Skeletonupstream/users/clang_cir_cfg

author: Jasmine Tang <jjasmine@igalia.com> 2025-11-13 11:39:38 -0800
committer: Jasmine Tang <jjasmine@igalia.com> 2025-11-16 22:24:44 -0800
commit: 9c069eac2cd69aa3f35718dd0b83bee98f74262b (patch)
tree: 873d3c16779fa0b322983f746b6b4a18295f122d
parent: f5e2c5ddcec758ffdaff027a239a163331a73292 (diff)
6 files changed, 188 insertions, 0 deletions
diff --git a/clang/include/clang/CIR/Dialect/Passes.h b/clang/include/clang/CIR/Dialect/Passes.h
index 32c3e27d07df..4dba6b548029 100644
--- a/clang/include/clang/CIR/Dialect/Passes.h
+++ b/clang/include/clang/CIR/Dialect/Passes.h
@@ -27,6 +27,7 @@ std::unique_ptr<Pass> createHoistAllocasPass();
 std::unique_ptr<Pass> createLoweringPreparePass();
 std::unique_ptr<Pass> createLoweringPreparePass(clang::ASTContext *astCtx);
 std::unique_ptr<Pass> createGotoSolverPass();
+std::unique_ptr<Pass> createFallThroughWarningPass();
 
 void populateCIRPreLoweringPasses(mlir::OpPassManager &pm);
 
diff --git a/clang/include/clang/CIR/Dialect/Passes.td b/clang/include/clang/CIR/Dialect/Passes.td
index 0f5783945f8a..6e272ddeef85 100644
--- a/clang/include/clang/CIR/Dialect/Passes.td
+++ b/clang/include/clang/CIR/Dialect/Passes.td
@@ -93,4 +93,14 @@ def LoweringPrepare : Pass<"cir-lowering-prepare"> {
   let dependentDialects = ["cir::CIRDialect"];
 }
 
