[llvm] Revert "[llvm-exegesis][AArch64] Disable pauth and ldgm as unsupporte… (PR #134971)

[Madhur Amilkanthwar via llvm-commits]

https://github.com/madhur13490 created https://github.com/llvm/llvm-project/pull/134971

…d instructions (#132346)"

This reverts commit 559540dc2738af0ab3f0b48eb4993095b8a8c627 as it has cause build failures in llvm-clang-x86_64-gcc-ubuntu

>From a819aa5cebe6886084f8f5485ca22729ed443e82 Mon Sep 17 00:00:00 2001
From: Madhur Amilkanthwar <madhura at nvidia.com>
Date: Tue, 8 Apr 2025 23:24:16 -0700
Subject: [PATCH] Revert "[llvm-exegesis][AArch64] Disable pauth and ldgm as
 unsupported instructions (#132346)"

This reverts commit 559540dc2738af0ab3f0b48eb4993095b8a8c627 as it
has cause build failures in llvm-clang-x86_64-gcc-ubuntu
---
 .../AArch64/skip_unsupported_instructions.s   |  8 --
 .../llvm-exegesis/lib/AArch64/Target.cpp      | 75 -------------------
 2 files changed, 83 deletions(-)
 delete mode 100644 llvm/test/tools/llvm-exegesis/AArch64/skip_unsupported_instructions.s

diff --git a/llvm/test/tools/llvm-exegesis/AArch64/skip_unsupported_instructions.s b/llvm/test/tools/llvm-exegesis/AArch64/skip_unsupported_instructions.s
deleted file mode 100644
index acefbce2e94c5..0000000000000
--- a/llvm/test/tools/llvm-exegesis/AArch64/skip_unsupported_instructions.s
+++ /dev/null
@@ -1,8 +0,0 @@
-# REQUIRES: aarch64-registered-target
-
-# Check for skipping of illegal instruction errors (AUT and LDGM)
-# RUN: llvm-exegesis -mcpu=neoverse-v2 -mode=latency --opcode-name=AUTIA --benchmark-phase=assemble-measured-code 2>&1 | FileCheck %s --check-prefix=CHECK-AUTIA
-# CHECK-AUTIA-NOT: snippet crashed while running: Illegal instruction
-
-# RUN: llvm-exegesis -mcpu=neoverse-v2 -mode=latency --opcode-name=LDGM --benchmark-phase=assemble-measured-code 2>&1 | FileCheck %s --check-prefix=CHECK-LDGM
-# CHECK-LDGM: LDGM: Unsupported opcode: load tag multiple 
diff --git a/llvm/tools/llvm-exegesis/lib/AArch64/Target.cpp b/llvm/tools/llvm-exegesis/lib/AArch64/Target.cpp
index 1aca258603590..bf2b053003ce3 100644
--- a/llvm/tools/llvm-exegesis/lib/AArch64/Target.cpp
+++ b/llvm/tools/llvm-exegesis/lib/AArch64/Target.cpp
@@ -9,58 +9,12 @@
 #include "AArch64.h"
 #include "AArch64RegisterInfo.h"
 
-#ifdef __linux__
-#include <linux/prctl.h> // For PR_PAC_* constants
-#include <sys/prctl.h>
-#endif
-
 #define GET_AVAILABLE_OPCODE_CHECKER
 #include "AArch64GenInstrInfo.inc"
 
 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:
@@ -180,35 +134,6 @@ 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)) {
-#ifdef __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