[CIR][NFC] Use TableGen to generate LLVM lowering patterns (#159390)

Most lowering patterns have exactly the same class declaration with
different names and different `matchAndRewrite` implementations, yet
their declaration occupies near 1000 lines of code in `LowerToLLVM.h`,
making this file difficult to read and boring to maintain. In this
patch, I migrate their declarations to be generated from `CIROps.td`
using `clang-tblgen`. Some extra `CIR_Op` TableGen fields are introduced
to help this:

- The `CIR_Op` class now defines a `bit` field `hasLLVMLowering` which
defaults to `true`. If its value is `true`, `clang-tblgen` would
generate an LLVM lowering pattern declaration for the operation.

- Some LLVM lowering patterns has bounded recursion. This could be
enabled by setting the `isLLVMLoweringRecursive` field in a `CIR_Op`
record to `true`.

- Some LLVM lowering patterns have defined additional class members.
They could be listed in the `extraLLVMLoweringPatternDecl` field.

Note that in the incubator we have a similar TableGen code generator
that generates LLVM lowering code for CIR builtin ops which has a
one-to-one correspondence to LLVM dialect operations. This patch does
NOT try to upstream it.

Some additional noticeable changes made by this patch:

- This patch adds the `dataLayout` member to every LLVM lowering pattern
class to make the job easier for a code generator. In the future we
might want to add more members to the lowering patterns, and we will
need to update the code generator to make such changes.

Author: Lancern

clang/include/clang/CIR/Dialect/IR/CIROps.td

@@ -78,7 +78,15 @@ class LLVMLoweringInfo {
 }
 
 class CIR_Op<string mnemonic, list<Trait> traits = []> :
-    Op<CIR_Dialect, mnemonic, traits>, LLVMLoweringInfo;
+    Op<CIR_Dialect, mnemonic, traits>, LLVMLoweringInfo {
+  // Should we generate an LLVM lowering pattern for this op?
+  bit hasLLVMLowering = true;
+  // Is the LLVM lowering pattern for this operation recursive?
+  bit isLLVMLoweringRecursive = false;
+  // Extra class declarations to be included in the generated LLVM lowering
+  // pattern.
+  code extraLLVMLoweringPatternDecl = "";
+}
 
 //===----------------------------------------------------------------------===//
 // CastOp
@@ -218,6 +226,10 @@ def CIR_CastOp : CIR_Op<"cast", [
   // The input and output types should match the cast kind.
   let hasVerifier = 1;
   let hasFolder = 1;
+
+  let extraLLVMLoweringPatternDecl = [{
+    mlir::Type convertTy(mlir::Type ty) const;
+  }];
 }
 
 
@@ -297,6 +309,8 @@ def CIR_ConstantOp : CIR_Op<"const", [
   }];
 
   let hasFolder = 1;
+
+  let isLLVMLoweringRecursive = true;
 }
 
 //===----------------------------------------------------------------------===//
@@ -613,6 +627,8 @@ def CIR_IfOp : CIR_Op<"if", [
       CArg<"BuilderCallbackRef", "buildTerminatedBody">:$thenBuilder,
       CArg<"BuilderCallbackRef", "nullptr">:$elseBuilder)>
   ];
+
+  let hasLLVMLowering = false;
 }
 
 //===----------------------------------------------------------------------===//
@@ -659,6 +675,7 @@ def CIR_ConditionOp : CIR_Op<"condition", [
   let arguments = (ins CIR_BoolType:$condition);
   let assemblyFormat = " `(` $condition `)` attr-dict ";
   let hasVerifier = 1;
+  let hasLLVMLowering = false;
 }
 
 //===----------------------------------------------------------------------===//
@@ -726,6 +743,8 @@ def CIR_YieldOp : CIR_Op<"yield", [
   let builders = [
     OpBuilder<(ins), [{ /* nothing to do */ }]>,
   ];
+
+  let hasLLVMLowering = false;
 }
 
 //===----------------------------------------------------------------------===//
@@ -741,6 +760,7 @@ def CIR_BreakOp : CIR_Op<"break", [Terminator]> {
   }];
   let assemblyFormat = "attr-dict";
   let hasVerifier = 1;
+  let hasLLVMLowering = false;
 }
 
 //===----------------------------------------------------------------------===//
@@ -756,6 +776,7 @@ def CIR_ContinueOp : CIR_Op<"continue", [Terminator]> {
   }];
   let assemblyFormat = "attr-dict";
   let hasVerifier = 1;
+  let hasLLVMLowering = false;
 }
 
