[flang][NFC] use tablegen to create StackArrays constructor

[tblah]

Stack arrays needs to stay running only on func.func because it needs to know which block terminators can end the function (rather than just branch between unstructured control flow). A similar concept does not exist at the more abstract level of "any top level mlir operation".

For example, it currently looks for func::ReturnOp and fir::UnreachableOp as points when execution can end. If this were to be run on omp.declare_reduction, it would also need to understand omp.YieldOp (perhaps only when omp.declare_reduction is the parent). There isn't a generic concept in MLIR for this.

[llvmbot]

@llvm/pr-subscribers-flang-fir-hlfir

Author: Tom Eccles (tblah)

Changes

Stack arrays needs to stay running only on func.func because it needs to know which block terminators can end the function (rather than just branch between unstructured control flow). A similar concept does not exist at the more abstract level of "any top level mlir operation".

For example, it currently looks for func::ReturnOp and fir::UnreachableOp as points when execution can end. If this were to be run on omp.declare_reduction, it would also need to understand omp.YieldOp (perhaps only when omp.declare_reduction is the parent). There isn't a generic concept in MLIR for this.

---

Full diff: https://github.com/llvm/llvm-project/pull/90038.diff

4 Files Affected:

• (modified) flang/include/flang/Optimizer/Transforms/Passes.h (+1-1)
• (modified) flang/include/flang/Optimizer/Transforms/Passes.td (-1)
• (modified) flang/include/flang/Tools/CLOptions.inc (+1-1)
• (modified) flang/lib/Optimizer/Transforms/StackArrays.cpp (-4)

diff --git a/flang/include/flang/Optimizer/Transforms/Passes.h b/flang/include/flang/Optimizer/Transforms/Passes.h
index fd7a4a3883c996..76396ac96eecb1 100644
--- a/flang/include/flang/Optimizer/Transforms/Passes.h
+++ b/flang/include/flang/Optimizer/Transforms/Passes.h
@@ -47,6 +47,7 @@ namespace fir {
 #define GEN_PASS_DECL_POLYMORPHICOPCONVERSION
 #define GEN_PASS_DECL_OPENACCDATAOPERANDCONVERSION
 #define GEN_PASS_DECL_ADDDEBUGINFO
+#define GEN_PASS_DECL_STACKARRAYS
 #include "flang/Optimizer/Transforms/Passes.h.inc"
 
 std::unique_ptr<mlir::Pass> createAffineDemotionPass();
@@ -58,7 +59,6 @@ createExternalNameConversionPass(bool appendUnderscore);
 std::unique_ptr<mlir::Pass> createMemDataFlowOptPass();
 std::unique_ptr<mlir::Pass> createPromoteToAffinePass();
 std::unique_ptr<mlir::Pass> createMemoryAllocationPass();
-std::unique_ptr<mlir::Pass> createStackArraysPass();
 std::unique_ptr<mlir::Pass> createAliasTagsPass();
 std::unique_ptr<mlir::Pass>
 createAddDebugInfoPass(fir::AddDebugInfoOptions options = {});
diff --git a/flang/include/flang/Optimizer/Transforms/Passes.td b/flang/include/flang/Optimizer/Transforms/Passes.td
index c3d5c336af40ba..0b2d274ee74348 100644
--- a/flang/include/flang/Optimizer/Transforms/Passes.td
+++ b/flang/include/flang/Optimizer/Transforms/Passes.td
@@ -257,7 +257,6 @@ def StackArrays : Pass<"stack-arrays", "mlir::ModuleOp"> {
     allocations.
   }];
   let dependentDialects = [ "fir::FIROpsDialect" ];
-  let constructor = "::fir::createStackArraysPass()";
 }
 
 def AddAliasTags : Pass<"fir-add-alias-tags", "mlir::ModuleOp"> {
diff --git a/flang/include/flang/Tools/CLOptions.inc b/flang/include/flang/Tools/CLOptions.inc
index f24716333d9acf..aaee1f67567e52 100644
--- a/flang/include/flang/Tools/CLOptions.inc
+++ b/flang/include/flang/Tools/CLOptions.inc
@@ -258,7 +258,7 @@ inline void createDefaultFIROptimizerPassPipeline(
   pm.addPass(mlir::createCSEPass());
 
   if (pc.StackArrays)
-    pm.addPass(fir::createStackArraysPass());
+    pm.addPass(fir::createStackArrays());
   else
     fir::addMemoryAllocationOpt(pm);
 
diff --git a/flang/lib/Optimizer/Transforms/StackArrays.cpp b/flang/lib/Optimizer/Transforms/StackArrays.cpp
index 1c213abefe6f5f..c81524dd16a77e 100644
--- a/flang/lib/Optimizer/Transforms/StackArrays.cpp
+++ b/flang/lib/Optimizer/Transforms/StackArrays.cpp
@@ -776,7 +776,3 @@ void StackArraysPass::runOnFunc(mlir::Operation *func) {
     signalPassFailure();
   }
 }
-
-std::unique_ptr<mlir::Pass> fir::createStackArraysPass() {
-  return std::make_unique<StackArraysPass>();
-}

[clementval]

LGTM. Thanks for the cleanup