vcc assumes push constants are structs

[btipling]

VVL ERROR: Validation vkCreateShadersEXT(): pCreateInfos[0].pCode (spirv-val produced an error):
PushConstant OpVariable <id> '28[%28]' has illegal type.
From Vulkan spec, Push Constant Interface section:
Such variables must be typed as OpTypeStruct
  %t = OpVariable %_ptr_PushConstant_float PushConstant
The Vulkan spec states: Any variable in the PushConstant Storage Class must be typed as OpTypeStruct (https://vulkan.lunarg.com/doc/view/1.4.313.2/windows/antora/spec/latest/appendices/spirvenv.html#VUID-StandaloneSpirv-PushConstant-06808)

#include <shady.h>
#include <stdint.h>

float floorf(float) __asm__("shady::prim_op::floor");
float fmodf(float, float) __asm__("shady::prim_op::mod");
float sinf(float) __asm__("shady::prim_op::sin");

location(0) output native_vec4 out_color;

push_constant float t;

// A naive triangle
vertex_shader void main()
{
    float pi = 3.1415926535897932385f;
    native_vec4 pos;
    int i = 0;
    switch (gl_VertexIndex) {
        case 0:
            {
                pos = (native_vec4){-0.5f, 0.5f, 0.f, 1.f};
                out_color = (native_vec4){1.f, 0.f, 0.f, 1.f};
                break;
            }
        case 1:
            {
                pos = (native_vec4){0.f, -0.5f, 0.f, 1.f};
                out_color = (native_vec4){0.f, 1.f, 0.f, 1.f};
                break;
            }
        case 2:
            {
                pos = (native_vec4){0.5f, 0.5f, 0.f, 1.f};
                out_color = (native_vec4){0.f, 0.f, 1.f, 1.f};
                break;
            }
        default:
            {
                // Garbage data detectable with Renderdoc
                pos = (native_vec4){7.77f, 7.77f, 7.77f, 7.77f};
                out_color = (native_vec4){1.f, 0.f, 1.f, 1.f};
                break;
            }
    }
    float x_move_interval_ms = 10000.0f;
    float ms = floorf(t * 1000.f);
    float x_pos_modifier = ((fmodf(ms, x_move_interval_ms)) / x_move_interval_ms) * 2.f * (float)pi;
    float s_x_pos_mod = sinf(x_pos_modifier);
    pos.x *= (s_x_pos_mod/2.f);

    gl_Position = pos;
}

if I use a struct I do not get a VVL

#include <shady.h>
#include <stdint.h>

float floorf(float) __asm__("shady::prim_op::floor");
float fmodf(float, float) __asm__("shady::prim_op::mod");
float sinf(float) __asm__("shady::prim_op::sin");

location(0) output native_vec4 out_color;

typedef struct {
    float t;
} pc_t;

push_constant pc_t pc;

// A naive triangle
vertex_shader void main()
{
    float pi = 3.1415926535897932385f;
    native_vec4 pos;
    int i = 0;
    switch (gl_VertexIndex) {
        case 0:
            {
                pos = (native_vec4){-0.5f, 0.5f, 0.f, 1.f};
                out_color = (native_vec4){1.f, 0.f, 0.f, 1.f};
                break;
            }
        case 1:
            {
                pos = (native_vec4){0.f, -0.5f, 0.f, 1.f};
                out_color = (native_vec4){0.f, 1.f, 0.f, 1.f};
                break;
            }
        case 2:
            {
                pos = (native_vec4){0.5f, 0.5f, 0.f, 1.f};
                out_color = (native_vec4){0.f, 0.f, 1.f, 1.f};
                break;
            }
        default:
            {
                // Garbage data detectable with Renderdoc
                pos = (native_vec4){7.77f, 7.77f, 7.77f, 7.77f};
                out_color = (native_vec4){1.f, 0.f, 1.f, 1.f};
                break;
            }
    }
    float x_move_interval_ms = 10000.0f;
    float ms = floorf(pc.t * 1000.f);
    float x_pos_modifier = ((fmodf(ms, x_move_interval_ms)) / x_move_interval_ms) * 2.f * (float)pi;
    float s_x_pos_mod = sinf(x_pos_modifier);
    pos.x *= (s_x_pos_mod/2.f);

    gl_Position = pos;
}

VVLs continue to cause Access Violations that end my program when trying to create the shader, both in the SO and graphics pipeline path.

The slang version of this shader has no problems with the float push constant.

[btipling]

it's kind of cool how I don't have to change the application side code at all from float, I just had to define a struct in the shader and it works just the same. Even cooler is how I can just import the header with the struct into both the application c and the shader see and now they have the same push constant definition.

[Hugobros3]

This is a (Vulkan Appendix A) SPIR-V rule actually:

15.8.1. Push Constant Interface
The shader variables defined with a storage class of PushConstant that are statically used by the
shader entry points for the pipeline define the push constant interface. They must be:
• typed as OpTypeStruct,
• identified with a Block decoration, and
• laid out explicitly using the Offset, ArrayStride, and MatrixStride decorations as specified in
Offset and Stride Assignment.

There are similar requirements for uniform blocks and bindful buffers. Shady needs a normalization pass to enforce these rules, it should be as simple as wrapping all relevant global variables in a struct with the ShdStructFlagBlock | ShdStructFlagExplicitLayout flags set.

[btipling]

Oh I see, I didn't bother to check what slang's spirv-dis output was, it also has an OpTypeStruct

%cbuffer_float_t = OpTypeStruct %float
%_ptr_PushConstant_cbuffer_float_t = OpTypePointer PushConstant %cbuffer_float_t
%_ptr_PushConstant_float = OpTypePointer PushConstant %float
...
%gl_VertexIndex = OpVariable %_ptr_Input_int Input
          %t = OpVariable %_ptr_PushConstant_cbuffer_float_t PushConstant
...
         %58 = OpAccessChain %_ptr_PushConstant_float %t %int_0
         %59 = OpLoad %float %58
         %60 = OpFMul %float %59 %float_1000

ok thank you for explaining

[btipling]

When I use a struct I do still see another VVL:

typedef struct {
    float t;
} pc_t;

push_constant pc_t pc;

From Vulkan spec:
Such variables must be identified with a Block decoration
  %_struct_31 = OpTypeStruct %float
The Vulkan spec states: Any variable in the PushConstant or StorageBuffer storage class must be decorated as Block (https://vulkan.lunarg.com/doc/view/1.4.313.2/windows/antora/spec/latest/appendices/spirvenv.html#VUID-StandaloneSpirv-PushConstant-06675)
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