[Flang]Fix for changed code at the end of AllocaIP. (#92430)

Some of the OpenMP code can change the instruction pointed at by the
insertion point. This leads to an assert in the compiler about
BB->getParent() and IP->getParent() not matching.

The fix is to rebuild the insertionpoint from the block, rather than use
builder.restoreIP.

Also, move some of the alloca generation, rather than skipping back and
forth between insert points (and ensure all the allocas are done before
their users are created).

A simple test, mainly to ensure the minimal reproducer doesn't fail to
compile in the future is also added.

Author: Leporacanthicus

clang/test/OpenMP/irbuilder_nested_parallel_for.c

@@ -545,17 +545,17 @@ int inline_decl() {
 // CHECK3-NEXT:    [[LOADGEP_I:%.*]] = load ptr, ptr [[GEP_I]], align 8
 // CHECK3-NEXT:    [[GEP_K:%.*]] = getelementptr { ptr, ptr }, ptr [[TMP0]], i32 0, i32 1
 // CHECK3-NEXT:    [[LOADGEP_K:%.*]] = load ptr, ptr [[GEP_K]], align 8
+// CHECK3-NEXT:    [[P_LASTITER:%.*]] = alloca i32, align 4
+// CHECK3-NEXT:    [[P_LOWERBOUND:%.*]] = alloca i32, align 4
+// CHECK3-NEXT:    [[P_UPPERBOUND:%.*]] = alloca i32, align 4
+// CHECK3-NEXT:    [[P_STRIDE:%.*]] = alloca i32, align 4
 // CHECK3-NEXT:    [[TID_ADDR_LOCAL:%.*]] = alloca i32, align 4
 // CHECK3-NEXT:    [[TMP1:%.*]] = load i32, ptr [[TID_ADDR]], align 4
 // CHECK3-NEXT:    store i32 [[TMP1]], ptr [[TID_ADDR_LOCAL]], align 4
 // CHECK3-NEXT:    [[TID:%.*]] = load i32, ptr [[TID_ADDR_LOCAL]], align 4
 // CHECK3-NEXT:    [[AGG_CAPTURED:%.*]] = alloca [[STRUCT_ANON:%.*]], align 8
 // CHECK3-NEXT:    [[AGG_CAPTURED1:%.*]] = alloca [[STRUCT_ANON_0:%.*]], align 4
 // CHECK3-NEXT:    [[DOTCOUNT_ADDR:%.*]] = alloca i32, align 4
-// CHECK3-NEXT:    [[P_LASTITER:%.*]] = alloca i32, align 4
-// CHECK3-NEXT:    [[P_LOWERBOUND:%.*]] = alloca i32, align 4
-// CHECK3-NEXT:    [[P_UPPERBOUND:%.*]] = alloca i32, align 4
-// CHECK3-NEXT:    [[P_STRIDE:%.*]] = alloca i32, align 4
 // CHECK3-NEXT:    br label [[OMP_PAR_REGION:%.*]]
 // CHECK3:       omp.par.region:
 // CHECK3-NEXT:    store i32 0, ptr [[LOADGEP_I]], align 4
@@ -713,6 +713,10 @@ int inline_decl() {
 // CHECK3-NEXT:    [[LOADGEP_I:%.*]] = load ptr, ptr [[GEP_I]], align 8
 // CHECK3-NEXT:    [[GEP_RES:%.*]] = getelementptr { ptr, ptr }, ptr [[TMP0]], i32 0, i32 1
 // CHECK3-NEXT:    [[LOADGEP_RES:%.*]] = load ptr, ptr [[GEP_RES]], align 8
+// CHECK3-NEXT:    [[P_LASTITER:%.*]] = alloca i32, align 4
+// CHECK3-NEXT:    [[P_LOWERBOUND:%.*]] = alloca i32, align 4
+// CHECK3-NEXT:    [[P_UPPERBOUND:%.*]] = alloca i32, align 4
+// CHECK3-NEXT:    [[P_STRIDE:%.*]] = alloca i32, align 4
 // CHECK3-NEXT:    [[TID_ADDR_LOCAL:%.*]] = alloca i32, align 4
 // CHECK3-NEXT:    [[TMP1:%.*]] = load i32, ptr [[TID_ADDR]], align 4
 // CHECK3-NEXT:    store i32 [[TMP1]], ptr [[TID_ADDR_LOCAL]], align 4
@@ -721,10 +725,6 @@ int inline_decl() {
 // CHECK3-NEXT:    [[AGG_CAPTURED:%.*]] = alloca [[STRUCT_ANON_1:%.*]], align 8
 // CHECK3-NEXT:    [[AGG_CAPTURED1:%.*]] = alloca [[STRUCT_ANON_2:%.*]], align 4
 // CHECK3-NEXT:    [[DOTCOUNT_ADDR:%.*]] = alloca i32, align 4
-// CHECK3-NEXT:    [[P_LASTITER:%.*]] = alloca i32, align 4
