diff --git a/dlls/d3dcompiler_43/d3dcompiler_private.h b/dlls/d3dcompiler_43/d3dcompiler_private.h
index de948fab8a0..a6c27d0e10d 100644
--- a/dlls/d3dcompiler_43/d3dcompiler_private.h
+++ b/dlls/d3dcompiler_43/d3dcompiler_private.h
@@ -752,10 +752,19 @@ struct hlsl_ir_var
     struct hlsl_var_allocation *allocation;
 };
 
+struct hlsl_ir_function
+{
+    struct wine_rb_entry entry;
+    const char *name;
+    struct wine_rb_tree overloads;
+    BOOL intrinsic;
+};
+
 struct hlsl_ir_function_decl
 {
     struct hlsl_ir_node node;
-    const char *name;
+    struct wine_rb_entry entry;
+    struct hlsl_ir_function *func;
     const char *semantic;
     struct list *parameters;
     struct list *body;
@@ -960,6 +969,12 @@ struct parse_variable_def
     struct list *initializer;
 };
 
+struct parse_function
+{
+    char *name;
+    struct hlsl_ir_function_decl *decl;
+};
+
 struct parse_if_body
 {
     struct list *then_instrs;
@@ -1004,7 +1019,7 @@ struct hlsl_parse_ctx
     struct list scopes;
 
     struct list types;
-    struct list functions;
+    struct wine_rb_tree functions;
 
     enum hlsl_matrix_majority matrix_majority;
 };
@@ -1127,18 +1142,21 @@ struct hlsl_ir_node *make_assignment(struct hlsl_ir_node *left, enum parse_assig
         DWORD writemask, struct hlsl_ir_node *right) DECLSPEC_HIDDEN;
 void push_scope(struct hlsl_parse_ctx *ctx) DECLSPEC_HIDDEN;
 BOOL pop_scope(struct hlsl_parse_ctx *ctx) DECLSPEC_HIDDEN;
-struct hlsl_ir_function_decl *new_func_decl(const char *name, struct hlsl_type *return_type, struct list *parameters) DECLSPEC_HIDDEN;
+struct hlsl_ir_function_decl *new_func_decl(struct hlsl_type *return_type, struct list *parameters) DECLSPEC_HIDDEN;
+void init_functions_tree(struct wine_rb_tree *funcs) DECLSPEC_HIDDEN;
+void add_function_decl(struct wine_rb_tree *funcs, char *name, struct hlsl_ir_function_decl *decl,
+        BOOL intrinsic) DECLSPEC_HIDDEN;
 struct bwriter_shader *parse_hlsl_shader(const char *text, enum shader_type type, DWORD major, DWORD minor,
         const char *entrypoint, char **messages) DECLSPEC_HIDDEN;
 
 const char *debug_hlsl_type(const struct hlsl_type *type) DECLSPEC_HIDDEN;
 const char *debug_modifiers(DWORD modifiers) DECLSPEC_HIDDEN;
-void debug_dump_ir_function(const struct hlsl_ir_function_decl *func) DECLSPEC_HIDDEN;
+void debug_dump_ir_function_decl(const struct hlsl_ir_function_decl *func) DECLSPEC_HIDDEN;
 
 void free_hlsl_type(struct hlsl_type *type) DECLSPEC_HIDDEN;
 void free_instr(struct hlsl_ir_node *node) DECLSPEC_HIDDEN;
 void free_instr_list(struct list *list) DECLSPEC_HIDDEN;
-void free_function(struct hlsl_ir_function_decl *func) DECLSPEC_HIDDEN;
+void free_function_rb(struct wine_rb_entry *entry, void *context) DECLSPEC_HIDDEN;
 
