[OpenCL] Simplify LLVM IR generated for OpenCL blocks

Summary:
Emit direct call of block invoke functions when possible, i.e. in case the
block is not passed as a function argument.
Also doing some refactoring of `CodeGenFunction::EmitBlockCallExpr()`

Reviewers: Anastasia, yaxunl, svenvh

Reviewed By: Anastasia

Subscribers: cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D58388

llvm-svn: 354568

clang/lib/CodeGen/CGBlocks.cpp

@@ -1253,53 +1253,50 @@ RValue CodeGenFunction::EmitBlockCallExpr(const CallExpr *E,
                                           ReturnValueSlot ReturnValue) {
   const BlockPointerType *BPT =
     E->getCallee()->getType()->getAs<BlockPointerType>();
-
   llvm::Value *BlockPtr = EmitScalarExpr(E->getCallee());
-
-  // Get a pointer to the generic block literal.
-  // For OpenCL we generate generic AS void ptr to be able to reuse the same
-  // block definition for blocks with captures generated as private AS local
-  // variables and without captures generated as global AS program scope
-  // variables.
-  unsigned AddrSpace = 0;
-  if (getLangOpts().OpenCL)
-    AddrSpace = getContext().getTargetAddressSpace(LangAS::opencl_generic);
-
-  llvm::Type *BlockLiteralTy =
-      llvm::PointerType::get(CGM.getGenericBlockLiteralType(), AddrSpace);
-
-  // Bitcast the callee to a block literal.
-  BlockPtr =
-      Builder.CreatePointerCast(BlockPtr, BlockLiteralTy, "block.literal");
-
-  // Get the function pointer from the literal.
-  llvm::Value *FuncPtr =
-      Builder.CreateStructGEP(CGM.getGenericBlockLiteralType(), BlockPtr,
-                              CGM.getLangOpts().OpenCL ? 2 : 3);
-
-  // Add the block literal.
+  llvm::Type *GenBlockTy = CGM.getGenericBlockLiteralType();
+  llvm::Value *Func = nullptr;
+  QualType FnType = BPT->getPointeeType();
+  ASTContext &Ctx = getContext();
   CallArgList Args;
 
-  QualType VoidPtrQualTy = getContext().VoidPtrTy;
-  llvm::Type *GenericVoidPtrTy = VoidPtrTy;
   if (getLangOpts().OpenCL) {
-    GenericVoidPtrTy = CGM.getOpenCLRuntime().getGenericVoidPointerType();
-    VoidPtrQualTy =
-        getContext().getPointerType(getContext().getAddrSpaceQualType(
-            getContext().VoidTy, LangAS::opencl_generic));
+    // For OpenCL, BlockPtr is already casted to generic block literal.
+
+    // First argument of a block call is a generic block literal casted to
+    // generic void pointer, i.e. i8 addrspace(4)*
+    llvm::Value *BlockDescriptor = Builder.CreatePointerCast(
+        BlockPtr, CGM.getOpenCLRuntime().getGenericVoidPointerType());
+    QualType VoidPtrQualTy = Ctx.getPointerType(
+        Ctx.getAddrSpaceQualType(Ctx.VoidTy, LangAS::opencl_generic));
+    Args.add(RValue::get(BlockDescriptor), VoidPtrQualTy);
+    // And the rest of the arguments.
+    EmitCallArgs(Args, FnType->getAs<FunctionProtoType>(), E->arguments());
+
+    // We *can* call the block directly unless it is a function argument.
+    if (!isa<ParmVarDecl>(E->getCalleeDecl()))
+      Func = CGM.getOpenCLRuntime().getInvokeFunction(E->getCallee());
+    else {
+      llvm::Value *FuncPtr = Builder.CreateStructGEP(GenBlockTy, BlockPtr, 2);
+      Func = Builder.CreateAlignedLoad(FuncPtr, getPointerAlign());
+    }
+  } else {
+    // Bitcast the block literal to a generic block literal.
+    BlockPtr = Builder.CreatePointerCast(
+        BlockPtr, llvm::PointerType::get(GenBlockTy, 0), "block.literal");
+    // Get pointer to the block invoke function
+    llvm::Value *FuncPtr = Builder.CreateStructGEP(GenBlockTy, BlockPtr, 3);
+
+    // First argument is a block literal casted to a void pointer
+    BlockPtr = Builder.CreatePointerCast(BlockPtr, VoidPtrTy);
+    Args.add(RValue::get(BlockPtr), Ctx.VoidPtrTy);
+    // And the rest of the arguments.
+    EmitCallArgs(Args, FnType->getAs<FunctionProtoType>(), E->arguments());
+
+    // Load the function.
+    Func = Builder.CreateAlignedLoad(FuncPtr, getPointerAlign());
   }
 