-// CHECK3-NEXT:    [[P_LOWERBOUND:%.*]] = alloca i32, align 4
-// CHECK3-NEXT:    [[P_UPPERBOUND:%.*]] = alloca i32, align 4
-// CHECK3-NEXT:    [[P_STRIDE:%.*]] = alloca i32, align 4
 // CHECK3-NEXT:    br label [[OMP_PAR_REGION:%.*]]
 // CHECK3:       omp.par.region:
 // CHECK3-NEXT:    store i32 0, ptr [[LOADGEP_I]], align 4
@@ -884,17 +884,17 @@ int inline_decl() {
 // CHECK4-NEXT:    [[LOADGEP_I:%.*]] = load ptr, ptr [[GEP_I]], align 8
 // CHECK4-NEXT:    [[GEP_K:%.*]] = getelementptr { ptr, ptr }, ptr [[TMP0]], i32 0, i32 1
 // CHECK4-NEXT:    [[LOADGEP_K:%.*]] = load ptr, ptr [[GEP_K]], align 8
+// CHECK4-NEXT:    [[P_LASTITER:%.*]] = alloca i32, align 4
+// CHECK4-NEXT:    [[P_LOWERBOUND:%.*]] = alloca i32, align 4
+// CHECK4-NEXT:    [[P_UPPERBOUND:%.*]] = alloca i32, align 4
+// CHECK4-NEXT:    [[P_STRIDE:%.*]] = alloca i32, align 4
 // CHECK4-NEXT:    [[TID_ADDR_LOCAL:%.*]] = alloca i32, align 4
 // CHECK4-NEXT:    [[TMP1:%.*]] = load i32, ptr [[TID_ADDR]], align 4
 // CHECK4-NEXT:    store i32 [[TMP1]], ptr [[TID_ADDR_LOCAL]], align 4
 // CHECK4-NEXT:    [[TID:%.*]] = load i32, ptr [[TID_ADDR_LOCAL]], align 4
 // CHECK4-NEXT:    [[AGG_CAPTURED:%.*]] = alloca [[STRUCT_ANON:%.*]], align 8
 // CHECK4-NEXT:    [[AGG_CAPTURED1:%.*]] = alloca [[STRUCT_ANON_0:%.*]], align 4
 // CHECK4-NEXT:    [[DOTCOUNT_ADDR:%.*]] = alloca i32, align 4
-// CHECK4-NEXT:    [[P_LASTITER:%.*]] = alloca i32, align 4
-// CHECK4-NEXT:    [[P_LOWERBOUND:%.*]] = alloca i32, align 4
-// CHECK4-NEXT:    [[P_UPPERBOUND:%.*]] = alloca i32, align 4
-// CHECK4-NEXT:    [[P_STRIDE:%.*]] = alloca i32, align 4
 // CHECK4-NEXT:    br label [[OMP_PAR_REGION:%.*]]
 // CHECK4:       omp.par.region:
 // CHECK4-NEXT:    store i32 0, ptr [[LOADGEP_I]], align 4, !dbg [[DBG23:![0-9]+]]
@@ -1062,6 +1062,10 @@ int inline_decl() {
 // CHECK4-NEXT:    [[LOADGEP_I:%.*]] = load ptr, ptr [[GEP_I]], align 8
 // CHECK4-NEXT:    [[GEP_RES:%.*]] = getelementptr { ptr, ptr }, ptr [[TMP0]], i32 0, i32 1
 // CHECK4-NEXT:    [[LOADGEP_RES:%.*]] = load ptr, ptr [[GEP_RES]], align 8
+// CHECK4-NEXT:    [[P_LASTITER:%.*]] = alloca i32, align 4
+// CHECK4-NEXT:    [[P_LOWERBOUND:%.*]] = alloca i32, align 4
+// CHECK4-NEXT:    [[P_UPPERBOUND:%.*]] = alloca i32, align 4
+// CHECK4-NEXT:    [[P_STRIDE:%.*]] = alloca i32, align 4
 // CHECK4-NEXT:    [[TID_ADDR_LOCAL:%.*]] = alloca i32, align 4
 // CHECK4-NEXT:    [[TMP1:%.*]] = load i32, ptr [[TID_ADDR]], align 4
 // CHECK4-NEXT:    store i32 [[TMP1]], ptr [[TID_ADDR_LOCAL]], align 4
@@ -1070,10 +1074,6 @@ int inline_decl() {
 // CHECK4-NEXT:    [[AGG_CAPTURED:%.*]] = alloca [[STRUCT_ANON_1:%.*]], align 8
 // CHECK4-NEXT:    [[AGG_CAPTURED1:%.*]] = alloca [[STRUCT_ANON_2:%.*]], align 4
 // CHECK4-NEXT:    [[DOTCOUNT_ADDR:%.*]] = alloca i32, align 4
-// CHECK4-NEXT:    [[P_LASTITER:%.*]] = alloca i32, align 4
-// CHECK4-NEXT:    [[P_LOWERBOUND:%.*]] = alloca i32, align 4
-// CHECK4-NEXT:    [[P_UPPERBOUND:%.*]] = alloca i32, align 4
-// CHECK4-NEXT:    [[P_STRIDE:%.*]] = alloca i32, align 4
 // CHECK4-NEXT:    br label [[OMP_PAR_REGION:%.*]]
 // CHECK4:       omp.par.region:
 // CHECK4-NEXT:    store i32 0, ptr [[LOADGEP_I]], align 4, !dbg [[DBG86:![0-9]+]]

