Add neoverse-512tvb optimization build flag and gate it behind CPU detection - #82
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Add neoverse-512tvb optimization build flag and gate it behind CPU detection#82subhramit wants to merge 1 commit into
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…ehind CPU detection `lore-base/build.rs` passed `-mcpu=neoverse-512tvb` unconditionally to the C compiler for all `linux/aarch64` targets, causing binaries to crash with `illegal hardware instruction` on hardware that does not implement SVE2 and other Neoverse 512TVB extensions. Introduce a `neoverse-512tvb` Cargo feature to opt in to the optimization, and gate it behind a `/proc/cpuinfo` SVE2 check so the flag is only applied when the hardware supports it. Fixes EpicGames#42 Signed-off-by: subhramit <subhramit.bb@live.in>
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| if cpuinfo.contains("sve2") { | ||
| cc_builder.flag("-mcpu=neoverse-512tvb"); | ||
| } else { | ||
| println!( | ||
| "cargo:warning=LORE_CPU_NEOVERSE_512TVB is set but SVE2 not detected in /proc/cpuinfo; skipping -mcpu=neoverse-512tvb and building for generic aarch64 to avoid illegal hardware instruction. Disable the `neoverse-512tvb` feature to suppress this warning" | ||
| ); | ||
| } |
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We could also force respecting the flag setting irrespective of cpu info:
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| if cpuinfo.contains("sve2") { | |
| cc_builder.flag("-mcpu=neoverse-512tvb"); | |
| } else { | |
| println!( | |
| "cargo:warning=LORE_CPU_NEOVERSE_512TVB is set but SVE2 not detected in /proc/cpuinfo; skipping -mcpu=neoverse-512tvb and building for generic aarch64 to avoid illegal hardware instruction. Disable the `neoverse-512tvb` feature to suppress this warning" | |
| ); | |
| } | |
| if !cpuinfo.contains("sve2") { | |
| println!( | |
| "cargo:warning=LORE_CPU_NEOVERSE_512TVB is set but SVE2 not detected in /proc/cpuinfo; binary may crash with illegal hardware instruction. Unset the `neoverse-512tvb` feature to build for generic aarch64" | |
| ); | |
| cc_builder.flag("-mcpu=neoverse-512tvb"); | |
| } |
in case we are looking forward to cross-compilation cases, so I leave it upto your decision @mjansson @valentina2509
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I think we are restructuring the compilation for various platforms and CPU tuning a bit to handle building both vanilla arm64 and tuned for Gravitons. That work should be done soon and supersede this change. |
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Part of cross-platform build portability.
Fixes #42
lore-base/build.rspassed-mcpu=neoverse-512tvbunconditionally to the C compiler for all linux/aarch64 targets, causing binaries to crash withillegal hardware instructionon hardware that does not implement SVE2 and other Neoverse 512TVB extensions. This introduces a neoverse-512tvb build flag to opt-in to the optimization, and gates it behind a/proc/cpuinfoSVE2 check, falling back to a generic aarch64 build with a warning if it is not detected.