 
 #define MAKE_TAG(ch0, ch1, ch2, ch3) \
diff --git a/dlls/d3dcompiler_43/hlsl.y b/dlls/d3dcompiler_43/hlsl.y
index 738ab3ab7f5..d32710202ef 100644
--- a/dlls/d3dcompiler_43/hlsl.y
+++ b/dlls/d3dcompiler_43/hlsl.y
@@ -825,7 +825,7 @@ static BOOL add_typedef(DWORD modifiers, struct hlsl_type *orig_type, struct lis
     struct hlsl_ir_var *var;
     struct hlsl_ir_node *instr;
     struct list *list;
-    struct hlsl_ir_function_decl *function;
+    struct parse_function function;
     struct parse_parameter parameter;
     struct parse_variable_def *variable_def;
     struct parse_if_body if_body;
@@ -1000,8 +1000,8 @@ hlsl_prog:                /* empty */
                             }
                         | hlsl_prog func_declaration
                             {
-                                FIXME("Check that the function doesn't conflict with an already declared one.\n");
-                                list_add_tail(&hlsl_ctx.functions, &$2->node.entry);
+                                TRACE("Adding function '%s' to the function list.\n", $2.name);
+                                add_function_decl(&hlsl_ctx.functions, $2.name, $2.decl, FALSE);
                             }
                         | hlsl_prog declaration_statement
                             {
@@ -1125,14 +1125,14 @@ field:                    var_modifiers type variables_def ';'
 
 func_declaration:         func_prototype compound_statement
                             {
-                                TRACE("Function %s parsed.\n", $1->name);
+                                TRACE("Function %s parsed.\n", $1.name);
                                 $$ = $1;
-                                $$->body = $2;
+                                $$.decl->body = $2;
                                 pop_scope(&hlsl_ctx);
                             }
                         | func_prototype ';'
                             {
-                                TRACE("Function prototype for %s.\n", $1->name);
+                                TRACE("Function prototype for %s.\n", $1.name);
                                 $$ = $1;
                                 pop_scope(&hlsl_ctx);
                             }
@@ -1151,13 +1151,15 @@ func_prototype:           var_modifiers type var_identifier '(' parameters ')' s
                                             HLSL_LEVEL_ERROR, "void function with a semantic");
                                 }
 
-                                $$ = new_func_decl($3, $2, $5);
-                                if (!$$)
+                                $$.decl = new_func_decl($2, $5);
+                                if (!$$.decl)
                                 {
                                     ERR("Out of memory.\n");
                                     return -1;
                                 }
-                                $$->semantic = $7;
+                                $$.name = $3;
+                                $$.decl->semantic = $7;
+                                set_location(&$$.decl->node.loc, &@3);
                             }
 
 compound_statement:       '{' '}'
@@ -2330,10 +2332,22 @@ static DWORD add_modifier(DWORD modifiers, DWORD mod, const struct YYLTYPE *loc)
     return modifiers | mod;
 }
 
+static void dump_function_decl(struct wine_rb_entry *entry, void *context)
+{
+    struct hlsl_ir_function_decl *func = WINE_RB_ENTRY_VALUE(entry, struct hlsl_ir_function_decl, entry);
+    if (func->body)
+        debug_dump_ir_function_decl(func);
+}
+
+static void dump_function(struct wine_rb_entry *entry, void *context)
+{
+    struct hlsl_ir_function *func = WINE_RB_ENTRY_VALUE(entry, struct hlsl_ir_function, entry);
+    wine_rb_for_each_entry(&func->overloads, dump_function_decl, NULL);
+}
+
 struct bwriter_shader *parse_hlsl(enum shader_type type, DWORD major, DWORD minor,
         const char *entrypoint, char **messages)
 {
-    struct hlsl_ir_function_decl *function, *next_function;
     struct hlsl_scope *scope, *next_scope;
     struct hlsl_type *hlsl_type, *next_type;
     struct hlsl_ir_var *var, *next_var;
@@ -2351,7 +2365,7 @@ struct bwriter_shader *parse_hlsl(enum shader_type type, DWORD major, DWORD mino
     hlsl_ctx.matrix_majority = HLSL_COLUMN_MAJOR;
     list_init(&hlsl_ctx.scopes);
     list_init(&hlsl_ctx.types);
-    list_init(&hlsl_ctx.functions);
+    init_functions_tree(&hlsl_ctx.functions);
 
