPass();
+
 } // end namespace llvm
 
 #endif // LLVM_TRANSFORMS_SCALAR_REG2MEM_H
diff --git a/llvm/lib/Transforms/Scalar/Reg2Mem.cpp b/llvm/lib/Transforms/Scalar/Reg2Mem.cpp
index ebc5075aa36fe8..33ae5faeba1198 100644
--- a/llvm/lib/Transforms/Scalar/Reg2Mem.cpp
+++ b/llvm/lib/Transforms/Scalar/Reg2Mem.cpp
@@ -105,3 +105,31 @@ PreservedAnalyses RegToMemPass::run(Function &F, FunctionAnalysisManager &AM) {
   PA.preserve<LoopAnalysis>();
   return PA;
 }
+
+namespace llvm {
+void initializeRegToMemWrapperPassPass(PassRegistry &);
+} // namespace llvm
+
+INITIALIZE_PASS_BEGIN(RegToMemWrapperPass, "reg-to-mem", "", true, true)
+INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass);
+INITIALIZE_PASS_DEPENDENCY(LoopInfoWrapperPass);
+INITIALIZE_PASS_END(RegToMemWrapperPass, "reg-to-mem", "", true, true)
+
+char RegToMemWrapperPass::ID = 0;
+
+RegToMemWrapperPass::RegToMemWrapperPass() : FunctionPass(ID) {}
+
+bool RegToMemWrapperPass::runOnFunction(Function &F) {
+  DominatorTree *DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
+  LoopInfo *LI = &getAnalysis<LoopInfoWrapperPass>().getLoopInfo();
+
+  unsigned N = SplitAllCriticalEdges(F, CriticalEdgeSplittingOptions(DT, LI));
+  bool Changed = runPass(F);
+  if (N == 0 && !Changed)
+    return false;
+  return true;
+}
+
+FunctionPass *llvm::createRegToMemWrapperPass() {
+  return new RegToMemWrapperPass();
+}

[Keenuts]

Hi! Here is some additional context on where we plan on using Reg2Mem pass if you need:
#111026

[Keenuts]

Thanks! Moved to cpp, and renamed the pass to reg2mem.

[nikic]

LGTM

[Keenuts]

Added the header functions to be able to instantiate it.

[Keenuts]

Back from holiday! Thanks for the review. Rebased on main, will wait for green CI and local tests & submit.