clang/test/OpenMP/nested_loop_codegen.cpp

@@ -0,0 +1,48 @@
+!! Make sure that mixture of by-ref and by-val reductions work all the way
+!! to LLVM-IR code.
+! RUN: %flang_fc1 -emit-llvm -fopenmp -o - %s 2>&1 | FileCheck %s
+subroutine proc
+  implicit none
+  real(8),allocatable :: F(:)
+  real(8),allocatable :: A(:)
+   
+  integer :: I
+
+!$omp parallel private(A) reduction(+:F,I)
+  allocate(A(10))
+!$omp end parallel
+end subroutine proc
+
+!CHECK-LABEL: define void @proc_()
+!CHECK: call void
+!CHECK-SAME: @__kmpc_fork_call(ptr {{.*}}, i32 1, ptr @[[OMP_PAR:.*]], {{.*}})
+
+!CHECK: define internal void @[[OMP_PAR]](ptr {{.*}} %[[TID_ADDR:.*]], ptr noalias 
+!CHECK:  %[[TID_LOCAL:.*]] = alloca i32
+!CHECK:  %[[TID:.*]] = load i32, ptr %[[TID_ADDR]]
+!CHECK:  store i32 %[[TID]], ptr %[[TID_LOCAL]]
+!CHECK:  %[[I_priv:.*]] = alloca i32
+!CHECK:  %[[F_priv:.*]] = alloca ptr
+
+!CHECK: omp.reduction.init:
+!CHECK: store ptr %{{.*}}, ptr %[[F_priv]]
+!CHECK: store i32 0, ptr %[[I_priv]]
+
+!CHECK: omp.par.region8:
+!CHECK-NEXT: call ptr @malloc
+!CHECK-SAME: i64 10
+
+!CHECK: %[[RED_ARR_0:.*]] = getelementptr inbounds [2 x ptr], ptr %red.array, i64 0, i64 0
+!CHECK: store ptr %[[F_priv]], ptr %[[RED_ARR_0:.*]]
+!CHECK: %[[RED_ARR_1:.*]] = getelementptr inbounds [2 x ptr], ptr %red.array, i64 0, i64 1
+!CHECK: store ptr %[[I_priv]], ptr %[[RED_ARR_1]]
+
+!CHECK: omp.par.pre_finalize:                             ; preds = %reduce.finalize
+!CHECK:  %{{.*}} = load ptr, ptr %[[F_priv]]
+!CHECK:  br label %omp.reduction.cleanup
+
+!CHECK: omp.reduction.cleanup:
+!CHECK:  br i1 %{{.*}}, label %[[OMP_FREE:.*]], label %{{.*}}
+
+!CHECK: [[OMP_FREE]]:
+!CHECK: call void @free