-  BlockPtr = Builder.CreatePointerCast(BlockPtr, GenericVoidPtrTy);
-  Args.add(RValue::get(BlockPtr), VoidPtrQualTy);
-
-  QualType FnType = BPT->getPointeeType();
-
-  // And the rest of the arguments.
-  EmitCallArgs(Args, FnType->getAs<FunctionProtoType>(), E->arguments());
-
-  // Load the function.
-  llvm::Value *Func = Builder.CreateAlignedLoad(FuncPtr, getPointerAlign());
-
   const FunctionType *FuncTy = FnType->castAs<FunctionType>();
   const CGFunctionInfo &FnInfo =
     CGM.getTypes().arrangeBlockFunctionCall(Args, FuncTy);

clang/lib/CodeGen/CGOpenCLRuntime.cpp

@@ -122,6 +122,23 @@ llvm::PointerType *CGOpenCLRuntime::getGenericVoidPointerType() {
       CGM.getContext().getTargetAddressSpace(LangAS::opencl_generic));
 }
 
+// Get the block literal from an expression derived from the block expression.
+// OpenCL v2.0 s6.12.5:
+// Block variable declarations are implicitly qualified with const. Therefore
+// all block variables must be initialized at declaration time and may not be
+// reassigned.
+static const BlockExpr *getBlockExpr(const Expr *E) {
+  const Expr *Prev = nullptr; // to make sure we do not stuck in infinite loop.
+  while(!isa<BlockExpr>(E) && E != Prev) {
+    Prev = E;
+    E = E->IgnoreCasts();
+    if (auto DR = dyn_cast<DeclRefExpr>(E)) {
+      E = cast<VarDecl>(DR->getDecl())->getInit();
+    }
+  }
+  return cast<BlockExpr>(E);
+}
+
 /// Record emitted llvm invoke function and llvm block literal for the
 /// corresponding block expression.
 void CGOpenCLRuntime::recordBlockInfo(const BlockExpr *E,
@@ -136,20 +153,17 @@ void CGOpenCLRuntime::recordBlockInfo(const BlockExpr *E,
   EnqueuedBlockMap[E].Kernel = nullptr;
 }
 
+llvm::Function *CGOpenCLRuntime::getInvokeFunction(const Expr *E) {
+  return EnqueuedBlockMap[getBlockExpr(E)].InvokeFunc;
+}
+
 CGOpenCLRuntime::EnqueuedBlockInfo
 CGOpenCLRuntime::emitOpenCLEnqueuedBlock(CodeGenFunction &CGF, const Expr *E) {
   CGF.EmitScalarExpr(E);
 
   // The block literal may be assigned to a const variable. Chasing down
   // to get the block literal.
-  if (auto DR = dyn_cast<DeclRefExpr>(E)) {
-    E = cast<VarDecl>(DR->getDecl())->getInit();
-  }
-  E = E->IgnoreImplicit();
-  if (auto Cast = dyn_cast<CastExpr>(E)) {
-    E = Cast->getSubExpr();
-  }
-  auto *Block = cast<BlockExpr>(E);
+  const BlockExpr *Block = getBlockExpr(E);
 
   assert(EnqueuedBlockMap.find(Block) != EnqueuedBlockMap.end() &&
          "Block expression not emitted");

clang/lib/CodeGen/CGOpenCLRuntime.h

@@ -91,6 +91,10 @@ public:
   /// \param Block block literal emitted for the block expression.
   void recordBlockInfo(const BlockExpr *E, llvm::Function *InvokeF,
                        llvm::Value *Block);
+
+  /// \return LLVM block invoke function emitted for an expression derived from
+  /// the block expression.
+  llvm::Function *getInvokeFunction(const Expr *E);
 };
 