     push_scope(&hlsl_ctx);
     hlsl_ctx.globals = hlsl_ctx.cur_scope;
@@ -2361,14 +2375,8 @@ struct bwriter_shader *parse_hlsl(enum shader_type type, DWORD major, DWORD mino
 
     if (TRACE_ON(hlsl_parser))
     {
-        struct hlsl_ir_function_decl *func;
-
         TRACE("IR dump.\n");
-        LIST_FOR_EACH_ENTRY(func, &hlsl_ctx.functions, struct hlsl_ir_function_decl, node.entry)
-        {
-            if (func->body)
-                debug_dump_ir_function(func);
-        }
+        wine_rb_for_each_entry(&hlsl_ctx.functions, dump_function, NULL);
     }
 
     TRACE("Compilation status = %d\n", hlsl_ctx.status);
@@ -2390,8 +2398,7 @@ struct bwriter_shader *parse_hlsl(enum shader_type type, DWORD major, DWORD mino
     d3dcompiler_free(hlsl_ctx.source_files);
 
     TRACE("Freeing functions IR.\n");
-    LIST_FOR_EACH_ENTRY_SAFE(function, next_function, &hlsl_ctx.functions, struct hlsl_ir_function_decl, node.entry)
-        free_function(function);
+    wine_rb_destroy(&hlsl_ctx.functions, free_function_rb, NULL);
 
     TRACE("Freeing variables.\n");
     LIST_FOR_EACH_ENTRY_SAFE(scope, next_scope, &hlsl_ctx.scopes, struct hlsl_scope, entry)
diff --git a/dlls/d3dcompiler_43/utils.c b/dlls/d3dcompiler_43/utils.c
index 5bd39e8dec5..e5f3f74503e 100644
--- a/dlls/d3dcompiler_43/utils.c
+++ b/dlls/d3dcompiler_43/utils.c
@@ -878,14 +878,7 @@ struct hlsl_type *get_type(struct hlsl_scope *scope, const char *name, BOOL recu
 
 BOOL find_function(const char *name)
 {
-    struct hlsl_ir_function_decl *func;
-
-    LIST_FOR_EACH_ENTRY(func, &hlsl_ctx.functions, struct hlsl_ir_function_decl, node.entry)
-    {
-        if (!strcmp(func->name, name))
-            return TRUE;
-    }
-    return FALSE;
+    return wine_rb_get(&hlsl_ctx.functions, name) != NULL;
 }
 
 unsigned int components_count_type(struct hlsl_type *type)
@@ -1762,7 +1755,7 @@ BOOL pop_scope(struct hlsl_parse_ctx *ctx)
     return TRUE;
 }
 
-struct hlsl_ir_function_decl *new_func_decl(const char *name, struct hlsl_type *return_type, struct list *parameters)
+struct hlsl_ir_function_decl *new_func_decl(struct hlsl_type *return_type, struct list *parameters)
 {
     struct hlsl_ir_function_decl *decl;
 
@@ -1774,12 +1767,117 @@ struct hlsl_ir_function_decl *new_func_decl(const char *name, struct hlsl_type *
     }
     decl->node.type = HLSL_IR_FUNCTION_DECL;
     decl->node.data_type = return_type;
-    decl->name = name;
     decl->parameters = parameters;
 
