[mlir] Migrate away from TypeRange(std::nullopt) (NFC)

[kazutakahirata]

ArrayRef has a constructor that accepts std::nullopt. This
constructor dates back to the days when we still had llvm::Optional.

Since the use of std::nullopt outside the context of std::optional is
kind of abuse and not intuitive to new comers, I would like to move
away from the constructor and eventually remove it.

One of the uses of std::nullopt is in a the constructors for
TypeRange. This patch takes care of the migration where we need
TypeRange() to facilitate perfect forwarding. Note that {} would be
ambiguous for perfecting forwarding to work.

[llvmbot]

@llvm/pr-subscribers-mlir-spirv
@llvm/pr-subscribers-mlir-gpu

@llvm/pr-subscribers-mlir

Author: Kazu Hirata (kazutakahirata)

Changes

ArrayRef has a constructor that accepts std::nullopt. This
constructor dates back to the days when we still had llvm::Optional.

Since the use of std::nullopt outside the context of std::optional is
kind of abuse and not intuitive to new comers, I would like to move
away from the constructor and eventually remove it.

One of the uses of std::nullopt is in a the constructors for
TypeRange. This patch takes care of the migration where we need
TypeRange() to facilitate perfect forwarding. Note that {} would be
ambiguous for perfecting forwarding to work.

---

Full diff: https://github.com/llvm/llvm-project/pull/145246.diff

3 Files Affected:

• (modified) mlir/lib/Conversion/SCFToGPU/SCFToGPU.cpp (+1-1)
• (modified) mlir/lib/Conversion/SPIRVToLLVM/SPIRVToLLVM.cpp (+1-1)
• (modified) mlir/test/lib/Dialect/Test/TestPatterns.cpp (+2-2)

diff --git a/mlir/lib/Conversion/SCFToGPU/SCFToGPU.cpp b/mlir/lib/Conversion/SCFToGPU/SCFToGPU.cpp
index 1ac95ebcdc87f..84959d5ff8aba 100644
--- a/mlir/lib/Conversion/SCFToGPU/SCFToGPU.cpp
+++ b/mlir/lib/Conversion/SCFToGPU/SCFToGPU.cpp
@@ -245,7 +245,7 @@ void AffineLoopToGpuConverter::createLaunch(AffineForOp rootForOp,
   Location terminatorLoc = terminator.getLoc();
   terminator.erase();
   builder.setInsertionPointToEnd(innermostForOp.getBody());
-  builder.create<gpu::TerminatorOp>(terminatorLoc, std::nullopt);
+  builder.create<gpu::TerminatorOp>(terminatorLoc, TypeRange());
   launchOp.getBody().front().getOperations().splice(
       launchOp.getBody().front().begin(),
       innermostForOp.getBody()->getOperations());
diff --git a/mlir/lib/Conversion/SPIRVToLLVM/SPIRVToLLVM.cpp b/mlir/lib/Conversion/SPIRVToLLVM/SPIRVToLLVM.cpp
index 93979e0f73324..2e4561e7cc3ea 100644
--- a/mlir/lib/Conversion/SPIRVToLLVM/SPIRVToLLVM.cpp
+++ b/mlir/lib/Conversion/SPIRVToLLVM/SPIRVToLLVM.cpp
@@ -839,7 +839,7 @@ class FunctionCallPattern
                   ConversionPatternRewriter &rewriter) const override {
     if (callOp.getNumResults() == 0) {
       auto newOp = rewriter.replaceOpWithNewOp<LLVM::CallOp>(
-          callOp, std::nullopt, adaptor.getOperands(), callOp->getAttrs());
+          callOp, TypeRange(), adaptor.getOperands(), callOp->getAttrs());
       newOp.getProperties().operandSegmentSizes = {
           static_cast<int32_t>(adaptor.getOperands().size()), 0};
       newOp.getProperties().op_bundle_sizes = rewriter.getDenseI32ArrayAttr({});
diff --git a/mlir/test/lib/Dialect/Test/TestPatterns.cpp b/mlir/test/lib/Dialect/Test/TestPatterns.cpp
index d073843484d81..a4cb705e6c8ea 100644
--- a/mlir/test/lib/Dialect/Test/TestPatterns.cpp
+++ b/mlir/test/lib/Dialect/Test/TestPatterns.cpp
@@ -1008,7 +1008,7 @@ struct TestPassthroughInvalidOp : public ConversionPattern {
                                   op->getOperand(it.index()).getType(), range)
               .getResult());
     }
-    rewriter.replaceOpWithNewOp<TestValidOp>(op, std::nullopt, flattened,
+    rewriter.replaceOpWithNewOp<TestValidOp>(op, TypeRange(), flattened,
                                              std::nullopt);
     return success();
   }
@@ -1024,7 +1024,7 @@ struct TestDropAndReplaceInvalidOp : public ConversionPattern {
   LogicalResult
   matchAndRewrite(Operation *op, ArrayRef<Value> operands,
                   ConversionPatternRewriter &rewriter) const final {
-    rewriter.replaceOpWithNewOp<TestValidOp>(op, std::nullopt, ValueRange(),
+    rewriter.replaceOpWithNewOp<TestValidOp>(op, TypeRange(), ValueRange(),
                                              std::nullopt);
     return success();
   }