[flang][Transforms][NFC] Remove boilerplate from vscale range pass (#94598)

Use tablegen to generate the pass constructor.

This pass is supposed to add function attributes so it does not need to
operate on other top level operations.

Author: tblah

flang/include/flang/Optimizer/Transforms/Passes.h

@@ -54,6 +54,7 @@ namespace fir {
 #define GEN_PASS_DECL_OMPMAPINFOFINALIZATIONPASS
 #define GEN_PASS_DECL_OMPMARKDECLARETARGETPASS
 #define GEN_PASS_DECL_OMPFUNCTIONFILTERING
+#define GEN_PASS_DECL_VSCALEATTR
 #include "flang/Optimizer/Transforms/Passes.h.inc"
 
 std::unique_ptr<mlir::Pass> createAffineDemotionPass();

flang/include/flang/Optimizer/Transforms/Passes.td

@@ -359,7 +359,6 @@ def VScaleAttr : Pass<"vscale-attr", "mlir::func::FuncOp"> {
            "std::pair<unsigned, unsigned>", /*default=*/"std::pair<unsigned, unsigned>{}",
            "vector scale range">,
   ];
-  let constructor = "::fir::createVScaleAttrPass()";
 }
 
 def FunctionAttr : Pass<"function-attr", "mlir::func::FuncOp"> {

flang/include/flang/Tools/CLOptions.inc

@@ -369,7 +369,7 @@ inline void createDefaultFIRCodeGenPassPipeline(mlir::PassManager &pm,
   fir::createDebugPasses(pm, config.DebugInfo, config.OptLevel, inputFilename);
 
   if (config.VScaleMin != 0)
-    pm.addPass(fir::createVScaleAttrPass({config.VScaleMin, config.VScaleMax}));
+    pm.addPass(fir::createVScaleAttr({{config.VScaleMin, config.VScaleMax}}));
 
   // Add function attributes
   fir::FunctionAttrTypes functionAttrs;

flang/lib/Optimizer/Transforms/VScaleAttr.cpp

@@ -38,7 +38,6 @@
 #include <algorithm>
 
 namespace fir {
-#define GEN_PASS_DECL_VSCALEATTR
 #define GEN_PASS_DEF_VSCALEATTR
 #include "flang/Optimizer/Transforms/Passes.h.inc"
 } // namespace fir
@@ -77,14 +76,3 @@ void VScaleAttrPass::runOnOperation() {
 
   LLVM_DEBUG(llvm::dbgs() << "=== End " DEBUG_TYPE " ===\n");
 }
-
-std::unique_ptr<mlir::Pass>
-fir::createVScaleAttrPass(std::pair<unsigned, unsigned> vscaleAttr) {
-  VScaleAttrOptions opts;
-  opts.vscaleRange = vscaleAttr;
-  return std::make_unique<VScaleAttrPass>(opts);
-}
-
-std::unique_ptr<mlir::Pass> fir::createVScaleAttrPass() {
-  return std::make_unique<VScaleAttrPass>();
-}