flang/test/Lower/OpenMP/parallel-reduction-mixed.f90

@@ -1392,7 +1392,8 @@ IRBuilder<>::InsertPoint OpenMPIRBuilder::createParallel(
 
   // Change the location to the outer alloca insertion point to create and
   // initialize the allocas we pass into the parallel region.
-  Builder.restoreIP(OuterAllocaIP);
+  InsertPointTy NewOuter(OuterAllocaBlock, OuterAllocaBlock->begin());
+  Builder.restoreIP(NewOuter);
   AllocaInst *TIDAddrAlloca = Builder.CreateAlloca(Int32, nullptr, "tid.addr");
   AllocaInst *ZeroAddrAlloca =
       Builder.CreateAlloca(Int32, nullptr, "zero.addr");
@@ -2156,7 +2157,7 @@ OpenMPIRBuilder::createReductions(const LocationDescription &Loc,
   // values.
   unsigned NumReductions = ReductionInfos.size();
   Type *RedArrayTy = ArrayType::get(Builder.getPtrTy(), NumReductions);
-  Builder.restoreIP(AllocaIP);
+  Builder.SetInsertPoint(AllocaIP.getBlock()->getTerminator());
   Value *RedArray = Builder.CreateAlloca(RedArrayTy, nullptr, "red.array");
 
   Builder.SetInsertPoint(InsertBlock, InsertBlock->end());
@@ -2557,7 +2558,8 @@ OpenMPIRBuilder::applyStaticWorkshareLoop(DebugLoc DL, CanonicalLoopInfo *CLI,
       getOrCreateRuntimeFunction(M, omp::OMPRTL___kmpc_for_static_fini);
 
   // Allocate space for computed loop bounds as expected by the "init" function.
-  Builder.restoreIP(AllocaIP);
+  Builder.SetInsertPoint(AllocaIP.getBlock()->getFirstNonPHIOrDbgOrAlloca());
+
   Type *I32Type = Type::getInt32Ty(M.getContext());
   Value *PLastIter = Builder.CreateAlloca(I32Type, nullptr, "p.lastiter");
   Value *PLowerBound = Builder.CreateAlloca(IVTy, nullptr, "p.lowerbound");
@@ -3119,7 +3121,7 @@ OpenMPIRBuilder::InsertPointTy OpenMPIRBuilder::applyDynamicWorkshareLoop(
   FunctionCallee DynamicNext = getKmpcForDynamicNextForType(IVTy, M, *this);
 