     return decl;
 }
 
+static int compare_param_hlsl_types(const struct hlsl_type *t1, const struct hlsl_type *t2)
+{
+    if (t1->type != t2->type)
+    {
+        if (!((t1->type == HLSL_CLASS_SCALAR && t2->type == HLSL_CLASS_VECTOR)
+                || (t1->type == HLSL_CLASS_VECTOR && t2->type == HLSL_CLASS_SCALAR)))
+            return t1->type - t2->type;
+    }
+    if (t1->base_type != t2->base_type)
+        return t1->base_type - t2->base_type;
+    if (t1->base_type == HLSL_TYPE_SAMPLER && t1->sampler_dim != t2->sampler_dim)
+        return t1->sampler_dim - t2->sampler_dim;
+    if (t1->dimx != t2->dimx)
+        return t1->dimx - t2->dimx;
+    if (t1->dimy != t2->dimy)
+        return t1->dimx - t2->dimx;
+    if (t1->type == HLSL_CLASS_STRUCT)
+    {
+        struct list *t1cur, *t2cur;
+        struct hlsl_struct_field *t1field, *t2field;
+        int r;
+
+        t1cur = list_head(t1->e.elements);
+        t2cur = list_head(t2->e.elements);
+        while (t1cur && t2cur)
+        {
+            t1field = LIST_ENTRY(t1cur, struct hlsl_struct_field, entry);
+            t2field = LIST_ENTRY(t2cur, struct hlsl_struct_field, entry);
+            if ((r = compare_param_hlsl_types(t1field->type, t2field->type)))
+                return r;
+            if ((r = strcmp(t1field->name, t2field->name)))
+                return r;
+            t1cur = list_next(t1->e.elements, t1cur);
+            t2cur = list_next(t2->e.elements, t2cur);
+        }
+        if (t1cur != t2cur)
+            return t1cur ? 1 : -1;
+        return 0;
+    }
+    if (t1->type == HLSL_CLASS_ARRAY)
+    {
+        if (t1->e.array.elements_count != t2->e.array.elements_count)
+            return t1->e.array.elements_count - t2->e.array.elements_count;
+        return compare_param_hlsl_types(t1->e.array.type, t2->e.array.type);
+    }
+
+    return 0;
+}
+
+static int compare_function_decl_rb(const void *key, const struct wine_rb_entry *entry)
+{
+    const struct list *params = (const struct list *)key;
+    const struct hlsl_ir_function_decl *decl = WINE_RB_ENTRY_VALUE(entry, const struct hlsl_ir_function_decl, entry);
+    int params_count = params ? list_count(params) : 0;
+    int decl_params_count = decl->parameters ? list_count(decl->parameters) : 0;
+    int r;
+    struct list *p1cur, *p2cur;
+
+    if (params_count != decl_params_count)
+        return params_count - decl_params_count;
+
+    p1cur = params ? list_head(params) : NULL;
+    p2cur = decl->parameters ? list_head(decl->parameters) : NULL;
+    while (p1cur && p2cur)
+    {
+        struct hlsl_ir_var *p1, *p2;
+        p1 = LIST_ENTRY(p1cur, struct hlsl_ir_var, node.entry);
+        p2 = LIST_ENTRY(p2cur, struct hlsl_ir_var, node.entry);
+        if ((r = compare_param_hlsl_types(p1->node.data_type, p2->node.data_type)))
+            return r;
+        p1cur = list_next(params, p1cur);
+        p2cur = list_next(decl->parameters, p2cur);
+    }
+    return 0;
+}
+
+static const struct wine_rb_functions hlsl_ir_function_decl_rb_funcs =
+{
+    d3dcompiler_alloc_rb,
+    d3dcompiler_realloc_rb,
+    d3dcompiler_free_rb,
+    compare_function_decl_rb,
+};
+
+static int compare_function_rb(const void *key, const struct wine_rb_entry *entry)
+{
+    const char *name = (const char *)key;
+    const struct hlsl_ir_function *func = WINE_RB_ENTRY_VALUE(entry, const struct hlsl_ir_function,entry);
+
+    return strcmp(name, func->name);
+}
+
+static const struct wine_rb_functions function_rb_funcs =
+{
+    d3dcompiler_alloc_rb,
+    d3dcompiler_realloc_rb,
+    d3dcompiler_free_rb,
+    compare_function_rb,
+};
+
+void init_functions_tree(struct wine_rb_tree *funcs)
+{
+    if (wine_rb_init(&hlsl_ctx.functions, &function_rb_funcs) == -1)
+        ERR("Failed to initialize functions rbtree.\n");
+}
+
 static const char *debug_base_type(const struct hlsl_type *type)
 {
     const char *name = "(unknown)";
@@ -2198,11 +2296,11 @@ static void debug_dump_instr(const struct hlsl_ir_node *instr)
     }
 }
 
