Rewrite how IDs are iterated over.

This is a fairly fundamental change on how IDs are handled.
It serves many purposes:

- Improve performance. We only need to iterate over IDs which are
  relevant at any one time.
- Makes sure we iterate through IDs in SPIR-V module declaration order
  rather than ID space. IDs don't have to be monotonically increasing,
  which was an assumption SPIRV-Cross used to have. It has apparently
  never been a problem until now.
- Support LUTs of structs. We do this by interleaving declaration of
  constants and struct types in SPIR-V module order.

To support this, the ParsedIR interface needed to change slightly.
Before setting any ID with variant_set<T> we let ParsedIR know
that an ID with a specific type has been added. The surface for change
should be minimal.

ParsedIR will maintain a per-type list of IDs which the cross-compiler
will need to consider for later.

Instead of looping over ir.ids[] (which can be extremely large), we loop
over types now, using:

ir.for_each_typed_id<SPIRVariable>([&](uint32_t id, SPIRVariable &var) {
	handle_variable(var);
});

Now we make sure that we're never looking at irrelevant types.

2 files changed, 14 insertions, 12 deletions

diff --git a/reference/opt/shaders/vulkan/comp/spec-constant-op-member-array.vk.comp b/reference/opt/shaders/vulkan/comp/spec-constant-op-member-array.vk.comp
index 9344a7a2..33647a42 100644
--- a/reference/opt/shaders/vulkan/comp/spec-constant-op-member-array.vk.comp
+++ b/reference/opt/shaders/vulkan/comp/spec-constant-op-member-array.vk.comp
@@ -9,15 +9,6 @@ const int a = SPIRV_CROSS_CONSTANT_ID_0;
 #define SPIRV_CROSS_CONSTANT_ID_1 200
 #endif
 const int b = SPIRV_CROSS_CONSTANT_ID_1;
-#ifndef SPIRV_CROSS_CONSTANT_ID_2
-#define SPIRV_CROSS_CONSTANT_ID_2 300
-#endif
-const int c = SPIRV_CROSS_CONSTANT_ID_2;
-const int _18 = (c + 50);
-#ifndef SPIRV_CROSS_CONSTANT_ID_3
-#define SPIRV_CROSS_CONSTANT_ID_3 400
-#endif
-const int e = SPIRV_CROSS_CONSTANT_ID_3;
 
 struct A
 {
@@ -31,6 +22,16 @@ struct B
     int member1[a];
 };
 
+#ifndef SPIRV_CROSS_CONSTANT_ID_2
+#define SPIRV_CROSS_CONSTANT_ID_2 300
+#endif
+const int c = SPIRV_CROSS_CONSTANT_ID_2;
+const int _18 = (c + 50);
+#ifndef SPIRV_CROSS_CONSTANT_ID_3
+#define SPIRV_CROSS_CONSTANT_ID_3 400
+#endif
+const int e = SPIRV_CROSS_CONSTANT_ID_3;
+
 layout(binding = 0, std430) buffer SSBO
 {
     A member_a;
diff --git a/reference/opt/shaders/vulkan/comp/spec-constant-op-member-array.vk.comp.vk b/reference/opt/shaders/vulkan/comp/spec-constant-op-member-array.vk.comp.vk
index d9a2822f..cd68e93d 100644
--- a/reference/opt/shaders/vulkan/comp/spec-constant-op-member-array.vk.comp.vk
+++ b/reference/opt/shaders/vulkan/comp/spec-constant-op-member-array.vk.comp.vk
@@ -3,9 +3,6 @@ layout(local_size_x = 1, local_size_y = 1, local_size_z = 1) in;
 
 layout(constant_id = 0) const int a = 100;
 layout(constant_id = 1) const int b = 200;
-layout(constant_id = 2) const int c = 300;
-const int _18 = (c + 50);
-layout(constant_id = 3) const int e = 400;
 
 struct A
 {
@@ -19,6 +16,10 @@ struct B
     int member1[a];
 };
 
+layout(constant_id = 2) const int c = 300;
+const int _18 = (c + 50);
+layout(constant_id = 3) const int e = 400;
+
 layout(set = 1, binding = 0, std430) buffer SSBO
 {
     A member_a;