From e32b818db187a6519ee5eba47e8d7dae1d58a723 Mon Sep 17 00:00:00 2001
From: Ties Stuij <ties.stuij@arm.com>
Date: Thu, 9 Dec 2021 09:40:46 +0000
Subject: [PATCH] [ARM][clang] Define feature test macro for the PACBTI-M
 extension

If the extension string "+pacbti" was given in -march=... or -mcpu=... options the compiler shall define the following preprocessor macros:

    __ARM_FEATURE_PAUTH with value 1.
    __ARM_FEATURE_BTI with value 1.

This patch is part of a series that adds support for the PACBTI-M extension of
the Armv8.1-M architecture, as detailed here:

https://community.arm.com/arm-community-blogs/b/architectures-and-processors-blog/posts/armv8-1-m-pointer-authentication-and-branch-target-identification-extension

The PACBTI-M specification can be found in the Armv8-M Architecture Reference
Manual:

https://developer.arm.com/documentation/ddi0553/latest

The following people contributed to this patch:

- Momchil Velikov
- Ties Stuij

Reviewed By: miyuki

Differential Revision: https://reviews.llvm.org/D112431
---
 clang/lib/Basic/Targets/ARM.cpp               | 11 +++++++++++
 clang/lib/Basic/Targets/ARM.h                 |  2 ++
 clang/test/Preprocessor/arm-target-features.c |  7 +++++++
 3 files changed, 20 insertions(+)

diff --git a/clang/lib/Basic/Targets/ARM.cpp b/clang/lib/Basic/Targets/ARM.cpp
index f330780..81b79cf 100644
--- a/clang/lib/Basic/Targets/ARM.cpp
+++ b/clang/lib/Basic/Targets/ARM.cpp
@@ -465,6 +465,8 @@ bool ARMTargetInfo::handleTargetFeatures(std::vector<std::string> &Features,
   HWDiv = 0;
   DotProd = 0;
   HasMatMul = 0;
+  HasPAC = 0;
+  HasBTI = 0;
   HasFloat16 = true;
   ARMCDECoprocMask = 0;
   HasBFloat16 = false;
@@ -547,6 +549,9 @@ bool ARMTargetInfo::handleTargetFeatures(std::vector<std::string> &Features,
       HasBFloat16 = true;
     } else if (Feature == "-fpregs") {
       FPRegsDisabled = true;
+    } else if (Feature == "+pacbti") {
+      HasPAC = 1;
+      HasBTI = 1;
     }
   }
 
@@ -890,6 +895,12 @@ void ARMTargetInfo::getTargetDefines(const LangOptions &Opts,
   if (HasMatMul)
     Builder.defineMacro("__ARM_FEATURE_MATMUL_INT8", "1");
 
+  if (HasPAC)
+    Builder.defineMacro("__ARM_FEATURE_PAUTH", "1");
+
+  if (HasBTI)
+    Builder.defineMacro("__ARM_FEATURE_BTI", "1");
+
   if (HasBFloat16) {
     Builder.defineMacro("__ARM_FEATURE_BF16", "1");
     Builder.defineMacro("__ARM_FEATURE_BF16_VECTOR_ARITHMETIC", "1");
diff --git a/clang/lib/Basic/Targets/ARM.h b/clang/lib/Basic/Targets/ARM.h
index f939904..40c658f 100644
--- a/clang/lib/Basic/Targets/ARM.h
+++ b/clang/lib/Basic/Targets/ARM.h
@@ -79,6 +79,8 @@ class LLVM_LIBRARY_VISIBILITY ARMTargetInfo : public TargetInfo {
   unsigned DotProd : 1;
   unsigned HasMatMul : 1;
   unsigned FPRegsDisabled : 1;
+  unsigned HasPAC : 1;
+  unsigned HasBTI : 1;
 
   enum {
     LDREX_B = (1 << 0), /// byte (8-bit)
diff --git a/clang/test/Preprocessor/arm-target-features.c b/clang/test/Preprocessor/arm-target-features.c
index 7fb3323..49a5516 100644
--- a/clang/test/Preprocessor/arm-target-features.c
+++ b/clang/test/Preprocessor/arm-target-features.c
@@ -896,6 +896,13 @@
 // CHECK-PAC-LEAF: #define __ARM_FEATURE_PAC_DEFAULT 5
 // CHECK-PAC-BKEY-LEAF: #define __ARM_FEATURE_PAC_DEFAULT 6
 
+// RUN: %clang -target arm-arm-none-eabi -march=armv8.1-m.main -x c -E -dM %s -o - | FileCheck --check-prefixes=CHECK-NOBTI-EXT,CHECK-NOPAC-EXT %s
+// RUN: %clang -target arm-arm-none-eabi -march=armv7-m+pacbti -x c -E -dM %s -o - | FileCheck --check-prefixes=CHECK-PACBTI-EXT %s
+// CHECK-NOBTI-EXT-NOT: #define __ARM_FEATURE_BTI 1
+// CHECK-NOPAC-EXT-NOT: #define __ARM_FEATURE_PAUTH 1
+// CHECK-PACBTI-EXT: #define __ARM_FEATURE_BTI 1
+// CHECK-PACBTI-EXT: #define __ARM_FEATURE_PAUTH 1
+
 // ================== Check BFloat16 Extensions.
 // RUN: %clang -target arm-arm-none-eabi -march=armv8.6-a+bf16 -x c -E -dM %s -o - 2>&1 | FileCheck -check-prefix=CHECK-BFLOAT %s
 // CHECK-BFLOAT: #define __ARM_BF16_FORMAT_ALTERNATIVE 1
-- 
2.7.4