 //===----------------------------------------------------------------------===//
@@ -814,6 +835,8 @@ def CIR_ScopeOp : CIR_Op<"scope", [
     // Scopes without yielding values.
     OpBuilder<(ins "llvm::function_ref<void(mlir::OpBuilder &, mlir::Location)>":$scopeBuilder)>
   ];
+
+  let hasLLVMLowering = false;
 }
 
 //===----------------------------------------------------------------------===//
@@ -860,6 +883,8 @@ def CIR_CaseOp : CIR_Op<"case", [
                    "CaseOpKind":$kind,
                    "mlir::OpBuilder::InsertPoint &":$insertPoint)>
   ];
+
+  let hasLLVMLowering = false;
 }
 
 def CIR_SwitchOp : CIR_Op<"switch", [
@@ -1025,6 +1050,8 @@ def CIR_SwitchOp : CIR_Op<"switch", [
     // This is an expensive and need to be used with caution.
     bool isSimpleForm(llvm::SmallVectorImpl<CaseOp> &cases);
   }];
+
+  let hasLLVMLowering = false;
 }
 
 //===----------------------------------------------------------------------===//
@@ -1170,6 +1197,8 @@ def CIR_GotoOp : CIR_Op<"goto", [Terminator]> {
   }];
   let arguments = (ins StrAttr:$label);
   let assemblyFormat = [{ $label attr-dict }];
+
+  let hasLLVMLowering = false;
 }
 
 //===----------------------------------------------------------------------===//
@@ -1185,6 +1214,8 @@ def CIR_LabelOp : CIR_Op<"label", [AlwaysSpeculatable]> {
   let arguments = (ins StrAttr:$label);
   let assemblyFormat = [{ $label attr-dict }];
   let hasVerifier = 1;
+
+  let hasLLVMLowering = false;
 }
 
 //===----------------------------------------------------------------------===//
@@ -1349,6 +1380,8 @@ def CIR_WhileOp : CIR_WhileOpBase<"while"> {
     }
     ```
   }];
+
+  let hasLLVMLowering = false;
 }
 
 def CIR_DoWhileOp : CIR_WhileOpBase<"do"> {
@@ -1375,6 +1408,8 @@ def CIR_DoWhileOp : CIR_WhileOpBase<"do"> {
     }
     ```
   }];
+
+  let hasLLVMLowering = false;
 }
 
 //===----------------------------------------------------------------------===//
@@ -1442,6 +1477,8 @@ def CIR_ForOp : CIR_LoopOpBase<"for"> {
       return llvm::SmallVector<mlir::Region *, 3>{&getCond(), &getBody(), &getStep()};
     }
   }];
+
+  let hasLLVMLowering = false;
 }
 
 //===----------------------------------------------------------------------===//
@@ -1480,6 +1517,8 @@ def CIR_CmpOp : CIR_Op<"cmp", [Pure, SameTypeOperands]> {
   let assemblyFormat = [{
     `(` $kind `,` $lhs `,` $rhs  `)` `:` type($lhs) `,` type($result) attr-dict
   }];
+
+  let isLLVMLoweringRecursive = true;
 }
 
 //===----------------------------------------------------------------------===//
@@ -1550,6 +1589,10 @@ def CIR_BinOp : CIR_Op<"binop", [
   }];
 
   let hasVerifier = 1;
+
+  let extraLLVMLoweringPatternDecl = [{
+    mlir::LLVM::IntegerOverflowFlags getIntOverflowFlag(cir::BinOp op) const;
+  }];
 }
 
 //===----------------------------------------------------------------------===//
@@ -1687,6 +1730,8 @@ def CIR_TernaryOp : CIR_Op<"ternary", [
       `false` $falseRegion
     `)` `:` functional-type(operands, results) attr-dict
   }];
+
+  let hasLLVMLowering = false;
 }
 
