From 2d848b5bc0b28699f734259f82b48f33d4f6fab1 Mon Sep 17 00:00:00 2001
From: Giovanni Mascellani <gmascellani@codeweavers.com>
Date: Wed, 16 Jul 2025 21:58:36 +0200
Subject: [PATCH] vkd3d-shader/ir: Introduce an abstraction to iterate through
 vsir instructions.

---
 libs/vkd3d-shader/ir.c                   | 11 ++++---
 libs/vkd3d-shader/vkd3d_shader_private.h | 37 ++++++++++++++++++++++++
 2 files changed, 44 insertions(+), 4 deletions(-)

diff --git a/libs/vkd3d-shader/ir.c b/libs/vkd3d-shader/ir.c
index b060ccbb2..9ceb81f2c 100644
--- a/libs/vkd3d-shader/ir.c
+++ b/libs/vkd3d-shader/ir.c
@@ -1579,14 +1579,15 @@ static enum vkd3d_result vsir_program_lower_dcl_output(struct vsir_program *prog
 static enum vkd3d_result vsir_program_lower_instructions(struct vsir_program *program,
         struct vsir_transformation_context *ctx)
 {
-    struct vkd3d_shader_instruction_array *instructions = &program->instructions;
+    struct vsir_program_iterator it = vsir_program_iterator(&program->instructions);
     struct vkd3d_shader_message_context *message_context = ctx->message_context;
-    unsigned int tmp_idx = ~0u, i;
+    struct vkd3d_shader_instruction *ins;
+    unsigned int tmp_idx = ~0u;
     enum vkd3d_result ret;
 
-    for (i = 0; i < instructions->count; ++i)
+    for (ins = vsir_program_iterator_head(&it); ins; ins = vsir_program_iterator_next(&it))
     {
-        struct vkd3d_shader_instruction *ins = &instructions->elements[i];
+        size_t idx = it.idx;
 
         switch (ins->opcode)
         {
@@ -1704,6 +1705,8 @@ static enum vkd3d_result vsir_program_lower_instructions(struct vsir_program *pr
             default:
                 break;
         }
+
+        it.idx = idx;
     }
 
     return VKD3D_OK;
diff --git a/libs/vkd3d-shader/vkd3d_shader_private.h b/libs/vkd3d-shader/vkd3d_shader_private.h
index 4fd16df89..347fd51fe 100644
--- a/libs/vkd3d-shader/vkd3d_shader_private.h
+++ b/libs/vkd3d-shader/vkd3d_shader_private.h
@@ -1419,6 +1419,43 @@ bool shader_instruction_array_clone_instruction(struct vkd3d_shader_instruction_
         unsigned int dst, unsigned int src);
 void shader_instruction_array_destroy(struct vkd3d_shader_instruction_array *instructions);
 
+struct vsir_program_iterator
+{
+    struct vkd3d_shader_instruction_array *array;
+    size_t idx;
+};
+
+static inline struct vsir_program_iterator vsir_program_iterator(struct vkd3d_shader_instruction_array *array)
+{
+    return (struct vsir_program_iterator){ .array = array };
+}
+
+static inline struct vkd3d_shader_instruction *vsir_program_iterator_current(
+        struct vsir_program_iterator *iterator)
+{
+    if (iterator->idx >= iterator->array->count)
+        return NULL;
+
+    return &iterator->array->elements[iterator->idx];
+}
+
+static inline struct vkd3d_shader_instruction *vsir_program_iterator_head(
+        struct vsir_program_iterator *iterator)
+{
+    iterator->idx = 0;
+
+    return vsir_program_iterator_current(iterator);
+}
+
+static inline struct vkd3d_shader_instruction *vsir_program_iterator_next(
+        struct vsir_program_iterator *iterator)
+{
+    if (iterator->idx < iterator->array->count)
+        ++iterator->idx;
+
+    return vsir_program_iterator_current(iterator);
+}
+
 enum vkd3d_shader_config_flags
 {
     VKD3D_SHADER_CONFIG_FLAG_FORCE_VALIDATION = 0x00000001,