 }

clang/test/CodeGenOpenCL/blocks.cl

@@ -39,11 +39,8 @@ void foo(){
   // SPIR: %[[blk_gen_ptr:.*]] = addrspacecast %struct.__opencl_block_literal_generic* %[[blk_ptr]] to %struct.__opencl_block_literal_generic addrspace(4)*
   // SPIR: store %struct.__opencl_block_literal_generic addrspace(4)* %[[blk_gen_ptr]], %struct.__opencl_block_literal_generic addrspace(4)** %[[block_B:.*]],
   // SPIR: %[[block_literal:.*]] = load %struct.__opencl_block_literal_generic addrspace(4)*, %struct.__opencl_block_literal_generic addrspace(4)** %[[block_B]]
-  // SPIR: %[[invoke_addr:.*]] = getelementptr inbounds %struct.__opencl_block_literal_generic, %struct.__opencl_block_literal_generic addrspace(4)* %[[block_literal]], i32 0, i32 2
   // SPIR: %[[blk_gen_ptr:.*]] = bitcast %struct.__opencl_block_literal_generic addrspace(4)* %[[block_literal]] to i8 addrspace(4)*
-  // SPIR: %[[invoke_func_ptr:.*]] = load i8 addrspace(4)*, i8 addrspace(4)* addrspace(4)* %[[invoke_addr]]
-  // SPIR: %[[invoke_func:.*]] = addrspacecast i8 addrspace(4)* %[[invoke_func_ptr]] to i32 (i8 addrspace(4)*)*
-  // SPIR: call {{.*}}i32 %[[invoke_func]](i8 addrspace(4)* %[[blk_gen_ptr]])
+  // SPIR: call {{.*}}i32 @__foo_block_invoke(i8 addrspace(4)* %[[blk_gen_ptr]])
   // AMDGCN: %[[block_invoke:.*]] = getelementptr inbounds <{ i32, i32, i8*, i32 }>, <{ i32, i32, i8*, i32 }> addrspace(5)* %[[block:.*]], i32 0, i32 2
   // AMDGCN: store i8* bitcast (i32 (i8*)* @__foo_block_invoke to i8*), i8* addrspace(5)* %[[block_invoke]]
   // AMDGCN: %[[block_captured:.*]] = getelementptr inbounds <{ i32, i32, i8*, i32 }>, <{ i32, i32, i8*, i32 }> addrspace(5)* %[[block]], i32 0, i32 3
@@ -53,11 +50,8 @@ void foo(){
   // AMDGCN: %[[blk_gen_ptr:.*]] = addrspacecast %struct.__opencl_block_literal_generic addrspace(5)* %[[blk_ptr]] to %struct.__opencl_block_literal_generic*
   // AMDGCN: store %struct.__opencl_block_literal_generic* %[[blk_gen_ptr]], %struct.__opencl_block_literal_generic* addrspace(5)* %[[block_B:.*]],
   // AMDGCN: %[[block_literal:.*]] = load %struct.__opencl_block_literal_generic*, %struct.__opencl_block_literal_generic* addrspace(5)* %[[block_B]]
-  // AMDGCN: %[[invoke_addr:.*]] = getelementptr inbounds %struct.__opencl_block_literal_generic, %struct.__opencl_block_literal_generic* %[[block_literal]], i32 0, i32 2
   // AMDGCN: %[[blk_gen_ptr:.*]] = bitcast %struct.__opencl_block_literal_generic* %[[block_literal]] to i8*
-  // AMDGCN: %[[invoke_func_ptr:.*]] = load i8*, i8** %[[invoke_addr]]
-  // AMDGCN: %[[invoke_func:.*]] = bitcast i8* %[[invoke_func_ptr]] to i32 (i8*)*
-  // AMDGCN: call {{.*}}i32 %[[invoke_func]](i8* %[[blk_gen_ptr]])
+  // AMDGCN: call {{.*}}i32 @__foo_block_invoke(i8* %[[blk_gen_ptr]])
 
   int (^ block_B)(void) = ^{
     return i;

clang/test/CodeGenOpenCL/cl20-device-side-enqueue.cl

@@ -312,9 +312,7 @@ kernel void device_side_enqueue(global int *a, global int *b, int i) {
   };
 
