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[TargetParser][AArch64] Believe runtime feature detection #95694

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Merged
merged 2 commits into from
Oct 2, 2024
Merged

[TargetParser][AArch64] Believe runtime feature detection #95694

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fcd62f6
[TargetParser][AArch64] Believe runtime feature detection
workingjubilee Jun 16, 2024
0d9373c
[TargetParser][AArch64] Split crypto feature detection into AES & SHA2
workingjubilee Jun 17, 2024
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30 changes: 20 additions & 10 deletions llvm/lib/TargetParser/Host.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1898,7 +1898,8 @@ const StringMap<bool> sys::getHostCPUFeatures() {
}

#if defined(__aarch64__)
// Keep track of which crypto features we have seen
// All of these are "crypto" features, but we must sift out actual features
// as the former meaning of "crypto" as a single feature is no more.
enum { CAP_AES = 0x1, CAP_PMULL = 0x2, CAP_SHA1 = 0x4, CAP_SHA2 = 0x8 };
uint32_t crypto = 0;
#endif
Expand Down Expand Up @@ -1941,9 +1942,13 @@ const StringMap<bool> sys::getHostCPUFeatures() {
}

#if defined(__aarch64__)
// If we have all crypto bits we can add the feature
if (crypto == (CAP_AES | CAP_PMULL | CAP_SHA1 | CAP_SHA2))
Features["crypto"] = true;
// LLVM has decided some AArch64 CPUs have all the instructions they _may_
// have, as opposed to all the instructions they _must_ have, so allow runtime
// information to correct us on that.
uint32_t Aes = CAP_AES | CAP_PMULL;
uint32_t Sha2 = CAP_SHA1 | CAP_SHA2;
Features["aes"] = (crypto & Aes) == Aes;
Features["sha2"] = (crypto & Sha2) == Sha2;
#endif

return Features;
Expand All @@ -1952,12 +1957,17 @@ const StringMap<bool> sys::getHostCPUFeatures() {
const StringMap<bool> sys::getHostCPUFeatures() {
StringMap<bool> Features;

if (IsProcessorFeaturePresent(PF_ARM_NEON_INSTRUCTIONS_AVAILABLE))
Features["neon"] = true;
if (IsProcessorFeaturePresent(PF_ARM_V8_CRC32_INSTRUCTIONS_AVAILABLE))
Features["crc"] = true;
if (IsProcessorFeaturePresent(PF_ARM_V8_CRYPTO_INSTRUCTIONS_AVAILABLE))
Features["crypto"] = true;
// If we're asking the OS at runtime, believe what the OS says
Features["neon"] =
IsProcessorFeaturePresent(PF_ARM_NEON_INSTRUCTIONS_AVAILABLE);
Features["crc"] =
IsProcessorFeaturePresent(PF_ARM_V8_CRC32_INSTRUCTIONS_AVAILABLE);

// Avoid inferring "crypto" means more than the traditional AES + SHA2
bool TradCrypto =
IsProcessorFeaturePresent(PF_ARM_V8_CRYPTO_INSTRUCTIONS_AVAILABLE);
Features["aes"] = TradCrypto;
Features["sha2"] = TradCrypto;

return Features;
}
Expand Down
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