   // Allocate space for computed loop bounds as expected by the "init" function.
-  Builder.restoreIP(AllocaIP);
+  Builder.SetInsertPoint(AllocaIP.getBlock()->getFirstNonPHIOrDbgOrAlloca());
   Type *I32Type = Type::getInt32Ty(M.getContext());
   Value *PLastIter = Builder.CreateAlloca(I32Type, nullptr, "p.lastiter");
   Value *PLowerBound = Builder.CreateAlloca(IVTy, nullptr, "p.lowerbound");

llvm/lib/Frontend/OpenMP/OMPIRBuilder.cpp

@@ -770,7 +770,7 @@ static void allocByValReductionVars(
     DenseMap<Value, llvm::Value *> &reductionVariableMap,
     llvm::ArrayRef<bool> isByRefs) {
   llvm::IRBuilderBase::InsertPointGuard guard(builder);
-  builder.restoreIP(allocaIP);
+  builder.SetInsertPoint(allocaIP.getBlock()->getTerminator());
   auto args =
       loop.getRegion().getArguments().take_back(loop.getNumReductionVars());
 
@@ -780,7 +780,7 @@ static void allocByValReductionVars(
     llvm::Value *var = builder.CreateAlloca(
         moduleTranslation.convertType(reductionDecls[i].getType()));
     moduleTranslation.mapValue(args[i], var);
-    privateReductionVariables.push_back(var);
+    privateReductionVariables[i] = var;
     reductionVariableMap.try_emplace(loop.getReductionVars()[i], var);
   }
 }
@@ -911,7 +911,8 @@ convertOmpWsloop(Operation &opInst, llvm::IRBuilderBase &builder,
   llvm::OpenMPIRBuilder::InsertPointTy allocaIP =
       findAllocaInsertPoint(builder, moduleTranslation);
 
-  SmallVector<llvm::Value *> privateReductionVariables;
+  SmallVector<llvm::Value *> privateReductionVariables(
+      wsloopOp.getNumReductionVars());
   DenseMap<Value, llvm::Value *> reductionVariableMap;
   allocByValReductionVars(wsloopOp, builder, moduleTranslation, allocaIP,
                           reductionDecls, privateReductionVariables,
@@ -942,7 +943,7 @@ convertOmpWsloop(Operation &opInst, llvm::IRBuilderBase &builder,
       // ptr
       builder.CreateStore(phis[0], var);
 
-      privateReductionVariables.push_back(var);
+      privateReductionVariables[i] = var;
       moduleTranslation.mapValue(reductionArgs[i], phis[0]);
       reductionVariableMap.try_emplace(wsloopOp.getReductionVars()[i], phis[0]);
     } else {
@@ -1140,7 +1141,8 @@ convertOmpParallel(omp::ParallelOp opInst, llvm::IRBuilderBase &builder,
   // Collect reduction declarations
   SmallVector<omp::DeclareReductionOp> reductionDecls;
   collectReductionDecls(opInst, reductionDecls);
-  SmallVector<llvm::Value *> privateReductionVariables;
+  SmallVector<llvm::Value *> privateReductionVariables(
+      opInst.getNumReductionVars());
 
   auto bodyGenCB = [&](InsertPointTy allocaIP, InsertPointTy codeGenIP) {
     // Allocate reduction vars
@@ -1154,6 +1156,21 @@ convertOmpParallel(omp::ParallelOp opInst, llvm::IRBuilderBase &builder,
     MutableArrayRef<BlockArgument> reductionArgs =
         opInst.getRegion().getArguments().take_back(
             opInst.getNumReductionVars());
+
+    llvm::BasicBlock *initBlock = splitBB(builder, true, "omp.reduction.init");
+    allocaIP =
+        InsertPointTy(allocaIP.getBlock(),
+                      allocaIP.getBlock()->getTerminator()->getIterator());
+    SmallVector<llvm::Value *> byRefVars(opInst.getNumReductionVars());
+    for (unsigned i = 0; i < opInst.getNumReductionVars(); ++i) {
+      if (isByRef[i]) {
+        // Allocate reduction variable (which is a pointer to the real reduciton
+        // variable allocated in the inlined region)
+        byRefVars[i] = builder.CreateAlloca(
+            moduleTranslation.convertType(reductionDecls[i].getType()));
+      }
+    }
+
     for (unsigned i = 0; i < opInst.getNumReductionVars(); ++i) {
       SmallVector<llvm::Value *> phis;
 