   // Uses global block literal [[BLG8]] and invoke function [[INVG8]].
-  // COMMON: [[r1:%.*]] = load i8 addrspace(4)*, i8 addrspace(4)* addrspace(4)* getelementptr inbounds (%struct.__opencl_block_literal_generic, %struct.__opencl_block_literal_generic addrspace(4)* addrspacecast (%struct.__opencl_block_literal_generic addrspace(1)* bitcast ({ i32, i32, i8 addrspace(4)* } addrspace(1)* [[BLG8]] to %struct.__opencl_block_literal_generic addrspace(1)*) to %struct.__opencl_block_literal_generic addrspace(4)*), i32 0, i32 2)
-  // COMMON: [[r2:%.*]] = addrspacecast i8 addrspace(4)* [[r1]] to void (i8 addrspace(4)*)*
-  // COMMON: call spir_func void [[r2]](i8 addrspace(4)* addrspacecast (i8 addrspace(1)* bitcast ({ i32, i32, i8 addrspace(4)* } addrspace(1)* [[BLG8]] to i8 addrspace(1)*) to i8 addrspace(4)*))
+  // COMMON: call spir_func void @__device_side_enqueue_block_invoke_11(i8 addrspace(4)* addrspacecast (i8 addrspace(1)* bitcast ({ i32, i32, i8 addrspace(4)* } addrspace(1)* [[BLG8]] to i8 addrspace(1)*) to i8 addrspace(4)*))
   block_A();
 
   // Emits global block literal [[BLG8]] and block kernel [[INVGK8]]. [[INVGK8]] calls [[INVG8]].
@@ -333,15 +331,35 @@ kernel void device_side_enqueue(global int *a, global int *b, int i) {
   unsigned size = get_kernel_work_group_size(block_A);
 
   // Uses global block literal [[BLG8]] and invoke function [[INVG8]]. Make sure no redundant block literal and invoke functions are emitted.
-  // COMMON: [[r1:%.*]] = load i8 addrspace(4)*, i8 addrspace(4)* addrspace(4)* getelementptr inbounds (%struct.__opencl_block_literal_generic, %struct.__opencl_block_literal_generic addrspace(4)* addrspacecast (%struct.__opencl_block_literal_generic addrspace(1)* bitcast ({ i32, i32, i8 addrspace(4)* } addrspace(1)* [[BLG8]] to %struct.__opencl_block_literal_generic addrspace(1)*) to %struct.__opencl_block_literal_generic addrspace(4)*), i32 0, i32 2)
-  // COMMON: [[r2:%.*]] = addrspacecast i8 addrspace(4)* [[r1]] to void (i8 addrspace(4)*)*
-  // COMMON: call spir_func void [[r2]](i8 addrspace(4)* addrspacecast (i8 addrspace(1)* bitcast ({ i32, i32, i8 addrspace(4)* } addrspace(1)* [[BLG8]] to i8 addrspace(1)*) to i8 addrspace(4)*))
+  // COMMON: call spir_func void @__device_side_enqueue_block_invoke_11(i8 addrspace(4)* addrspacecast (i8 addrspace(1)* bitcast ({ i32, i32, i8 addrspace(4)* } addrspace(1)* [[BLG8]] to i8 addrspace(1)*) to i8 addrspace(4)*))
   block_A();
 
