From d58fe4ccfa6417eb8440f49f487273376cd8560f Mon Sep 17 00:00:00 2001
From: Alexandros Lamprineas <alexandros.lamprineas@arm.com>
Date: Thu, 31 Oct 2024 09:59:16 +0000
Subject: [PATCH] [FMV][AArch64] Remove features which expose non exploitable
 runtime behavior.

Feature dit provides independent timing for data processing instructions
according to the value CPSR.DIT of the Current Program Status Register.

The runtime detection in FMV does not examine the content of control
registers, therefore such features are not suitable for runtime dispatch
since they cannot be exploited in a meaningful way. See the ACLE patch
for more info: https://github.com/ARM-software/acle/pull/355

Depends on https://github.com/llvm/llvm-project/pull/114387
---
 SingleSource/UnitTests/AArch64/acle-fmv-features.c         | 7 -------
 .../UnitTests/AArch64/acle-fmv-features.reference_output   | 1 -
 2 files changed, 8 deletions(-)

diff --git a/SingleSource/UnitTests/AArch64/acle-fmv-features.c b/SingleSource/UnitTests/AArch64/acle-fmv-features.c
index 0385ec1958..dc5919d23b 100644
--- a/SingleSource/UnitTests/AArch64/acle-fmv-features.c
+++ b/SingleSource/UnitTests/AArch64/acle-fmv-features.c
@@ -162,12 +162,6 @@ CHECK(i8mm, i8mm, i8mm, false, {
         : : : "v0"
     );
 })
-CHECK(dit, dit, dit, false, {
-    asm volatile (
-        "msr DIT, x0"
-        : : : "x0"
-    );
-})
 CHECK(fp16, fp16, fp16, false, {
     asm volatile (
         "fmov h0, #0"
@@ -409,7 +403,6 @@ int main(int, const char **) {
     check_dpb2();
     check_bf16();
     check_i8mm();
-    check_dit();
     check_fp16();
     check_ssbs();
     check_bti();
diff --git a/SingleSource/UnitTests/AArch64/acle-fmv-features.reference_output b/SingleSource/UnitTests/AArch64/acle-fmv-features.reference_output
index 2c646c696c..40b9b4ce8b 100644
--- a/SingleSource/UnitTests/AArch64/acle-fmv-features.reference_output
+++ b/SingleSource/UnitTests/AArch64/acle-fmv-features.reference_output
@@ -14,7 +14,6 @@ dpb
 dpb2
 bf16
 i8mm
-dit
 fp16
 ssbs
 bti