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Fix shader timestamp churn on checked-in shaders #1468

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Fix shader timestamp churn on checked-in shaders #1468

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8596646
Optimize shader build system to avoid unnecessary rebuilds and source…
gpx1000 Jan 10, 2026
b555e46
Update copyright year to 2026 in sample_helper.cmake
gpx1000 Jan 10, 2026
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28 changes: 17 additions & 11 deletions bldsys/cmake/sample_helper.cmake
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Original file line number Diff line number Diff line change
@@ -1,7 +1,7 @@
#[[
Copyright (c) 2019-2025, Arm Limited and Contributors
Copyright (c) 2024-2025, Mobica Limited
Copyright (c) 2024-2025, Sascha Willems
Copyright (c) 2019-2026, Arm Limited and Contributors
Copyright (c) 2024-2026, Mobica Limited
Copyright (c) 2024-2026, Sascha Willems

SPDX-License-Identifier: Apache-2.0

Expand Down Expand Up @@ -197,6 +197,7 @@ endif()
endif()

# HLSL compilation via DXC
# Only build HLSL shaders when their sources change. Avoid touching source tree unnecessarily.
if(Vulkan_dxc_EXECUTABLE AND DEFINED SHADERS_HLSL)
set(OUTPUT_FILES "")
set(HLSL_TARGET_NAME ${PROJECT_NAME}-HLSL)
Expand Down Expand Up @@ -241,9 +242,11 @@ endif()
add_custom_command(
OUTPUT ${OUTPUT_FILE}
COMMAND ${Vulkan_dxc_EXECUTABLE} -spirv -T ${DXC_PROFILE} -E main ${TARGET_DXC_ADDITIONAL_ARGUMENTS} ${SHADER_FILE_HLSL} -Fo ${OUTPUT_FILE}
COMMAND ${CMAKE_COMMAND} -E copy ${OUTPUT_FILE} ${directory}
MAIN_DEPENDENCY ${SHADER_FILE_HLSL}
# Only update checked-in shader binaries if contents differ to prevent needless timestamp churn
COMMAND ${CMAKE_COMMAND} -E copy_if_different ${OUTPUT_FILE} ${directory}
DEPENDS ${SHADER_FILE_HLSL}
WORKING_DIRECTORY ${CMAKE_SOURCE_DIR}
VERBATIM
)
list(APPEND OUTPUT_FILES ${OUTPUT_FILE})
set_source_files_properties(${OUTPUT_FILE} PROPERTIES
Expand Down Expand Up @@ -282,9 +285,10 @@ endif()
add_custom_command(
OUTPUT ${OUTPUT_FILE}
COMMAND ${Vulkan_slang_EXECUTABLE} ${SHADER_FILE_SLANG} -profile ${SLANG_PROFILE} -matrix-layout-column-major -target spirv -o ${OUTPUT_FILE} -entry ${SLANG_ENTRY_POINT}
COMMAND ${CMAKE_COMMAND} -E copy ${OUTPUT_FILE} ${directory}
MAIN_DEPENDENCY ${SHADER_FILE_SLANG}
COMMAND ${CMAKE_COMMAND} -E copy_if_different ${OUTPUT_FILE} ${directory}
DEPENDS ${SHADER_FILE_SLANG}
WORKING_DIRECTORY ${CMAKE_SOURCE_DIR}
VERBATIM
)
list(APPEND OUTPUT_FILES ${OUTPUT_FILE})
set_source_files_properties(${OUTPUT_FILE} PROPERTIES
Expand Down Expand Up @@ -328,9 +332,10 @@ endif()
add_custom_command(
OUTPUT ${OUTPUT_FILE}
COMMAND ${COMPILE_COMMAND}
COMMAND ${CMAKE_COMMAND} -E copy ${OUTPUT_FILE} ${directory}
MAIN_DEPENDENCY ${SHADER_FILE_GLSL}
COMMAND ${CMAKE_COMMAND} -E copy_if_different ${OUTPUT_FILE} ${directory}
DEPENDS ${SHADER_FILE_GLSL}
WORKING_DIRECTORY ${CMAKE_SOURCE_DIR}
VERBATIM
)
list(APPEND OUTPUT_FILES ${OUTPUT_FILE})
set_source_files_properties(${OUTPUT_FILE} PROPERTIES
Expand All @@ -357,9 +362,10 @@ endif()
add_custom_command(
OUTPUT ${OUTPUT_FILE}
COMMAND ${Vulkan_spirvas_EXECUTABLE} ${SHADER_FILE_SPVASM} -o ${OUTPUT_FILE} ${TARGET_SPVASM_ADDITIONAL_ARGUMENTS}
COMMAND ${CMAKE_COMMAND} -E copy ${OUTPUT_FILE} ${directory}
MAIN_DEPENDENCY ${SHADER_FILE_SPVASM}
COMMAND ${CMAKE_COMMAND} -E copy_if_different ${OUTPUT_FILE} ${directory}
DEPENDS ${SHADER_FILE_SPVASM}
WORKING_DIRECTORY ${CMAKE_SOURCE_DIR}
VERBATIM
)
list(APPEND OUTPUT_FILES ${OUTPUT_FILE})
set_source_files_properties(${OUTPUT_FILE} PROPERTIES
Expand Down
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