Clean up trivially dead ops

flang/lib/Optimizer/OpenMP/LowerWorkshare.cpp

@@ -152,6 +152,14 @@ static bool isTransitivelyUsedOutside(Value v, SingleRegion sr) {
   return false;
 }
 
+/// We clone pure operations in both the parallel and single blocks. this
+/// functions cleans them up if they end up with no uses
+static void cleanupBlock(Block *block) {
+  for (Operation &op : llvm::make_early_inc_range(*block))
+    if (isOpTriviallyDead(&op))
+      op.erase();
+}
+
 static void parallelizeRegion(Region &sourceRegion, Region &targetRegion,
                               IRMapping &rootMapping, Location loc) {
   OpBuilder rootBuilder(sourceRegion.getContext());
@@ -258,13 +266,8 @@ static void parallelizeRegion(Region &sourceRegion, Region &targetRegion,
         singleOperands.copyprivateVars =
             moveToSingle(std::get<SingleRegion>(opOrSingle), allocaBuilder,
                          singleBuilder, parallelBuilder);
+        cleanupBlock(singleBlock);
         for (auto var : singleOperands.copyprivateVars) {
-          Type ty;
-          if (auto firAlloca = var.getDefiningOp<fir::AllocaOp>()) {
-            ty = firAlloca.getAllocatedType();
-          } else {
-            ty = LLVM::LLVMPointerType::get(allocaBuilder.getContext());
-          }
           mlir::func::FuncOp funcOp =
               createCopyFunc(loc, var.getType(), firCopyFuncBuilder);
           singleOperands.copyprivateSyms.push_back(SymbolRefAttr::get(funcOp));
@@ -302,6 +305,9 @@ static void parallelizeRegion(Region &sourceRegion, Region &targetRegion,
 
     rootBuilder.clone(*block.getTerminator(), rootMapping);
   }
+
+  for (Block &targetBlock : targetRegion)
+    cleanupBlock(&targetBlock);
 }
 
 /// Lowers workshare to a sequence of single-thread regions and parallel loops
@@ -372,20 +378,6 @@ class LowerWorksharePass
 
       lowerWorkshare(wsOp);
     });
-
-    // Do folding
-    for (Operation *isolatedParent : parents) {
-      RewritePatternSet patterns(&getContext());
-      GreedyRewriteConfig config;
-      // prevent the pattern driver form merging blocks
-      config.enableRegionSimplification =
-          mlir::GreedySimplifyRegionLevel::Disabled;
-      if (failed(applyPatternsAndFoldGreedily(isolatedParent,
-                                              std::move(patterns), config))) {
-        emitError(isolatedParent->getLoc(), "error in lower workshare\n");
-        signalPassFailure();
-      }
-    }
   }
 };
 } // namespace

flang/test/Transforms/OpenMP/lower-workshare3.mlir

@@ -3,7 +3,7 @@
 
 // tests if the correct values are stored
 
-func.func @wsfunc(%arg0: !fir.ref<!fir.array<42xi32>>) {
+func.func @wsfunc() {
   omp.parallel {
   // CHECK: fir.alloca
   // CHECK: fir.alloca

flang/test/Transforms/OpenMP/lower-workshare4.mlir

@@ -0,0 +1,55 @@
+// RUN: fir-opt --split-input-file --lower-workshare --allow-unregistered-dialect %s | FileCheck %s
+
+func.func @wsfunc() {
+  %a = fir.alloca i32
+  omp.parallel {
+    omp.workshare {
+      %t1 = "test.test1"() : () -> i32
+
+      %c1 = arith.constant 1 : index
+      %c42 = arith.constant 42 : index
+
+      %c2 = arith.constant 2 : index
+      "test.test3"(%c2) : (index) -> ()
+
+      "omp.workshare_loop_wrapper"() ({
+        omp.loop_nest (%arg1) : index = (%c1) to (%c42) inclusive step (%c1) {
+          "test.test2"() : () -> ()
+          omp.yield
+        }
+        omp.terminator
+      }) : () -> ()
+      omp.terminator
+    }
+    omp.terminator
+  }
+  return
+}
+
+// CHECK-LABEL:   func.func @wsfunc() {
+// CHECK:           %[[VAL_0:.*]] = fir.alloca i32
+// CHECK:           omp.parallel {
+// CHECK:             %[[VAL_1:.*]] = arith.constant true
+// CHECK:             fir.if %[[VAL_1]] {
+// CHECK:               omp.single {
+// CHECK:                 %[[VAL_2:.*]] = "test.test1"() : () -> i32
+// CHECK:                 %[[VAL_3:.*]] = arith.constant 2 : index
+// CHECK:                 "test.test3"(%[[VAL_3]]) : (index) -> ()
+// CHECK:                 omp.terminator
+// CHECK:               }
+// CHECK:               %[[VAL_4:.*]] = arith.constant 1 : index
+// CHECK:               %[[VAL_5:.*]] = arith.constant 42 : index
+// CHECK:               omp.wsloop nowait {
+// CHECK:                 omp.loop_nest (%[[VAL_6:.*]]) : index = (%[[VAL_4]]) to (%[[VAL_5]]) inclusive step (%[[VAL_4]]) {
+// CHECK:                   "test.test2"() : () -> ()
+// CHECK:                   omp.yield
+// CHECK:                 }
+// CHECK:                 omp.terminator
+// CHECK:               }
+// CHECK:               omp.barrier
+// CHECK:             }
+// CHECK:             omp.terminator
+// CHECK:           }
+// CHECK:           return
+// CHECK:         }
+