[mlir][NFC] Replace some nested if with logical and.

[jacquesguan]

Summary

This patch replaces some nested if statement with logical and to reduce the nesting depth.

mlir/lib/Dialect/Arithmetic/IR/ArithmeticOps.cpp

OpFoldResult arith::CmpIOp::fold(ArrayRef<Attribute> operands) {
   // cmpi(pred, x, x)
   if (getLhs() == getRhs()) {
     auto val = applyCmpPredicateToEqualOperands(getPredicate());
     return getBoolAttribute(getType(), getContext(), val);
   }
 
   if (matchPattern(getRhs(), m_Zero())) {
     if (auto extOp = getLhs().getDefiningOp<ExtSIOp>()) {
-      if (extOp.getOperand().getType().cast<IntegerType>().getWidth() == 1) {
-        // extsi(%x : i1 -> iN) != 0  ->  %x
-        if (getPredicate() == arith::CmpIPredicate::ne) {
-          return extOp.getOperand();
-        }
-      }
-    }
+      if (extOp.getOperand().getType().cast<IntegerType>().getWidth() == 1 &&
+          getPredicate() == arith::CmpIPredicate::ne)
     if (auto extOp = getLhs().getDefiningOp<ExtUIOp>()) {
-      if (extOp.getOperand().getType().cast<IntegerType>().getWidth() == 1) {
-        // extui(%x : i1 -> iN) != 0  ->  %x
-        if (getPredicate() == arith::CmpIPredicate::ne) {
-          return extOp.getOperand();
-        }
-      }
-    }
-  }
+      if (extOp.getOperand().getType().cast<IntegerType>().getWidth() == 1 &&
+          getPredicate() == arith::CmpIPredicate::ne)
 
   auto lhs = operands.front().dyn_cast_or_null<IntegerAttr>();
   auto rhs = operands.back().dyn_cast_or_null<IntegerAttr>();
   if (!lhs || !rhs)
     return {};
 
   auto val = applyCmpPredicate(getPredicate(), lhs.getValue(), rhs.getValue());
   return BoolAttr::get(getContext(), val);
struct SelectToExtUI : public OpRewritePattern<arith::SelectOp> {
 
   LogicalResult matchAndRewrite(arith::SelectOp op,
                                 PatternRewriter &rewriter) const override {
     // Cannot extui i1 to i1, or i1 to f32
     if (!op.getType().isa<IntegerType>() || op.getType().isInteger(1))
       return failure();
 
     // select %x, c1, %c0 => extui %arg
-    if (matchPattern(op.getTrueValue(), m_One()))
-      if (matchPattern(op.getFalseValue(), m_Zero())) {
-        rewriter.replaceOpWithNewOp<arith::ExtUIOp>(op, op.getType(),
-                                                    op.getCondition());
-        return success();
-      }
+    if (matchPattern(op.getTrueValue(), m_One()) &&
+        matchPattern(op.getFalseValue(), m_Zero())) {
 
     // select %x, c0, %c1 => extui (xor %arg, true)
-    if (matchPattern(op.getTrueValue(), m_Zero()))
-      if (matchPattern(op.getFalseValue(), m_One())) {
-        rewriter.replaceOpWithNewOp<arith::ExtUIOp>(
-            op, op.getType(),
-            rewriter.create<arith::XOrIOp>(
-                op.getLoc(), op.getCondition(),
-                rewriter.create<arith::ConstantIntOp>(
-                    op.getLoc(), 1, op.getCondition().getType())));
-        return success();
-      }
+    if (matchPattern(op.getTrueValue(), m_Zero()) &&
+        matchPattern(op.getFalseValue(), m_One())) {
 
     return failure();
   }
 };
 
 void arith::SelectOp::getCanonicalizationPatterns(RewritePatternSet &results,
                                                   MLIRContext *context) {
   results.add<SelectI1Simplify, SelectToExtUI>(context);
OpFoldResult arith::SelectOp::fold(ArrayRef<Attribute> operands) {
   if (matchPattern(condition, m_One()))
     return trueVal;
 
   // select false, %0, %1 => %1
   if (matchPattern(condition, m_Zero()))
     return falseVal;
 
   // select %x, true, false => %x
-  if (getType().isInteger(1))
-    if (matchPattern(getTrueValue(), m_One()))
-      if (matchPattern(getFalseValue(), m_Zero()))
-        return condition;
+  if (getType().isInteger(1) && matchPattern(getTrueValue(), m_One()) &&
+      matchPattern(getFalseValue(), m_Zero()))
 
   if (auto cmp = dyn_cast_or_null<arith::CmpIOp>(condition.getDefiningOp())) {
     auto pred = cmp.getPredicate();
     if (pred == arith::CmpIPredicate::eq || pred == arith::CmpIPredicate::ne) {
       auto cmpLhs = cmp.getLhs();
       auto cmpRhs = cmp.getRhs();
 
       // %0 = arith.cmpi eq, %arg0, %arg1