diff --git a/libs/vkd3d-shader/hlsl_codegen.c b/libs/vkd3d-shader/hlsl_codegen.c
index fa5a9c1f..37e99a25 100644
--- a/libs/vkd3d-shader/hlsl_codegen.c
+++ b/libs/vkd3d-shader/hlsl_codegen.c
@@ -5253,7 +5253,7 @@ enum vkd3d_shader_interpolation_mode sm4_get_interpolation_mode(struct hlsl_type
 }
 
 static void allocate_semantic_register(struct hlsl_ctx *ctx, struct hlsl_ir_var *var,
-        struct register_allocator *allocator, bool output, bool is_patch_constant_func)
+        struct register_allocator *allocator, bool output, bool optimize, bool is_patch_constant_func)
 {
     static const char *const shader_names[] =
     {
@@ -5312,6 +5312,13 @@ static void allocate_semantic_register(struct hlsl_ctx *ctx, struct hlsl_ir_var
 
         if ((builtin = sm4_register_from_semantic_name(&version, var->semantic.name, output, &type, &has_idx)))
             reg = has_idx ? var->semantic.index : 0;
+
+        if (semantic == VKD3D_SHADER_SV_TESS_FACTOR_TRIINT)
+        {
+            /* While SV_InsideTessFactor can be declared as 'float' for "tri"
+             * domains, it is allocated as if it was 'float[1]'. */
+            var->force_align = true;
+        }
     }
 
     if (builtin)
@@ -5323,18 +5330,21 @@ static void allocate_semantic_register(struct hlsl_ctx *ctx, struct hlsl_ir_var
     {
         int mode = (ctx->profile->major_version < 4)
                 ? 0 : sm4_get_interpolation_mode(var->data_type, var->storage_modifiers);
+        unsigned int reg_size = optimize ? var->data_type->dimx : 4;
 
         var->regs[HLSL_REGSET_NUMERIC] = allocate_register(ctx, allocator, 1,
-                UINT_MAX, 4, var->data_type->dimx, mode, var->force_align);
+                UINT_MAX, reg_size, var->data_type->dimx, mode, var->force_align);
 
-        TRACE("Allocated %s to %s.\n", var->name, debug_register(output ? 'o' : 'v',
-                var->regs[HLSL_REGSET_NUMERIC], var->data_type));
+        TRACE("Allocated %s to %s (mode %d).\n", var->name, debug_register(output ? 'o' : 'v',
+                var->regs[HLSL_REGSET_NUMERIC], var->data_type), mode);
     }
 }
 
 static void allocate_semantic_registers(struct hlsl_ctx *ctx, struct hlsl_ir_function_decl *entry_func)
 {
     struct register_allocator input_allocator = {0}, output_allocator = {0};
+    bool is_vertex_shader = ctx->profile->type == VKD3D_SHADER_TYPE_VERTEX;
+    bool is_pixel_shader = ctx->profile->type == VKD3D_SHADER_TYPE_PIXEL;
     bool is_patch_constant_func = entry_func == ctx->patch_constant_func;
     struct hlsl_ir_var *var;
 
@@ -5344,9 +5354,9 @@ static void allocate_semantic_registers(struct hlsl_ctx *ctx, struct hlsl_ir_fun
     LIST_FOR_EACH_ENTRY(var, &entry_func->extern_vars, struct hlsl_ir_var, extern_entry)
     {
         if (var->is_input_semantic)
-            allocate_semantic_register(ctx, var, &input_allocator, false, is_patch_constant_func);
+            allocate_semantic_register(ctx, var, &input_allocator, false, !is_vertex_shader, is_patch_constant_func);
         if (var->is_output_semantic)
-            allocate_semantic_register(ctx, var, &output_allocator, true, is_patch_constant_func);
+            allocate_semantic_register(ctx, var, &output_allocator, true, !is_pixel_shader, is_patch_constant_func);
     }
 
     vkd3d_free(input_allocator.allocations);
diff --git a/tests/hlsl/interface-packing.shader_test b/tests/hlsl/interface-packing.shader_test
index 9a4dc10c..a9df0893 100644
--- a/tests/hlsl/interface-packing.shader_test
+++ b/tests/hlsl/interface-packing.shader_test
@@ -115,15 +115,15 @@ float4 main(data input) : SV_Target
 
 [test]
 draw triangle list 3
-     probe (0, 0) rgba ( 0.0,  0.0,  0.0,  0.0)
-todo probe (1, 0) rgba ( 1.0, 12.0, 13.0, 14.0)
-todo probe (2, 0) rgba ( 2.0, 15.0, 16.0, 22.0)
-todo probe (3, 0) rgba ( 3.0,  4.0,  5.0, 26.0)
-todo probe (4, 0) rgba ( 6.0, 17.0, 20.0, 21.0)
-todo probe (5, 0) rgba ( 7.0, 18.0, 19.0,  0.0)
-todo probe (6, 0) rgba (27.0, 28.0,  0.0,  0.0)
-todo probe (7, 0) rgba ( 8.0,  9.0, 10.0, 11.0)
-todo probe (8, 0) rgba (23.0, 24.0, 25.0,  0.0)
+probe (0, 0) rgba ( 0.0,  0.0,  0.0,  0.0)
+probe (1, 0) rgba ( 1.0, 12.0, 13.0, 14.0)
+probe (2, 0) rgba ( 2.0, 15.0, 16.0, 22.0)
+probe (3, 0) rgba ( 3.0,  4.0,  5.0, 26.0)
+probe (4, 0) rgba ( 6.0, 17.0, 20.0, 21.0)
+probe (5, 0) rgba ( 7.0, 18.0, 19.0,  0.0)
+probe (6, 0) rgba (27.0, 28.0,  0.0,  0.0)
+probe (7, 0) rgba ( 8.0,  9.0, 10.0, 11.0)
+probe (8, 0) rgba (23.0, 24.0, 25.0,  0.0)
 
 [require]
 shader model >= 3.0