 //===----------------------------------------------------------------------===//
@@ -1790,6 +1835,20 @@ def CIR_GlobalOp : CIR_Op<"global", [
     "cir::GlobalLinkageKind::ExternalLinkage">:$linkage)>];
 
   let hasVerifier = 1;
+
+  let isLLVMLoweringRecursive = true;
+  let extraLLVMLoweringPatternDecl = [{
+    mlir::LogicalResult matchAndRewriteRegionInitializedGlobal(
+      cir::GlobalOp op, mlir::Attribute init,
+      mlir::ConversionPatternRewriter &rewriter) const;
+
+    void setupRegionInitializedLLVMGlobalOp(
+        cir::GlobalOp op, mlir::ConversionPatternRewriter &rewriter) const;
+
+    mutable mlir::LLVM::ComdatOp comdatOp = nullptr;
+    mlir::SymbolRefAttr getComdatAttr(cir::GlobalOp &op,
+                                      mlir::OpBuilder &builder) const;
+  }];
 }
 
 //===----------------------------------------------------------------------===//
@@ -2340,6 +2399,19 @@ def CIR_FuncOp : CIR_Op<"func", [
 
   let hasCustomAssemblyFormat = 1;
   let hasVerifier = 1;
+
+  let extraLLVMLoweringPatternDecl = [{
+    static mlir::StringRef getLinkageAttrNameString() { return "linkage"; }
+
+    void lowerFuncAttributes(
+        cir::FuncOp func, bool filterArgAndResAttrs,
+        mlir::SmallVectorImpl<mlir::NamedAttribute> &result) const;
+
+    mlir::LogicalResult
+    matchAndRewriteAlias(cir::FuncOp op, llvm::StringRef aliasee, mlir::Type ty,
+                         OpAdaptor adaptor,
+                         mlir::ConversionPatternRewriter &rewriter) const;
+  }];
 }
 
 //===----------------------------------------------------------------------===//
@@ -2761,6 +2833,8 @@ class CIR_ArrayInitDestroy<string mnemonic> : CIR_Op<mnemonic> {
         regionBuilder($_builder, $_state.location);
     }]>
   ];
+
+  let hasLLVMLowering = false;
 }
 
 def CIR_ArrayCtor : CIR_ArrayInitDestroy<"array.ctor"> {
@@ -3380,6 +3454,8 @@ def CIR_ComplexMulOp : CIR_Op<"complex.mul", [
   let assemblyFormat = [{
     $lhs `,` $rhs `range` `(` $range `)` `:` qualified(type($result)) attr-dict
   }];
+
+  let hasLLVMLowering = false;
 }
 
 def CIR_ComplexDivOp : CIR_Op<"complex.div", [
@@ -3422,6 +3498,8 @@ def CIR_ComplexDivOp : CIR_Op<"complex.div", [
   let assemblyFormat = [{
     $lhs `,` $rhs `range` `(` $range `)` `:` qualified(type($result)) attr-dict
   }];
+
+  let hasLLVMLowering = false;
 }
 
 //===----------------------------------------------------------------------===//

clang/include/clang/CIR/Dialect/IR/CMakeLists.txt

@@ -20,6 +20,10 @@ mlir_tablegen(CIROpsAttributes.h.inc -gen-attrdef-decls)
 mlir_tablegen(CIROpsAttributes.cpp.inc -gen-attrdef-defs)
 add_public_tablegen_target(MLIRCIREnumsGen)
 
+clang_tablegen(CIRLowering.inc -gen-cir-lowering
+               SOURCE CIROps.td
+               TARGET CIRLowering)
+
 set(LLVM_TARGET_DEFINITIONS CIRTypeConstraints.td)
 mlir_tablegen(CIRTypeConstraints.h.inc -gen-type-constraint-decls)
 mlir_tablegen(CIRTypeConstraints.cpp.inc -gen-type-constraint-defs)

clang/lib/CIR/Lowering/DirectToLLVM/LowerToLLVM.cpp

@@ -2463,87 +2463,11 @@ void ConvertCIRToLLVMPass::runOnOperation() {
 
   mlir::RewritePatternSet patterns(&getContext());
 