+def CFGFallThroughWarnings: Pass<"cir-fallthrough-warnings"> {
+  let summary = "This pass replicates "
+    "other dialects";
+  let description = [{
+    This pass does preparation work for lowering to other dialects. For example,
+    it may expand the global variable initialziation in a more ABI-friendly form.
+  }];
+  let constructor = "mlir::createFallThroughWarningPass()";
+  let dependentDialects = ["cir::CIRDialect"];
+}
 #endif // CLANG_CIR_DIALECT_PASSES_TD
diff --git a/clang/lib/CIR/Dialect/Analysis/CMakeLists.txt b/clang/lib/CIR/Dialect/Analysis/CMakeLists.txt
new file mode 100644
index 000000000000..27a5606d2570
--- /dev/null
+++ b/clang/lib/CIR/Dialect/Analysis/CMakeLists.txt
@@ -0,0 +1,18 @@
+add_clang_library(MLIRCIRAnalysis
+  FallThroughWarning.cpp
+
+  DEPENDS
+  MLIRCIRPassIncGen
+
+  LINK_LIBS PUBLIC
+  clangAST
+  clangBasic
+
+  MLIRAnalysis
+  MLIRIR
+  MLIRPass
+  MLIRTransformUtils
+
+  MLIRCIR
+  MLIRCIRInterfaces
+)
diff --git a/clang/lib/CIR/Dialect/Analysis/FallThroughWarning.cpp b/clang/lib/CIR/Dialect/Analysis/FallThroughWarning.cpp
new file mode 100644
index 000000000000..57cd6c5d78ff
--- /dev/null
+++ b/clang/lib/CIR/Dialect/Analysis/FallThroughWarning.cpp
@@ -0,0 +1,157 @@
+#include "mlir/IR/Block.h"
+#include "mlir/IR/Operation.h"
+#include "mlir/Support/LLVM.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/Analysis/AnalysisDeclContext.h"
+#include "clang/Basic/Module.h"
+#include "clang/Basic/SourceLocation.h"
+#include "clang/Basic/TargetInfo.h"
+#include "clang/CIR/Dialect/Builder/CIRBaseBuilder.h"
+#include "clang/CIR/Dialect/IR/CIRDialect.h"
+#include "clang/CIR/Dialect/IR/CIROpsEnums.h"
+#include "clang/CIR/Dialect/IR/CIRTypes.h"
+#include "clang/CIR/Dialect/Passes.h"
+#include "clang/CIR/MissingFeatures.h"
+#include "clang/Sema/Sema.h"
+#include "llvm/Support/Path.h"
+
+#include <memory>
+
+namespace mlir {
+#define GEN_PASS_DEF_CFGFALLTHROUGHWARNINGS
+#include "clang/CIR/Dialect/Passes.h.inc"
+} // namespace mlir
+using namespace mlir;
+using namespace cir;
+using namespace clang;
+
+namespace {
+
+//===----------------------------------------------------------------------===//
+// Check for missing return value.
+//===----------------------------------------------------------------------===//
+
+enum ControlFlowKind {
+  UnknownFallThrough,
+  NeverFallThrough,
+  MaybeFallThrough,
+  AlwaysFallThrough,
+  NeverFallThroughOrReturn
+};
+
+struct CheckFallThroughDiagnostics {
+  unsigned diagFallThroughHasNoReturn = 0;
+  unsigned diagFallThroughReturnsNonVoid = 0;
+  unsigned diagNeverFallThroughOrReturn = 0;
+  unsigned funKind;
+  SourceLocation funcLoc;
+  bool checkDiagnostics(DiagnosticsEngine &d, bool returnsVoid,
+                        bool hasNoReturn) const {
+    if (funKind == diag::FalloffFunctionKind::Function) {
+      return (returnsVoid ||
+              d.isIgnored(diag::warn_falloff_nonvoid, funcLoc)) &&
+             (!hasNoReturn ||
+              d.isIgnored(diag::warn_noreturn_has_return_expr, funcLoc)) &&
+             (!returnsVoid ||
+              d.isIgnored(diag::warn_suggest_noreturn_block, funcLoc));
+    }
+    if (funKind == diag::FalloffFunctionKind::Coroutine) {
+      return (returnsVoid ||
+              d.isIgnored(diag::warn_falloff_nonvoid, funcLoc)) &&
+             (!hasNoReturn);
+    }
+    // For blocks / lambdas.
+    return returnsVoid && !hasNoReturn;
+  }
+};
+// TODO: Add a class for fall through config later
+
+struct FallThroughWarningPass
+    : public impl::CFGFallThroughWarningsBase<FallThroughWarningPass> {
+public:
+  FallThroughWarningPass() = default;
+  void runOnOperation() override;
+  void checkFallThroughForFuncBody(Sema &s, cir::FuncOp func,
+                                   QualType blockType,
+                                   const CheckFallThroughDiagnostics &cd);
+  ControlFlowKind checkFallThrough(cir::FuncOp cfg);
+  mlir::DenseSet<mlir::Block> getLiveSet(cir::FuncOp cfg, bool getAll) {
+    mlir::DenseSet<mlir::Block> liveSet;
+    if (cfg.getBody().empty())
+      return liveSet;
+
+    auto &body = cfg.getBody();
+    auto &first = cfg.getBody().getBlocks().front();
+
+    for (auto &block : body) {
+      if (getAll || block.isReachable(&first))
+        liveSet.insert(block);
+    }
+    return liveSet;
+  }
+};
+
+// TODO: This runs on func op only
+void FallThroughWarningPass::runOnOperation() {
+  mlir::Operation *op = getOperation();
+  if (!isa<cir::FuncOp>(op))
+    return;
+}
+
+void FallThroughWarningPass::checkFallThroughForFuncBody(
+    Sema &s, cir::FuncOp cfg, QualType blockType,
+    const CheckFallThroughDiagnostics &cd) {
+  bool returnsVoid = false;
+  bool hasNoReturn = false;
+
+  // Supposedly all function in cir is FuncOp
+  // 1. If normal function (FunctionDecl), check if it's coroutine.
+  // 1a. if coroutine -> check the fallthrough handler (idk what this means,
+  // TODO for now)
+  if (cfg.getCoroutine()) {
+    // TODO: Let's not worry about coroutine for now
+  } else
+    returnsVoid = isa<cir::VoidType>(cfg.getFunctionType().getReturnType());
+
+  // TODO: Do we need to check for InferredNoReturnAttr just like in OG?
+  hasNoReturn = cfg.getFunctionType().getReturnTypes().empty();
+
+  DiagnosticsEngine &diags = s.getDiagnostics();
+  if (cd.checkDiagnostics(diags, returnsVoid, hasNoReturn)) {
+    return;
+  }
+
+  // cpu_dispatch functions permit empty function bodies for ICC compatibility.
+  // TODO: Do we have isCPUDispatchMultiVersion?
+
+
+
+}
+
+ControlFlowKind FallThroughWarningPass::checkFallThrough(cir::FuncOp cfg) {
+  assert(!cfg && "there can't be a null func op");
+
+  // TODO: Is no CFG akin to a declaration?
+  if (cfg.isDeclaration()) {
+    return UnknownFallThrough;
+  }
+
+  mlir::DenseSet<mlir::Block> liveSet =
+      this->getLiveSet(cfg, /*bool getAll=*/false);
+
+  unsigned count = liveSet.size();
+
+  bool hasLiveReturn = false;
+  bool hasFakeEdge = false;
+  bool hasPlainEdge = false;
+  bool hasAbnormalEdge = false;
+
+  // TODO: Do more here
+}
+} // namespace
+
+namespace mlir {
+std::unique_ptr<Pass> createFallThroughWarningPass() {
+  return std::make_unique<FallThroughWarningPass>();
+}
+} // namespace mlir
diff --git a/clang/lib/CIR/Dialect/CMakeLists.txt b/clang/lib/CIR/Dialect/CMakeLists.txt
index c825a61b2779..4c17fef0482e 100644
--- a/clang/lib/CIR/Dialect/CMakeLists.txt
+++ b/clang/lib/CIR/Dialect/CMakeLists.txt
@@ -1,3 +1,4 @@
 add_subdirectory(IR)
 add_subdirectory(OpenACC)
 add_subdirectory(Transforms)
+add_subdirectory(Analysis)
diff --git a/clang/lib/FrontendTool/CMakeLists.txt b/clang/lib/FrontendTool/CMakeLists.txt
index 66213f76eb96..0ad7141669d9 100644
--- a/clang/lib/FrontendTool/CMakeLists.txt
+++ b/clang/lib/FrontendTool/CMakeLists.txt
@@ -22,6 +22,7 @@ if(CLANG_ENABLE_CIR)
   list(APPEND link_libs
     clangCIRFrontendAction
     MLIRCIRTransforms
+    MLIRCIRAnalysis
     MLIRIR
     MLIRPass
     )
author	Jasmine Tang <jjasmine@igalia.com>	2025-11-13 11:39:38 -0800
committer	Jasmine Tang <jjasmine@igalia.com>	2025-11-16 22:24:44 -0800
commit	9c069eac2cd69aa3f35718dd0b83bee98f74262b (patch)
tree	873d3c16779fa0b322983f746b6b4a18295f122d
parent	f5e2c5ddcec758ffdaff027a239a163331a73292 (diff)