Created attachment 137352 [details]
Simple EGL/GLES test-case that demonstrates the leak

Compiling a trivial shader will leak glsl_type instances. The following minimal test-case demonstrates the issue when run with valgrind. The output of the incremental leak check should be empty, but it isn't. Alternatively, if you remove the valgrind bits and call the createAndDeleteShader() function in an endless loop, you can observe the memory usage going up slowly. Below is just an excerpt -- I have attached the complete test case separately.

static const char *shaderSource = "void main(){}";

static void createAndDeleteShader()
{
    GLuint shader = glCreateShader(GL_VERTEX_SHADER);
    if (!shader) {
        fprintf(stderr, "Error creating shader\n");
    }
    glShaderSource(shader, 1, &shaderSource, 0);
    glCompileShader(shader);
    glDeleteShader(shader);
}

int main()
{
    ...
    createAndDeleteShader();

    VALGRIND_DO_LEAK_CHECK;

    createAndDeleteShader();

    fprintf(stderr, "---- Memory leaks:\n");
    VALGRIND_DO_CHANGED_LEAK_CHECK;
    fprintf(stderr, "----\n");
    ...
}

The valgrind trace shows that the glsl_type instances used as key in the various type hashes (array_types, record_types, etc.) in glsl_types.cpp are leaked:

==30791== 61 (+61) bytes in 1 (+1) blocks are possibly lost in loss record 882 of 23,604
==30791==    at 0x4C2FB0F: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==30791==    by 0x8813BAC: ralloc_size (ralloc.c:121)
==30791==    by 0x8813FF4: ralloc_array_size (ralloc.c:208)
==30791==    by 0x8813FF4: ralloc_strdup (ralloc.c:353)
==30791==    by 0x87F63C1: glsl_type::glsl_type(glsl_struct_field const*, unsigned int, glsl_interface_packing, bool, char const*) (glsl_types.cpp:147)
==30791==    by 0x87F82E4: glsl_type::get_interface_instance(glsl_struct_field const*, unsigned int, glsl_interface_packing, bool, char const*) (glsl_types.cpp:1145)
==30791==    by 0x87B9AED: construct_interface_instance (builtin_variables.cpp:352)
==30791==    by 0x87B9AED: generate_varyings (builtin_variables.cpp:1406)
==30791==    by 0x87B9AED: _mesa_glsl_initialize_variables(exec_list*, _mesa_glsl_parse_state*) (builtin_variables.cpp:1436)
==30791==    by 0x8782BEB: _mesa_ast_to_hir(exec_list*, _mesa_glsl_parse_state*) (ast_to_hir.cpp:127)
==30791==    by 0x87E8C46: _mesa_glsl_compile_shader (glsl_parser_extras.cpp:2103)
==30791==    by 0x865728F: _mesa_compile_shader (shaderapi.c:1128)
==30791==    by 0x108D8B: createAndDeleteShader (in /home/simon/gltest/gltest)
==30791==    by 0x108FA5: main (in /home/simon/gltest/gltest)
==30791== 
==30791== 408 (+408) bytes in 1 (+1) blocks are possibly lost in loss record 23,047 of 23,604
==30791==    at 0x4C2FB0F: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==30791==    by 0x8813BAC: ralloc_size (ralloc.c:121)
==30791==    by 0x8813C88: rzalloc_size (ralloc.c:153)
==30791==    by 0x87F63D9: glsl_type::glsl_type(glsl_struct_field const*, unsigned int, glsl_interface_packing, bool, char const*) (glsl_types.cpp:148)
==30791==    by 0x87F82E4: glsl_type::get_interface_instance(glsl_struct_field const*, unsigned int, glsl_interface_packing, bool, char const*) (glsl_types.cpp:1145)
==30791==    by 0x87B9AED: construct_interface_instance (builtin_variables.cpp:352)
==30791==    by 0x87B9AED: generate_varyings (builtin_variables.cpp:1406)
==30791==    by 0x87B9AED: _mesa_glsl_initialize_variables(exec_list*, _mesa_glsl_parse_state*) (builtin_variables.cpp:1436)
==30791==    by 0x8782BEB: _mesa_ast_to_hir(exec_list*, _mesa_glsl_parse_state*) (ast_to_hir.cpp:127)
==30791==    by 0x87E8C46: _mesa_glsl_compile_shader (glsl_parser_extras.cpp:2103)
==30791==    by 0x865728F: _mesa_compile_shader (shaderapi.c:1128)
==30791==    by 0x108D8B: createAndDeleteShader (in /home/simon/gltest/gltest)
==30791==    by 0x108FA5: main (in /home/simon/gltest/gltest)
==30791== 
==30791== 571 (+571) bytes in 9 (+9) blocks are possibly lost in loss record 23,191 of 23,604
==30791==    at 0x4C2FB0F: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==30791==    by 0x8813BAC: ralloc_size (ralloc.c:121)
==30791==    by 0x8813FF4: ralloc_array_size (ralloc.c:208)
==30791==    by 0x8813FF4: ralloc_strdup (ralloc.c:353)
==30791==    by 0x87F6428: glsl_type::glsl_type(glsl_struct_field const*, unsigned int, glsl_interface_packing, bool, char const*) (glsl_types.cpp:152)
==30791==    by 0x87F82E4: glsl_type::get_interface_instance(glsl_struct_field const*, unsigned int, glsl_interface_packing, bool, char const*) (glsl_types.cpp:1145)
==30791==    by 0x87B9AED: construct_interface_instance (builtin_variables.cpp:352)
==30791==    by 0x87B9AED: generate_varyings (builtin_variables.cpp:1406)
==30791==    by 0x87B9AED: _mesa_glsl_initialize_variables(exec_list*, _mesa_glsl_parse_state*) (builtin_variables.cpp:1436)
==30791==    by 0x8782BEB: _mesa_ast_to_hir(exec_list*, _mesa_glsl_parse_state*) (ast_to_hir.cpp:127)
==30791==    by 0x87E8C46: _mesa_glsl_compile_shader (glsl_parser_extras.cpp:2103)
==30791==    by 0x865728F: _mesa_compile_shader (shaderapi.c:1128)
==30791==    by 0x108D8B: createAndDeleteShader (in /home/simon/gltest/gltest)
==30791==    by 0x108FA5: main (in /home/simon/gltest/gltest)

Those instances are allocated on the global mem_ctx ralloc context and are therefore "leaking".