-  patterns.add<CIRToLLVMReturnOpLowering>(patterns.getContext());
-  // This could currently be merged with the group below, but it will get more
-  // arguments later, so we'll keep it separate for now.
-  patterns.add<CIRToLLVMAllocaOpLowering>(converter, patterns.getContext(), dl);
-  patterns.add<CIRToLLVMLoadOpLowering>(converter, patterns.getContext(), dl);
-  patterns.add<CIRToLLVMStoreOpLowering>(converter, patterns.getContext(), dl);
-  patterns.add<CIRToLLVMGlobalOpLowering>(converter, patterns.getContext(), dl);
-  patterns.add<CIRToLLVMCastOpLowering>(converter, patterns.getContext(), dl);
-  patterns.add<CIRToLLVMPtrStrideOpLowering>(converter, patterns.getContext(),
-                                             dl);
-  patterns.add<CIRToLLVMInlineAsmOpLowering>(converter, patterns.getContext(),
-                                             dl);
   patterns.add<
-      // clang-format off
-               CIRToLLVMACosOpLowering,
-               CIRToLLVMASinOpLowering,
-               CIRToLLVMAssumeOpLowering,
-               CIRToLLVMAssumeAlignedOpLowering,
-               CIRToLLVMAssumeSepStorageOpLowering,
-               CIRToLLVMAtomicCmpXchgLowering,
-               CIRToLLVMBaseClassAddrOpLowering,
-               CIRToLLVMATanOpLowering,
-               CIRToLLVMBinOpLowering,
-               CIRToLLVMBitClrsbOpLowering,
-               CIRToLLVMBitClzOpLowering,
-               CIRToLLVMBitCtzOpLowering,
-               CIRToLLVMBitFfsOpLowering,
-               CIRToLLVMBitParityOpLowering,
-               CIRToLLVMBitPopcountOpLowering,
-               CIRToLLVMBitReverseOpLowering,
-               CIRToLLVMBrCondOpLowering,
-               CIRToLLVMBrOpLowering,
-               CIRToLLVMByteSwapOpLowering,
-               CIRToLLVMCallOpLowering,
-               CIRToLLVMCmpOpLowering,
-               CIRToLLVMComplexAddOpLowering,
-               CIRToLLVMComplexCreateOpLowering,
-               CIRToLLVMComplexImagOpLowering,
-               CIRToLLVMComplexImagPtrOpLowering,
-               CIRToLLVMComplexRealOpLowering,
-               CIRToLLVMComplexRealPtrOpLowering,
-               CIRToLLVMComplexSubOpLowering,
-               CIRToLLVMCopyOpLowering,
-               CIRToLLVMCosOpLowering,
-               CIRToLLVMConstantOpLowering,
-               CIRToLLVMExpectOpLowering,
-               CIRToLLVMFAbsOpLowering,
-               CIRToLLVMFrameAddrOpLowering,
-               CIRToLLVMFuncOpLowering,
-               CIRToLLVMGetBitfieldOpLowering,
-               CIRToLLVMGetGlobalOpLowering,
-               CIRToLLVMGetMemberOpLowering,
-               CIRToLLVMReturnAddrOpLowering,
-               CIRToLLVMRotateOpLowering,
-               CIRToLLVMSelectOpLowering,
-               CIRToLLVMSetBitfieldOpLowering,
-               CIRToLLVMShiftOpLowering,
-               CIRToLLVMStackRestoreOpLowering,
-               CIRToLLVMStackSaveOpLowering,
-               CIRToLLVMSwitchFlatOpLowering,
-               CIRToLLVMThrowOpLowering,
-               CIRToLLVMTrapOpLowering,
-               CIRToLLVMUnaryOpLowering,
-               CIRToLLVMUnreachableOpLowering,
-               CIRToLLVMVAArgOpLowering,
-               CIRToLLVMVAEndOpLowering,
-               CIRToLLVMVAStartOpLowering,
-               CIRToLLVMVecCmpOpLowering,
-               CIRToLLVMVecCreateOpLowering,
-               CIRToLLVMVecExtractOpLowering,
-               CIRToLLVMVecInsertOpLowering,
-               CIRToLLVMVecShuffleDynamicOpLowering,
-               CIRToLLVMVecShuffleOpLowering,
-               CIRToLLVMVecSplatOpLowering,
-               CIRToLLVMVecTernaryOpLowering,
-               CIRToLLVMVTableAddrPointOpLowering,
-               CIRToLLVMVTableGetVPtrOpLowering,
-               CIRToLLVMVTableGetVirtualFnAddrOpLowering,
-               CIRToLLVMVTTAddrPointOpLowering
-      // clang-format on
-      >(converter, patterns.getContext());
+#define GET_LLVM_LOWERING_PATTERNS_LIST
+#include "clang/CIR/Dialect/IR/CIRLowering.inc"
+#undef GET_LLVM_LOWERING_PATTERNS_LIST
+      >(converter, patterns.getContext(), dl);
 
   processCIRAttrs(module);