Skip to content

[llvm-exegesis][AArch64] Disable pauth and ldgm as unsupported instructions #132346

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
madhur13490 merged 11 commits into from
Apr 9, 2025
Merged

[llvm-exegesis][AArch64] Disable pauth and ldgm as unsupported instructions #132346

Show file tree
Hide file tree
Changes from 2 commits
Commits
Show all changes
11 commits
Select commit Hold shift + click to select a range
f1e1d7a
[llvm-exegesis] [AArch64] Resolving Illegal Instruction Error
lakshayk-nv Mar 21, 2025
5039c2b
[llvm-exegesis] [AArch64] Use enum values for opcode validation
lakshayk-nv Mar 24, 2025
6b81e65
[llvm-exegesis][AArch64] Disable pauth and ldgm as unsupported instru…
lakshayk-nv Mar 26, 2025
bef8e21
Merge branch 'main' of https://github.com/llvm/llvm-project into llvm…
lakshayk-nv Apr 1, 2025
dade502
[llvm-exegesis][AArch64] Formatting changes
lakshayk-nv Apr 1, 2025
b6ce448
[llvm-exegesis] Add Linux PR_PAC_* constants and update opcode handling
lakshayk-nv Apr 1, 2025
783f86d
[llvm-exegesis][AArch64] Updated the testcase for AUT instruction class.
lakshayk-nv Apr 1, 2025
70eb3bf
[llvm-exegesis][AArch64] Refactor opcode handling for pointer authent…
lakshayk-nv Apr 3, 2025
a1fedb4
[llvm-exegesis][AArch64] Enhance pointer authentication handling for …
lakshayk-nv Apr 3, 2025
06fbe30
Revert "[llvm-exegesis][AArch64] Formatting changes"
lakshayk-nv Apr 4, 2025
3af87a0
[llvm-exegesis][AArch64] Revert back unnecessary unfolded error and f…
lakshayk-nv Apr 7, 2025
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
8 changes: 8 additions & 0 deletions llvm/test/tools/llvm-exegesis/AArch64/err_skip_illegal_Instruction.s
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1,8 @@
# REQUIRES: aarch64-registered-target
Copy link
Collaborator

@sjoerdmeijer sjoerdmeijer Mar 25, 2025

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Nitpick about the filename err_skip_illegal_Instruction.s: they are not illegal instructions per se, it's more that they are unsupported (at the moment), and also one word is capitalised and the other aren't so is a bit inconsistent. My suggestion would be skip_unsupported_instructions.s or something like that.

Copy link
Contributor Author

@lakshayk-nv lakshayk-nv Mar 25, 2025

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

I originally named it err_skip_illegal_Instruction.s to indicate it's a test case for error skipping behavior, but you're right that skip_unsupported_instructions.s would be more accurate since these instructions are unsupported rather than illegal. I will push required changes.

Btw, Can you weigh in for checking other skipped errors (isPseudo, isReturn etc.).
Does it make sense to check them also in this testfile, (just for completeness) ?


# 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
# CHECK: AUTIA: Unsupported opcode: isPointerAuth/isUncheckedAccess

# RUN: llvm-exegesis -mcpu=neoverse-v2 -mode=latency --opcode-name=LDGM --benchmark-phase=assemble-measured-code 2>&1
# CHECK: LDGM: Unsupported opcode: isPointerAuth/isUncheckedAccess
4 changes: 4 additions & 0 deletions llvm/tools/llvm-exegesis/lib/CMakeLists.txt
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -1,3 +1,7 @@
include_directories(
${LLVM_MAIN_SRC_DIR}/lib/Target/AArch64
${LLVM_BINARY_DIR}/lib/Target/AArch64
)

set(LLVM_EXEGESIS_TARGETS)
if (LLVM_TARGETS_TO_BUILD MATCHES "X86")
Expand Down
35 changes: 35 additions & 0 deletions llvm/tools/llvm-exegesis/lib/Target.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -15,6 +15,8 @@
#include "llvm/ADT/Twine.h"
#include "llvm/Support/Error.h"
#include "llvm/TargetParser/SubtargetFeature.h"
#include "AArch64.h"
#include "AArch64RegisterInfo.h"

namespace llvm {
namespace exegesis {
Expand All @@ -35,6 +37,37 @@ const ExegesisTarget *ExegesisTarget::lookup(Triple TT) {
return nullptr;
}

static bool isPointerAuthOpcode(unsigned Opcode) {
Copy link
Collaborator

@sjoerdmeijer sjoerdmeijer Mar 25, 2025

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Another nitpick, I wanted to suggest that we create one isUnsupportedOpcode() function that could use these new helper functions, but then realised that is function getIgnoredOpcodeReasonOrNull(). We might as well use that function then, here would be my suggestion and as you see I also split up the first couple of if-statements as I don't like error messages that say "it can be this or that":

    const char *
    ExegesisTarget::getIgnoredOpcodeReasonOrNull(const LLVMState &State,
                                             unsigned Opcode) const {
        const MCInstrDesc &InstrDesc = State.getIC().getInstr(Opcode).Description;

        if (InstrDesc.isPseudo())
          return "Unsupported opcode: isPseudo";
        if ( InstrDesc.usesCustomInsertionHook())
          return "Unsupported opcode: usesCustomInserter";
        if (InstrDesc.isBranch())
          return "Unsupported opcode: isBranch";
        if (InstrDesc.isIndirectBranch())
          return "Unsupported opcode: isIndirectBranch";
        if (InstrDesc.isCall())
          return "Unsupported opcode: isCall";
        if (InstrDesc.isReturn())
          return "Unsupported opcode: isReturn";

         switch (Opcode) {
         default:
           return nullptr;

         // 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,
         // so let's disable this 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 ""Unsupported opcode: isPointerAuth";

         // Load tag multiple instruction
         case AArch64::LDGM:
           return "Unsupported opcode: load tag multiple";
       }
       return nullptr;
    }

switch (Opcode) {
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;
default:
return false;
}
}

static bool isUncheckedAccessOpcode(unsigned Opcode) {
switch (Opcode) {
case AArch64::LDGM:
return true;
default:
return false;
}
}

const char *
ExegesisTarget::getIgnoredOpcodeReasonOrNull(const LLVMState &State,
unsigned Opcode) const {
Expand All @@ -45,6 +78,8 @@ ExegesisTarget::getIgnoredOpcodeReasonOrNull(const LLVMState &State,
return "Unsupported opcode: isBranch/isIndirectBranch";
if (InstrDesc.isCall() || InstrDesc.isReturn())
return "Unsupported opcode: isCall/isReturn";
if (isPointerAuthOpcode(Opcode) || isUncheckedAccessOpcode(Opcode))
return "Unsupported opcode: isPointerAuth/isUncheckedAccess";
return nullptr;
}

Expand Down
Loading