GPGPU: Add dummy implementation for ast expression construction

Instead of calling to a pet function that does not return anything, we pass
our own dummy implementation to ppcg that always returns a nullptr. This
ensures that the list of ast expressions always contains a nullptr and we do
not accidentally free a random (uninitalized) pointer. This resolves the
last valgrind warning we see.

We provide an implementation for this function, when the generated AST
expressions can be used and consequently can be tested.

llvm-svn: 275435

3 files changed, 37 insertions, 4 deletions

diff --git a/polly/lib/CodeGen/PPCGCodeGeneration.cpp b/polly/lib/CodeGen/PPCGCodeGeneration.cpp
index d0921db4a7b..bb6ea8cd27e 100644
--- a/polly/lib/CodeGen/PPCGCodeGeneration.cpp
+++ b/polly/lib/CodeGen/PPCGCodeGeneration.cpp
@@ -41,6 +41,23 @@ static cl::opt<bool> DumpSchedule("polly-acc-dump-schedule",
                                   cl::desc("Dump the computed GPU Schedule"),
                                   cl::Hidden, cl::init(false), cl::ZeroOrMore,
                                   cl::cat(PollyCategory));
+/// Create the ast expressions for a ScopStmt.
+///
+/// This function is a callback for to generate the ast expressions for each
+/// of the scheduled ScopStmts.
+static __isl_give isl_id_to_ast_expr *pollyBuildAstExprForStmt(
+    void *Stmt, isl_ast_build *Build,
+    isl_multi_pw_aff *(*FunctionIndex)(__isl_take isl_multi_pw_aff *MPA,
+                                       isl_id *Id, void *User),
+    void *UserIndex,
+    isl_ast_expr *(*FunctionExpr)(isl_ast_expr *Expr, isl_id *Id, void *User),
+    void *User_expr) {
+
+  // TODO: Implement the AST expression generation. For now we just return a
+  // nullptr to ensure that we do not free uninitialized pointers.
+
+  return nullptr;
+}
 
 namespace {
 class PPCGCodeGeneration : public ScopPass {
@@ -288,6 +305,7 @@ public:
     PPCGGen->options = PPCGScop->options;
     PPCGGen->print = nullptr;
     PPCGGen->print_user = nullptr;
+    PPCGGen->build_ast_expr = &pollyBuildAstExprForStmt;
     PPCGGen->prog = PPCGProg;
     PPCGGen->tree = nullptr;
     PPCGGen->types.n = 0;
diff --git a/polly/lib/External/ppcg/gpu.c b/polly/lib/External/ppcg/gpu.c
index 3eecf45656c..7bda56a4648 100644
--- a/polly/lib/External/ppcg/gpu.c
+++ b/polly/lib/External/ppcg/gpu.c
@@ -1453,6 +1453,7 @@ static int find_array_index(struct ppcg_kernel *kernel, const char *name)
  * to the current kernel.
  */
 struct ppcg_transform_data {
+        struct ppcg_options *options;
 	struct ppcg_kernel *kernel;
 	struct gpu_stmt_access *accesses;
 	isl_pw_multi_aff *iterator_map;
@@ -1787,7 +1788,8 @@ static __isl_give isl_ast_expr *transform_expr(__isl_take isl_ast_expr *expr,
  */
 static __isl_give isl_ast_node *create_domain_leaf(
 	struct ppcg_kernel *kernel, __isl_take isl_ast_node *node,
-	__isl_keep isl_ast_build *build, struct gpu_stmt *gpu_stmt)
+	__isl_keep isl_ast_build *build, struct gpu_stmt *gpu_stmt,
+        struct gpu_gen *gen)
 {
 	struct ppcg_transform_data data;
 	struct ppcg_kernel_stmt *stmt;
@@ -1822,10 +1824,9 @@ static __isl_give isl_ast_node *create_domain_leaf(
 	data.accesses = stmt->u.d.stmt->accesses;
 	data.iterator_map = iterator_map;
 	data.sched2shared = sched2shared;
-	stmt->u.d.ref2expr = pet_stmt_build_ast_exprs(stmt->u.d.stmt->stmt,
+	stmt->u.d.ref2expr = gen->build_ast_expr(stmt->u.d.stmt->stmt,
 					    build, &transform_index, &data,
 					    &transform_expr, &data);
-
 	isl_pw_multi_aff_free(iterator_map);
 	isl_pw_multi_aff_free(sched2shared);
 
@@ -1944,6 +1945,7 @@ static __isl_give isl_ast_node *create_sync_leaf(
  */
 struct ppcg_at_domain_data {
 	struct gpu_prog *prog;
+	struct gpu_gen *gen;
 	struct ppcg_kernel *kernel;
 };
 
@@ -1985,7 +1987,8 @@ static __isl_give isl_ast_node *at_domain(__isl_take isl_ast_node *node,
 	isl_id_free(id);
 
 	if (gpu_stmt)
-		return create_domain_leaf(data->kernel, node, build, gpu_stmt);
+		return create_domain_leaf(data->kernel, node, build, gpu_stmt,
+                                          data->gen);
 
 	if (!prefixcmp(name, "to_device_") || !prefixcmp(name, "from_device_"))
 		return node;
@@ -2304,6 +2307,7 @@ static __isl_give isl_ast_node *generate_code(struct gpu_gen *gen,
 	int depth;
 
 	data.prog = gen->prog;
+	data.gen = gen;
 	data.kernel = NULL;
 
 	depth = 0;
diff --git a/polly/lib/External/ppcg/gpu.h b/polly/lib/External/ppcg/gpu.h
index c5009c0b2c2..7038901f1d7 100644
--- a/polly/lib/External/ppcg/gpu.h
+++ b/polly/lib/External/ppcg/gpu.h
@@ -148,6 +148,17 @@ struct gpu_gen {
 		struct gpu_types *types, void *user);
 	void *print_user;
 
+        isl_id_to_ast_expr *(*build_ast_expr)(void *stmt,
+	        isl_ast_build *build,
+        	isl_multi_pw_aff *(*fn_index)(
+	        	__isl_take isl_multi_pw_aff *mpa, isl_id *id,
+		        void *user),
+                void *user_index,
+        	isl_ast_expr *(*fn_expr)(isl_ast_expr *expr,
+		        isl_id *id, void *user),
+        void *user_expr);
+
+
 	struct gpu_prog *prog;
 	/* The generated AST. */
 	isl_ast_node *tree;