[MLIR][OpenMP] Simplify OpenMP to LLVM dialect conversion (#132009)

This patch makes a few changes to unify the conversion process from the
'omp' to the 'llvm' dialect. The main goal of this change is to
consolidate the logic used to identify legal and illegal ops, and to
consolidate the conversion logic into a single class.

Changes introduced are the following:
- Removal of `getNumVariableOperands()` and `getVariableOperand()` extra
class declarations from OpenMP operations. These are redundant, as they
are equivalent to `mlir::Operation::getNumOperands()` and
`mlir::Operation::getOperands()`, respectively.
- Consolidation of `RegionOpConversion`,
`RegionLessOpWithVarOperandsConversion`,
`RegionOpWithVarOperandsConversion`, `RegionLessOpConversion`,
`AtomicReadOpConversion`, `MapInfoOpConversion`,
`DeclMapperOpConversion` and `MultiRegionOpConversion` into a single
`OpenMPOpConversion` class. This is possible because all of the previous
were doing parts of the same set of operations based on whether they
defined any regions, whether they took operands, type attributes, etc.
- Update of `mlir::configureOpenMPToLLVMConversionLegality` to use a
single generic set of checks for all operations, removing the need to
list every operation manually.
- Update of `mlir::populateOpenMPToLLVMConversionPatterns` to
automatically populate the list of patterns to include all dialect operations.

Author: skatrak

mlir/include/mlir/Dialect/OpenMP/OpenMPOps.td

@@ -891,17 +891,6 @@ def FlushOp : OpenMP_Op<"flush", clauses = [
 
   // Override inherited assembly format to include `varList`.
   let assemblyFormat = "( `(` $varList^ `:` type($varList) `)` )? attr-dict";
-
-  let extraClassDeclaration = [{
-    /// The number of variable operands.
-    unsigned getNumVariableOperands() {
-      return getOperation()->getNumOperands();
-    }
-    /// The i-th variable operand passed.
-    Value getVariableOperand(unsigned i) {
-      return getOperand(i);
-    }
-  }] # clausesExtraClassDeclaration;
 }
 
 //===----------------------------------------------------------------------===//
@@ -1001,18 +990,6 @@ def MapBoundsOp : OpenMP_Op<"map.bounds",
     ) attr-dict
   }];
 
-  let extraClassDeclaration = [{
-    /// The number of variable operands.
-    unsigned getNumVariableOperands() {
-      return getNumOperands();
-    }
-
-    /// The i-th variable operand passed.
-    Value getVariableOperand(unsigned i) {
-      return getOperands()[i];
-    }
-  }];
-
   let hasVerifier = 1;
 }
 
@@ -1098,18 +1075,6 @@ def MapInfoOp : OpenMP_Op<"map.info", [AttrSizedOperandSegments]> {
       | `bounds` `(` $bounds `)`
     ) `->` type($omp_ptr) attr-dict
   }];
-
-  let extraClassDeclaration = [{
-    /// The number of variable operands.
-    unsigned getNumVariableOperands() {
-      return getNumOperands();
-    }
-
-    /// The i-th variable operand passed.
-    Value getVariableOperand(unsigned i) {
-      return getOperands()[i];
-    }
-  }];
 }
 
 //===---------------------------------------------------------------------===//
@@ -1515,21 +1480,6 @@ def AtomicReadOp : OpenMP_Op<"atomic.read", traits = [
     clausesOptAssemblyFormat #
     ") `:` type($v) `,` type($x) `,` $element_type attr-dict";
 
-  let extraClassDeclaration = [{
-    /// The number of variable operands.
-    unsigned getNumVariableOperands() {
-      assert(getX() && "expected 'x' operand");
-      assert(getV() && "expected 'v' operand");
-      return 2;
-    }
-
-    /// The i-th variable operand passed.
-    Value getVariableOperand(unsigned i) {
-      assert(i < 2 && "invalid index position for an operand");
-      return i == 0 ? getX() : getV();
-    }
-  }] # clausesExtraClassDeclaration;
-
   let hasVerifier = 1;
 }
 
@@ -1555,21 +1505,6 @@ def AtomicWriteOp : OpenMP_Op<"atomic.write", traits = [
   let assemblyFormat = "$x `=` $expr" # clausesReqAssemblyFormat # " oilist(" #
     clausesOptAssemblyFormat # ") `:` type($x) `,` type($expr) attr-dict";
 
-  let extraClassDeclaration = [{
-    /// The number of variable operands.
-    unsigned getNumVariableOperands() {
-      assert(getX() && "expected address operand");
-      assert(getExpr() && "expected value operand");
-      return 2;
-    }
-
-    /// The i-th variable operand passed.
-    Value getVariableOperand(unsigned i) {
-      assert(i < 2 && "invalid index position for an operand");
-      return i == 0 ? getX() : getExpr();
-    }
-  }] # clausesExtraClassDeclaration;
-
   let hasVerifier = 1;
 }
 
@@ -1614,20 +1549,6 @@ def AtomicUpdateOp : OpenMP_Op<"atomic.update", traits = [
   let assemblyFormat = clausesAssemblyFormat #
     "$x `:` type($x) $region attr-dict";
 
-  let extraClassDeclaration = [{
-    /// The number of variable operands.
-    unsigned getNumVariableOperands() {
-      assert(getX() && "expected 'x' operand");
-      return 1;
-    }
-
-    /// The i-th variable operand passed.
-    Value getVariableOperand(unsigned i) {
-      assert(i == 0 && "invalid index position for an operand");
-      return getX();
-    }
-  }] # clausesExtraClassDeclaration;
-
   let hasVerifier = 1;
   let hasRegionVerifier = 1;
   let hasCanonicalizeMethod = 1;
@@ -1715,19 +1636,6 @@ def ThreadprivateOp : OpenMP_Op<"threadprivate",
   let assemblyFormat = [{
     $sym_addr `:` type($sym_addr) `->` type($tls_addr) attr-dict
   }];
-  let extraClassDeclaration = [{
-    /// The number of variable operands.
-    unsigned getNumVariableOperands() {
-      assert(getSymAddr() && "expected one variable operand");
-      return 1;
-    }
-
-    /// The i-th variable operand passed.
-    Value getVariableOperand(unsigned i) {
-      assert(i == 0 && "invalid index position for an operand");
-      return getSymAddr();
-    }
-  }];
 }
 
 //===----------------------------------------------------------------------===//