[nvq++] Removes MLIR's scf dialect

We don't use this dialect and its presence is a historical artifact.
This change triggered the removal of two tests:

* `test/Quake/ghz.qke`
* `test/Quake/iqft.qke`

Both tests are a reminder of a past when we had to write quantum kernels
directly in MLIR because of a lack of frontend. Both no longer test
aything useful.

The commit modifies `test/Quake/canonical-2.qke`, which was only testing
the canonicalization of `cc.scope` operations. The new form is removes
the clutter, making the test more precise.

`test/Translate/ghz.qke` had to be modified because it uses MLIR's
`affined.for` and its conversion to LLVMDialect requires `scf.for`.

Signed-off-by: boschmitt <[email protected]>

include/cudaq/Optimizer/InitAllDialects.h

@@ -18,7 +18,6 @@
 #include "mlir/Dialect/LLVMIR/LLVMDialect.h"
 #include "mlir/Dialect/Math/IR/Math.h"
 #include "mlir/Dialect/MemRef/IR/MemRef.h"
-#include "mlir/Dialect/SCF/IR/SCF.h"
 
 namespace cudaq {
 
@@ -35,7 +34,6 @@ inline void registerAllDialects(mlir::DialectRegistry &registry) {
     mlir::LLVM::LLVMDialect,
     mlir::math::MathDialect,
     mlir::memref::MemRefDialect,
-    mlir::scf::SCFDialect,
 
     // NVQ++ dialects
     cudaq::cc::CCDialect,

lib/Frontend/nvqpp/ConvertExpr.cpp

@@ -13,7 +13,6 @@
 #include "cudaq/Optimizer/Dialect/CC/CCOps.h"
 #include "cudaq/Optimizer/Dialect/Quake/QuakeOps.h"
 #include "llvm/Support/Debug.h"
-#include "mlir/Dialect/SCF/IR/SCF.h"
 
 #define DEBUG_TYPE "lower-ast-expr"
 

lib/Optimizer/CodeGen/CMakeLists.txt

@@ -62,7 +62,6 @@ add_cudaq_library(OptCodeGen
     MLIRFuncToLLVM
     MLIRMathToFuncs
     MLIRMathToLLVM
-    MLIRSCFToControlFlow
 
     # Translation
     MLIRTargetLLVMIRExport

lib/Optimizer/CodeGen/ConvertCCToLLVM.cpp

@@ -22,7 +22,6 @@
 #include "mlir/Conversion/LLVMCommon/Pattern.h"
 #include "mlir/Conversion/LLVMCommon/TypeConverter.h"
 #include "mlir/Conversion/MathToLLVM/MathToLLVM.h"
-#include "mlir/Conversion/SCFToControlFlow/SCFToControlFlow.h"
 #include "mlir/Dialect/Arith/Transforms/Passes.h"
 #include "mlir/Target/LLVMIR/TypeToLLVM.h"
 
@@ -121,7 +120,6 @@ struct CCToLLVM : public cudaq::opt::impl::CCToLLVMBase<CCToLLVM> {
     arith::populateArithToLLVMConversionPatterns(ccTypeConverter, patterns);
     populateMathToLLVMConversionPatterns(ccTypeConverter, patterns);
 
-    populateSCFToControlFlowConversionPatterns(patterns);
     cf::populateControlFlowToLLVMConversionPatterns(ccTypeConverter, patterns);
     populateFuncToLLVMConversionPatterns(ccTypeConverter, patterns);
     cudaq::opt::populateCCToLLVMPatterns(ccTypeConverter, patterns);

lib/Optimizer/CodeGen/ConvertToQIR.cpp

@@ -30,7 +30,6 @@
 #include "mlir/Conversion/LLVMCommon/Pattern.h"
 #include "mlir/Conversion/LLVMCommon/TypeConverter.h"
 #include "mlir/Conversion/MathToLLVM/MathToLLVM.h"
-#include "mlir/Conversion/SCFToControlFlow/SCFToControlFlow.h"
 #include "mlir/Dialect/Arith/Transforms/Passes.h"
 #include "mlir/Dialect/Complex/IR/Complex.h"
 #include "mlir/Target/LLVMIR/ModuleTranslation.h"
@@ -172,7 +171,6 @@ class ConvertToQIR : public cudaq::opt::impl::ConvertToQIRBase<ConvertToQIR> {
     arith::populateArithToLLVMConversionPatterns(typeConverter, patterns);
     populateMathToLLVMConversionPatterns(typeConverter, patterns);
 