@@ -1166,18 +1183,14 @@ convertOmpParallel(omp::ParallelOp opInst, llvm::IRBuilderBase &builder,
       assert(phis.size() == 1 &&
              "expected one value to be yielded from the "
              "reduction neutral element declaration region");
-      builder.restoreIP(allocaIP);
+      builder.SetInsertPoint(initBlock->getTerminator());
 
       if (isByRef[i]) {
-        // Allocate reduction variable (which is a pointer to the real reduciton
-        // variable allocated in the inlined region)
-        llvm::Value *var = builder.CreateAlloca(
-            moduleTranslation.convertType(reductionDecls[i].getType()));
         // Store the result of the inlined region to the allocated reduction var
         // ptr
-        builder.CreateStore(phis[0], var);
+        builder.CreateStore(phis[0], byRefVars[i]);
 
-        privateReductionVariables.push_back(var);
+        privateReductionVariables[i] = byRefVars[i];
         moduleTranslation.mapValue(reductionArgs[i], phis[0]);
         reductionVariableMap.try_emplace(opInst.getReductionVars()[i], phis[0]);
       } else {

mlir/lib/Target/LLVMIR/Dialect/OpenMP/OpenMPToLLVMIRTranslation.cpp

@@ -55,11 +55,11 @@
 
 // Private reduction variable and its initialization.
 // CHECK: %tid.addr.local = alloca i32
-// CHECK: %[[MALLOC_I:.+]] = call ptr @malloc(i64 4)
 // CHECK: %[[PRIV_PTR_I:.+]] = alloca ptr
+// CHECK: %[[PRIV_PTR_J:.+]] = alloca ptr
+// CHECK: %[[MALLOC_I:.+]] = call ptr @malloc(i64 4)
 // CHECK: store ptr %[[MALLOC_I]], ptr %[[PRIV_PTR_I]]
 // CHECK: %[[MALLOC_J:.+]] = call ptr @malloc(i64 4)
-// CHECK: %[[PRIV_PTR_J:.+]] = alloca ptr
 // CHECK: store ptr %[[MALLOC_J]], ptr %[[PRIV_PTR_J]]
 
 // Call to the reduction function.

mlir/test/Target/LLVMIR/openmp-parallel-reduction-cleanup.mlir

@@ -59,13 +59,15 @@ module {
 // CHECK:         %[[VAL_17:.*]] = load i32, ptr %[[VAL_18:.*]], align 4
 // CHECK:         store i32 %[[VAL_17]], ptr %[[VAL_16]], align 4
 // CHECK:         %[[VAL_19:.*]] = load i32, ptr %[[VAL_16]], align 4
-// CHECK:         %[[VAL_20:.*]] = load { ptr, i64, i32, i8, i8, i8, i8, [1 x [3 x i64]] }, ptr %[[VAL_13]], align 8
 // CHECK:         %[[VAL_21:.*]] = alloca ptr, align 8
+// CHECK:         %[[VAL_23:.*]] = alloca ptr, align 8
+// CHECK:         %[[VAL_20:.*]] = load { ptr, i64, i32, i8, i8, i8, i8, [1 x [3 x i64]] }, ptr %[[VAL_13]], align 8
+// CHECK:         %[[VAL_24:.*]] = alloca [2 x ptr], align 8
+// CHECK:         br label %[[INIT_LABEL:.*]]
+// CHECK: [[INIT_LABEL]]:
 // CHECK:         store ptr %[[VAL_13]], ptr %[[VAL_21]], align 8
 // CHECK:         %[[VAL_22:.*]] = load { ptr, i64, i32, i8, i8, i8, i8, [1 x [3 x i64]] }, ptr %[[VAL_15]], align 8
-// CHECK:         %[[VAL_23:.*]] = alloca ptr, align 8
 // CHECK:         store ptr %[[VAL_15]], ptr %[[VAL_23]], align 8
-// CHECK:         %[[VAL_24:.*]] = alloca [2 x ptr], align 8
 // CHECK:         br label %[[VAL_25:.*]]
 // CHECK:       omp.par.region:                                   ; preds = %[[VAL_26:.*]]
 // CHECK:         br label %[[VAL_27:.*]]