-void debug_dump_ir_function(const struct hlsl_ir_function_decl *func)
+void debug_dump_ir_function_decl(const struct hlsl_ir_function_decl *func)
 {
     struct hlsl_ir_var *param;
 
-    TRACE("Dumping function %s.\n", debugstr_a(func->name));
+    TRACE("Dumping function %s.\n", debugstr_a(func->func->name));
     TRACE("Function parameters:\n");
     LIST_FOR_EACH_ENTRY(param, func->parameters, struct hlsl_ir_var, node.entry)
     {
@@ -2370,11 +2468,69 @@ void free_instr(struct hlsl_ir_node *node)
     }
 }
 
-void free_function(struct hlsl_ir_function_decl *func)
+void free_function_decl(struct hlsl_ir_function_decl *func)
 {
-    d3dcompiler_free((void *)func->name);
     d3dcompiler_free((void *)func->semantic);
     d3dcompiler_free(func->parameters);
     free_instr_list(func->body);
     d3dcompiler_free(func);
 }
+
+static void free_function_decl_rb(struct wine_rb_entry *entry, void *context)
+{
+    free_function_decl(WINE_RB_ENTRY_VALUE(entry, struct hlsl_ir_function_decl, entry));
+}
+
+void free_function(struct hlsl_ir_function *func)
+{
+    wine_rb_destroy(&func->overloads, free_function_decl_rb, NULL);
+    d3dcompiler_free((void *)func->name);
+}
+
+void free_function_rb(struct wine_rb_entry *entry, void *context)
+{
+    free_function(WINE_RB_ENTRY_VALUE(entry, struct hlsl_ir_function, entry));
+}
+
+void add_function_decl(struct wine_rb_tree *funcs, char *name, struct hlsl_ir_function_decl *decl, BOOL intrinsic)
+{
+    struct hlsl_ir_function *func;
+    struct wine_rb_entry *func_entry, *old_entry;
+
+    func_entry = wine_rb_get(funcs, name);
+    if (func_entry)
+    {
+        func = WINE_RB_ENTRY_VALUE(func_entry, struct hlsl_ir_function, entry);
+        decl->func = func;
+        if ((old_entry = wine_rb_get(&func->overloads, decl->parameters)))
+        {
+            struct hlsl_ir_function_decl *old_decl =
+                    WINE_RB_ENTRY_VALUE(old_entry, struct hlsl_ir_function_decl, entry);
+
+            if (!decl->body)
+            {
+                free_function_decl(decl);
+                d3dcompiler_free(name);
+                return;
+            }
+            wine_rb_remove(&func->overloads, decl->parameters);
+            free_function_decl(old_decl);
+        }
+        wine_rb_put(&func->overloads, decl->parameters, &decl->entry);
+        d3dcompiler_free(name);
+        return;
+    }
+    func = d3dcompiler_alloc(sizeof(*func));
+    func->name = name;
+    if (wine_rb_init(&func->overloads, &hlsl_ir_function_decl_rb_funcs) == -1)
+    {
+        ERR("Failed to initialize function rbtree.\n");
+        d3dcompiler_free(name);
+        d3dcompiler_free(func);
+        return;
+    }
+    decl->func = func;
+    wine_rb_put(&func->overloads, decl->parameters, &decl->entry);
+    func->intrinsic = intrinsic;
+    wine_rb_put(funcs, func->name, &func->entry);
+}