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Pick native DXC and Slang binaries on Arm64 Windows hosts - #26
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dzhdanNV merged 1 commit intoSep 29, 2026
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The arch check matched "arm64" case-sensitively against CMAKE_SYSTEM_PROCESSOR, which CMake reports as "ARM64" on Windows, so Arm64 hosts always got the x64 compilers and ran them under emulation. The compilers run on the build host, so test CMAKE_HOST_SYSTEM_PROCESSOR case-insensitively instead. Native DXC compiles ~2x faster (550 vs 1081 ms on a DXR library shader) with identical output. An x64 cmake.exe reports AMD64 under emulation, so it still selects the x64 tools.
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The DXC/FXC/Slang arch check matched "arm64" case-sensitively against
CMAKE_SYSTEM_PROCESSOR, which Windows CMake reports asARM64, so Arm64 Windowshosts always downloaded and ran the x64 compilers under emulation.
The compilers run on the build host, so this tests
CMAKE_HOST_SYSTEM_PROCESSORcase-insensitively instead. Shader output is unchanged; only the compiler binary
that runs is different.
Measured on an Arm64 Windows host, CMake 4.4.3:
cmake.exeARM64AMD64CMake reports the architecture of
cmake.exeitself, so the fix takes effect with anative Arm64 CMake.
Compiling a 2,100-line DXR library shader (
-T lib_6_6 -O3) with DXC v1.9.2602:native arm64
dxc.exe550 ms vs x64 under emulation 1081 ms (median of 5), about2x faster, with byte-identical DXIL output.
x64 hosts are unaffected, including x64-hosted
-A ARM64Visual Studio cross builds,which still select
bin/x64/dxc.exe.