-    populateSCFToControlFlowConversionPatterns(patterns);
     cf::populateControlFlowToLLVMConversionPatterns(typeConverter, patterns);
     populateFuncToLLVMConversionPatterns(typeConverter, patterns);
     cudaq::opt::populateCCToLLVMPatterns(typeConverter, patterns);

lib/Optimizer/Transforms/ApplyOpSpecialization.cpp

@@ -13,7 +13,6 @@
 #include "cudaq/Optimizer/Transforms/Passes.h"
 #include "cudaq/Todo.h"
 #include "llvm/Support/Debug.h"
-#include "mlir/Dialect/SCF/IR/SCF.h"
 #include "mlir/IR/Dominance.h"
 #include "mlir/IR/IRMapping.h"
 #include "mlir/Transforms/DialectConversion.h"
@@ -558,11 +557,6 @@ class ApplySpecializationPass
         invert(newIfOp.getElseRegion());
         continue;
       }
-      if (auto forOp = dyn_cast<scf::ForOp>(op)) {
-        LLVM_DEBUG(llvm::dbgs() << "moving for: " << forOp << ".\n");
-        TODO_loc(loc, "cannot make adjoint of kernel with scf.for");
-        // should we convert to cc.loop and use code below?
-      }
       if (auto loopOp = dyn_cast<cudaq::cc::LoopOp>(op)) {
         LLVM_DEBUG(llvm::dbgs() << "moving loop: " << loopOp << ".\n");
         auto newLoopOp = cloneReversedLoop(builder, loopOp);

test/Quake/canonical-2.qke

@@ -8,54 +8,29 @@
 
 // RUN: cudaq-opt -canonicalize %s | FileCheck %s
 
-  func.func @__nvqpp__mlirgen__reflect_about_uniform(%arg0: !quake.veq<?>) attributes {"cudaq-kernel"} {
-    %0 = quake.veq_size %arg0 : (!quake.veq<?>) -> i64
-    %c1_i32 = arith.constant 1 : i32
-    %1 = arith.extsi %c1_i32 : i32 to i64
-    %2 = arith.subi %0, %1 : i64
-    %c0_i64 = arith.constant 0 : i64
-    %c1_i64 = arith.constant 1 : i64
-    %3 = arith.subi %2, %c1_i64 : i64
-    %4 = quake.subveq %arg0, %c0_i64, %3 : (!quake.veq<?>, i64, i64) -> !quake.veq<?>
-    %5 = quake.veq_size %arg0 : (!quake.veq<?>) -> i64
-    %c1_i64_0 = arith.constant 1 : i64
-    %6 = arith.subi %5, %c1_i64_0 : i64
-    %7 = quake.extract_ref %arg0[%6] : (!quake.veq<?>,i64) -> !quake.ref
-    %8 = cc.create_lambda {
-      cc.scope {
-        %c0 = arith.constant 0 : index
-        %c1 = arith.constant 1 : index
-        %10 = quake.veq_size %arg0 : (!quake.veq<?>) -> i64
-        %11 = arith.index_cast %10 : i64 to index
-        scf.for %arg1 = %c0 to %11 step %c1 {
-          %12 = quake.extract_ref %arg0[%arg1] : (!quake.veq<?>,index) -> !quake.ref
-          quake.h %12 : (!quake.ref) -> ()
-        }
-      }
-    } : !cc.callable<() -> ()>
-    %9 = cc.create_lambda {
-      cc.scope {
-        quake.z [%4] %7 : (!quake.veq<?>, !quake.ref) -> ()
-      }
-    } : !cc.callable<() -> ()>
-    quake.compute_action %8, %9 : !cc.callable<() -> ()>, !cc.callable<() -> ()>
-    return
-  }
+func.func @canonicalize_scope(%arg0: !quake.ref) attributes {"cudaq-kernel"} {
+  %0 = cc.create_lambda {
+    cc.scope {
+      quake.h %arg0 : (!quake.ref) -> ()
+    }
+  } : !cc.callable<() -> ()>
+  %1 = cc.create_lambda {
+    cc.scope {
+      quake.z %arg0 : (!quake.ref) -> ()
+    }
+  } : !cc.callable<() -> ()>
+  quake.compute_action %0, %1 : !cc.callable<() -> ()>, !cc.callable<() -> ()>
+  return
+}
 
-// CHECK-LABEL:   func.func @__nvqpp__mlirgen__reflect_about_uniform(
-// CHECK:           %[[VAL_12:.*]] = cc.create_lambda {
+// CHECK-LABEL:   func.func @canonicalize_scope(
+// CHECK:           %[[VAL_0:.*]] = cc.create_lambda {
 // CHECK-NOT:       cc.scope
-// CHECK:             %[[VAL_13:.*]] = quake.veq_size %{{.*}} : (!quake.veq<?>) -> i64
-// CHECK:             %[[VAL_14:.*]] = arith.index_cast %[[VAL_13]] : i64 to index
-// CHECK:             scf.for %[[VAL_15:.*]] = %{{.*}} to %[[VAL_14]] step %
-// CHECK:               %[[VAL_16:.*]] = quake.extract_ref
-// CHECK:               quake.h %[[VAL_16]]
-// CHECK:             }
+// CHECK:             quake.h %{{.*}} :
 // CHECK:           } : !cc.callable<() -> ()>
-// CHECK:           %[[VAL_17:.*]] = cc.create_lambda {
+// CHECK:           %[[VAL_1:.*]] = cc.create_lambda {
 // CHECK-NOT:       cc.scope
-// CHECK:             quake.z [%{{.*}}] %{{.*}} :
+// CHECK:             quake.z %{{.*}} :
 // CHECK:           } : !cc.callable<() -> ()>
-// CHECK:           quake.compute_action
-// CHECK:           return
+// CHECK:           quake.compute_action %[[VAL_0]], %[[VAL_1]]