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Revert "[llvm-exegesis][AArch64] Disable pauth and ldgm as unsupported instructions fixed (#136868)" #142382

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Merged
merged 1 commit into from
Jun 2, 2025
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Revert "[llvm-exegesis][AArch64] Disable pauth and ldgm as unsupported instructions fixed (#136868)" #142382

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14 changes: 0 additions & 14 deletions llvm/test/tools/llvm-exegesis/AArch64/skip_unsupported_instructions.s
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76 changes: 0 additions & 76 deletions llvm/tools/llvm-exegesis/lib/AArch64/Target.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -12,12 +12,6 @@
#if defined(__aarch64__) && defined(__linux__)
#include <linux/prctl.h> // For PR_PAC_* constants
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Can you also remove this header due to #139443

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@abhilash1910 I believe that would require to also revert 36850a0 and 5dc3cd0 because they depend on this header.

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I think this header is duplicated in sys/prctl.h ; but sure we can keep it and remove safely in my PR. Thanks

#include <sys/prctl.h>
#ifndef PR_PAC_SET_ENABLED_KEYS
#define PR_PAC_SET_ENABLED_KEYS 60
#endif
#ifndef PR_PAC_GET_ENABLED_KEYS
#define PR_PAC_GET_ENABLED_KEYS 61
#endif
#ifndef PR_PAC_APIAKEY
#define PR_PAC_APIAKEY (1UL << 0)
#endif
Expand All @@ -38,47 +32,6 @@
namespace llvm {
namespace exegesis {

bool isPointerAuth(unsigned Opcode) {
switch (Opcode) {
default:
return false;

// FIXME: Pointer Authentication instructions.
// We would like to measure these instructions, but they can behave
// differently on different platforms, and maybe the snippets need to look
// different for these instructions,
// Platform-specific handling: On Linux, we disable authentication, may
// interfere with measurements. On non-Linux platforms, disable opcodes for
// now.
case AArch64::AUTDA:
case AArch64::AUTDB:
case AArch64::AUTDZA:
case AArch64::AUTDZB:
case AArch64::AUTIA:
case AArch64::AUTIA1716:
case AArch64::AUTIASP:
case AArch64::AUTIAZ:
case AArch64::AUTIB:
case AArch64::AUTIB1716:
case AArch64::AUTIBSP:
case AArch64::AUTIBZ:
case AArch64::AUTIZA:
case AArch64::AUTIZB:
return true;
}
}

bool isLoadTagMultiple(unsigned Opcode) {
switch (Opcode) {
default:
return false;

// Load tag multiple instruction
case AArch64::LDGM:
return true;
}
}

static unsigned getLoadImmediateOpcode(unsigned RegBitWidth) {
switch (RegBitWidth) {
case 32:
Expand Down Expand Up @@ -198,35 +151,6 @@ class ExegesisAArch64Target : public ExegesisTarget {
// Function return is a pseudo-instruction that needs to be expanded
PM.add(createAArch64ExpandPseudoPass());
}

const char *getIgnoredOpcodeReasonOrNull(const LLVMState &State,
unsigned Opcode) const override {
if (const char *Reason =
ExegesisTarget::getIgnoredOpcodeReasonOrNull(State, Opcode))
return Reason;

if (isPointerAuth(Opcode)) {
#if defined(__aarch64__) && defined(__linux__)
// Disable all PAC keys. Note that while we expect the measurements to
// be the same with PAC keys disabled, they could potentially be lower
// since authentication checks are bypassed.
if (prctl(PR_PAC_SET_ENABLED_KEYS,
PR_PAC_APIAKEY | PR_PAC_APIBKEY | PR_PAC_APDAKEY |
PR_PAC_APDBKEY, // all keys
0, // disable all
0, 0) < 0) {
return "Failed to disable PAC keys";
}
#else
return "Unsupported opcode: isPointerAuth";
#endif
}

if (isLoadTagMultiple(Opcode))
return "Unsupported opcode: load tag multiple";

return nullptr;
}
};

} // namespace
Expand Down
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