Am 21.05.2018 um 19:21 schrieb Ian Romanick:
> On 05/10/2018 02:05 AM, Benedikt Schemmer wrote:
>> remove a memset too and yes, this is all functionally identical
>>
>> ---
>> src/mesa/main/shaderapi.c | 40 ++++++++++++++++++++--------------------
>> 1 file changed, 20 insertions(+), 20 deletions(-)
>>
>> diff --git a/src/mesa/main/shaderapi.c b/src/mesa/main/shaderapi.c
>> index e8acca4490..1d0ca5374b 100644
>> --- a/src/mesa/main/shaderapi.c
>> +++ b/src/mesa/main/shaderapi.c
>> @@ -241,11 +241,10 @@ _mesa_init_shader_state(struct gl_context *ctx)
>> /* Device drivers may override these to control what kind of instructions
>> * are generated by the GLSL compiler.
>> */
>> - struct gl_shader_compiler_options options;
>> + struct gl_shader_compiler_options options = {};
>> gl_shader_stage sh;
>> int i;
>>
>> - memset(&options, 0, sizeof(options));
>
> This is not functionally the same. The memset will zero padding fields
> added by the compiler, but '= {}' does not.
I did check with
https://godbolt.org/
and at least for clang (which generates a memset for {}) and gcc it is exactly
the same
void test(void) {
struct gl_shader_compiler_options options = {};
memset(&options, 0, sizeof(options));
}
gcc:
// = {}
mov QWORD PTR [rbp-32], 0
mov QWORD PTR [rbp-24], 0
mov QWORD PTR [rbp-16], 0
// memset
lea rax, [rbp-32]
mov edx, 24
mov esi, 0
mov rdi, rax
call memset
clang:
// = {}
mov rdi, rsi
mov qword ptr [rbp - 32], rsi # 8-byte Spill
mov esi, eax
mov qword ptr [rbp - 40], rdx # 8-byte Spill
mov dword ptr [rbp - 44], eax # 4-byte Spill
call memset
//memset
mov rdx, qword ptr [rbp - 32] # 8-byte Reload
mov rdi, rdx
mov esi, dword ptr [rbp - 44] # 4-byte Reload
mov rdx, qword ptr [rbp - 40] # 8-byte Reload
call memset
but your right intel compilers generate something weird:
// = {}
lea rax, QWORD PTR [-32+rbp] #71.47
mov edx, 0 #71.47
mov ecx, 24 #71.47
mov rdi, rax #71.47
mov eax, edx #71.47
and eax, 65535 #71.47
mov ah, al #71.47
mov edx, eax #71.47
shl eax, 16 #71.47
or eax, edx #71.47
mov esi, ecx #71.47
shr rcx, 2 #71.47
rep stosd #71.47
mov ecx, esi #71.47
and ecx, 3 #71.47
rep stosb #71.47
// memset
lea rax, QWORD PTR [-32+rbp] #72.5
mov edx, 0 #72.5
mov ecx, 24 #72.5
mov rdi, rax #72.5
mov esi, edx #72.5
mov rdx, rcx #72.5
call memset #72.5
mov QWORD PTR [-8+rbp], rax #72.5
>
> I'm also not fond of the The '!= 0' and '== NULL' changes. Pretty much
> everywhere in core Mesa uses those patterns.>
> I feel like most of this is just a bunch of spurious changes that will
> just make cherry picking patches to stable irritating later on.
>
>> options.MaxUnrollIterations = 32;
>> options.MaxIfDepth = UINT_MAX;
>>
>> @@ -254,7 +253,7 @@ _mesa_init_shader_state(struct gl_context *ctx)
>>
>> ctx->Shader.Flags = _mesa_get_shader_flags();
>>
>> - if (ctx->Shader.Flags != 0)
>> + if (ctx->Shader.Flags)
>> ctx->Const.GenerateTemporaryNames = true;
>>
>> /* Extended for ARB_separate_shader_objects */
>> @@ -771,7 +770,8 @@ get_programiv(struct gl_context *ctx, GLuint program,
>> GLenum pname,
>> GLint *params)
>> {
>> struct gl_shader_program *shProg
>> - = _mesa_lookup_shader_program_err(ctx, program,
>> "glGetProgramiv(program)");
>> + = _mesa_lookup_shader_program_err(ctx, program,
>> + "glGetProgramiv(program)");
>>
>> /* Is transform feedback available in this context?