+  // Make sure that block invoke function is resolved correctly after sequence of assignements.
+  // COMMON: store %struct.__opencl_block_literal_generic addrspace(4)*
+  // COMMON-SAME: addrspacecast (%struct.__opencl_block_literal_generic addrspace(1)*
+  // COMMON-SAME: bitcast ({ i32, i32, i8 addrspace(4)* } addrspace(1)* [[BL_GLOBAL]] to %struct.__opencl_block_literal_generic addrspace(1)*)
+  // COMMON-SAME: to %struct.__opencl_block_literal_generic addrspace(4)*),
+  // COMMON-SAME: %struct.__opencl_block_literal_generic addrspace(4)** %b1,
+  bl_t b1 = block_G;
+  // COMMON: store %struct.__opencl_block_literal_generic addrspace(4)*
+  // COMMON-SAME: addrspacecast (%struct.__opencl_block_literal_generic addrspace(1)*
+  // COMMON-SAME: bitcast ({ i32, i32, i8 addrspace(4)* } addrspace(1)* [[BL_GLOBAL]] to %struct.__opencl_block_literal_generic addrspace(1)*)
+  // COMMON-SAME: to %struct.__opencl_block_literal_generic addrspace(4)*),
+  // COMMON-SAME: %struct.__opencl_block_literal_generic addrspace(4)** %b2,
+  bl_t b2 = b1;
+  // COMMON: call spir_func void @block_G_block_invoke(i8 addrspace(4)* addrspacecast (i8 addrspace(1)*
+  // COMMON-SAME: bitcast ({ i32, i32, i8 addrspace(4)* } addrspace(1)* [[BL_GLOBAL]] to i8 addrspace(1)*)
+  // COOMON-SAME: to i8 addrspace(4)*), i8 addrspace(3)* null)
+  b2(0);
+  // Uses global block literal [[BL_GLOBAL]] and block kernel [[INV_G_K]]. [[INV_G_K]] calls [[INV_G]].
+  // COMMON: call i32 @__get_kernel_preferred_work_group_size_multiple_impl(
+  // COMMON-SAME: i8 addrspace(4)* addrspacecast (i8* bitcast ({{.*}} [[INV_G_K:[^ ]+_kernel]] to i8*) to i8 addrspace(4)*),
+  // COMMON-SAME: i8 addrspace(4)* addrspacecast (i8 addrspace(1)* bitcast ({ i32, i32, i8 addrspace(4)* } addrspace(1)* [[BL_GLOBAL]] to i8 addrspace(1)*) to i8 addrspace(4)*))
+  size = get_kernel_preferred_work_group_size_multiple(b2);
+
   void (^block_C)(void) = ^{
     callee(i, a);
   };
-
   // Emits block literal on stack and block kernel [[INVLK3]].
   // COMMON: store i8 addrspace(4)* addrspacecast (i8* bitcast (void (i8 addrspace(4)*)* [[INVL3:@__device_side_enqueue_block_invoke[^ ]*]] to i8*) to i8 addrspace(4)*), i8 addrspace(4)** %block.invoke
   // COMMON: [[DEF_Q:%[0-9]+]] = load %opencl.queue_t{{.*}}*, %opencl.queue_t{{.*}}** %default_queue
@@ -404,8 +422,8 @@ kernel void device_side_enqueue(global int *a, global int *b, int i) {
 // COMMON: define internal spir_func void [[INVG8]](i8 addrspace(4)*{{.*}})
 // COMMON: define internal spir_func void [[INVG9]](i8 addrspace(4)*{{.*}}, i8 addrspace(3)* %{{.*}})
 // COMMON: define internal spir_kernel void [[INVGK8]](i8 addrspace(4)*{{.*}})
+// COMMON: define internal spir_kernel void [[INV_G_K]](i8 addrspace(4)*{{.*}}, i8 addrspace(3)*{{.*}})
 // COMMON: define internal spir_kernel void [[INVLK3]](i8 addrspace(4)*{{.*}})
 // COMMON: define internal spir_kernel void [[INVGK9]](i8 addrspace(4)*{{.*}}, i8 addrspace(3)*{{.*}})
-// COMMON: define internal spir_kernel void [[INV_G_K]](i8 addrspace(4)*{{.*}}, i8 addrspace(3)*{{.*}})
 // COMMON: define internal spir_kernel void [[INVGK10]](i8 addrspace(4)*{{.*}})
 // COMMON: define internal spir_kernel void [[INVGK11]](i8 addrspace(4)*{{.*}})