>> */
>> @@ -953,7 +953,7 @@ get_programiv(struct gl_context *ctx, GLuint program,
>> GLenum pname,
>> *params = shProg->BinaryRetreivableHint;
>> return;
>> case GL_PROGRAM_BINARY_LENGTH:
>> - if (ctx->Const.NumProgramBinaryFormats == 0) {
>> + if (!ctx->Const.NumProgramBinaryFormats) {
>> *params = 0;
>> } else {
>> _mesa_get_program_binary_length(ctx, shProg, params);
>> @@ -974,7 +974,7 @@ get_programiv(struct gl_context *ctx, GLuint program,
>> GLenum pname,
>> "linked)");
>> return;
>> }
>> - if (shProg->_LinkedShaders[MESA_SHADER_COMPUTE] == NULL) {
>> + if (!shProg->_LinkedShaders[MESA_SHADER_COMPUTE]) {
>> _mesa_error(ctx, GL_INVALID_OPERATION, "glGetProgramiv(no compute "
>> "shaders)");
>> return;
>> @@ -1234,7 +1234,7 @@ _mesa_compile_shader(struct gl_context *ctx, struct
>> gl_shader *sh)
>> } else {
>> if (ctx->_Shader->Flags & GLSL_DUMP) {
>> _mesa_log("GLSL source for %s shader %d:\n",
>> - _mesa_shader_stage_to_string(sh->Stage), sh->Name);
>> + _mesa_shader_stage_to_string(sh->Stage), sh->Name);
>> _mesa_log("%s\n", sh->Source);
>> }
>>
>> @@ -1381,13 +1381,13 @@ link_program(struct gl_context *ctx, struct
>> gl_shader_program *shProg,
>> GLuint i;
>>
>> printf("Link %u shaders in program %u: %s\n",
>> - shProg->NumShaders, shProg->Name,
>> - shProg->data->LinkStatus ? "Success" : "Failed");
>> + shProg->NumShaders, shProg->Name,
>> + shProg->data->LinkStatus ? "Success" : "Failed");
>>
>> for (i = 0; i < shProg->NumShaders; i++) {
>> printf(" shader %u, stage %u\n",
>> - shProg->Shaders[i]->Name,
>> - shProg->Shaders[i]->Stage);
>> + shProg->Shaders[i]->Name,
>> + shProg->Shaders[i]->Stage);
>> }
>> }
>> }
>> @@ -1460,7 +1460,7 @@ void
>> _mesa_active_program(struct gl_context *ctx, struct gl_shader_program
>> *shProg,
>> const char *caller)
>> {
>> - if ((shProg != NULL) && !shProg->data->LinkStatus) {
>> + if ((shProg) && !shProg->data->LinkStatus) {
>> _mesa_error(ctx, GL_INVALID_OPERATION,
>> "%s(program %u not linked)", caller, shProg->Name);
>> return;
>> @@ -1794,7 +1794,7 @@ void GLAPIENTRY
>> _mesa_GetObjectParameterfvARB(GLhandleARB object, GLenum pname,
>> GLfloat *params)
>> {
>> - GLint iparams[1] = {0}; /* XXX is one element enough? */
>> + GLint iparams[1] = {}; /* XXX is one element enough? */
>> _mesa_GetObjectParameterivARB(object, pname, iparams);
>> params[0] = (GLfloat) iparams[0];
>> }
>> @@ -1912,7 +1912,7 @@ shader_source(struct gl_context *ctx, GLuint
>> shaderObj, GLsizei count,
>> if (!sh)
>> return;
>>
>> - if (string == NULL) {
>> + if (!string) {
>> _mesa_error(ctx, GL_INVALID_VALUE, "glShaderSourceARB");
>> return;
>> }
>> @@ -1925,7 +1925,7 @@ shader_source(struct gl_context *ctx, GLuint
>> shaderObj, GLsizei count,
>> * last element will be set to the total length of the source code.
>> */
>> offsets = malloc(count * sizeof(GLint));
>> - if (offsets == NULL) {
>> + if (!offsets) {
>> _mesa_error(ctx, GL_OUT_OF_MEMORY, "glShaderSourceARB");
>> return;
>> }
>> @@ -1952,7 +1952,7 @@ shader_source(struct gl_context *ctx, GLuint
>> shaderObj, GLsizei count,
>> */
>> totalLength = offsets[count - 1] + 2;
>> source = malloc(totalLength * sizeof(GLcharARB));
>> - if (source == NULL) {
>> + if (!source) {
>> free((GLvoid *) offsets);
>> _mesa_error(ctx, GL_OUT_OF_MEMORY, "glShaderSourceARB");
>> return;
>> @@ -2245,7 +2245,7 @@ _mesa_GetProgramBinary(GLuint program, GLsizei
>> bufSize, GLsizei *length,
>> * Ensure that length always points to valid storage to avoid multiple
>> NULL
>> * pointer checks below.
>> */
>> - if (length == NULL)
>> + if (!length)
>> length = &length_dummy;
>>
>>
>> @@ -2263,7 +2263,7 @@ _mesa_GetProgramBinary(GLuint program, GLsizei
>> bufSize, GLsizei *length,
>> return;
>> }
>>
>> - if (ctx->Const.NumProgramBinaryFormats == 0) {
>> + if (!ctx->Const.NumProgramBinaryFormats) {
>> *length = 0;
>> _mesa_error(ctx, GL_INVALID_OPERATION,
>> "glGetProgramBinary(driver supports zero binary
>> formats)");
>> @@ -2858,7 +2858,7 @@ _mesa_UniformSubroutinesuiv(GLenum shadertype, GLsizei
>> count,
>> bool flushed = false;
>> do {
>> struct gl_uniform_storage *uni = p->sh.SubroutineUniformRemapTable[i];
>> - if (uni == NULL) {
>> + if (!uni) {
>> i++;
>> continue;
>> }
>> @@ -3054,7 +3054,7 @@ _mesa_shader_write_subroutine_index(struct gl_context
>> *ctx,
>> {
>> int i, j;
>>
>> - if (p->sh.NumSubroutineUniformRemapTable == 0)
>> + if (!p->sh.NumSubroutineUniformRemapTable)
>> return;
>>
>> i = 0;
>>
>
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