[Clang] Remove preprocessor guards and global feature checks for NEON (#95224)

To enable function multi-versioning (FMV), current checks which rely on
cmd line options or global macros to see if target feature is present
need to be removed. This patch removes those for NEON and also
implements changes to NEON header file as proposed in
[ACLE](ARM-software/acle#321).

Author: Lukacma

clang/include/clang/Basic/DiagnosticSemaKinds.td

@@ -3246,6 +3246,9 @@ def warn_unsupported_target_attribute
 def err_attribute_unsupported
     : Error<"%0 attribute is not supported on targets missing %1;"
             " specify an appropriate -march= or -mcpu=">;
+def err_attribute_unsupported_m_profile
+    : Error<"on M-profile architectures %0 attribute is not supported on targets missing %1;"
+            " specify an appropriate -march= or -mcpu=">;
 def err_duplicate_target_attribute
     : Error<"%select{unsupported|duplicate|unknown}0%select{| CPU|"
               " tune CPU}1 '%2' in the '%select{target|target_clones|target_version}3' "

clang/lib/Sema/SemaType.cpp

@@ -8203,23 +8203,19 @@ static void HandleNeonVectorTypeAttr(QualType &CurType, const ParsedAttr &Attr,
 
   // Target must have NEON (or MVE, whose vectors are similar enough
   // not to need a separate attribute)
-  if (!(S.Context.getTargetInfo().hasFeature("neon") ||
-        S.Context.getTargetInfo().hasFeature("mve") ||
-        S.Context.getTargetInfo().hasFeature("sve") ||
-        S.Context.getTargetInfo().hasFeature("sme") ||
-        IsTargetCUDAAndHostARM) &&
-      VecKind == VectorKind::Neon) {
-    S.Diag(Attr.getLoc(), diag::err_attribute_unsupported)
-        << Attr << "'neon', 'mve', 'sve' or 'sme'";
+  if (!S.Context.getTargetInfo().hasFeature("mve") &&
+      VecKind == VectorKind::Neon &&
+      S.Context.getTargetInfo().getTriple().isArmMClass()) {
+    S.Diag(Attr.getLoc(), diag::err_attribute_unsupported_m_profile)
+        << Attr << "'mve'";
     Attr.setInvalid();
     return;
   }
-  if (!(S.Context.getTargetInfo().hasFeature("neon") ||
-        S.Context.getTargetInfo().hasFeature("mve") ||
-        IsTargetCUDAAndHostARM) &&
-      VecKind == VectorKind::NeonPoly) {
-    S.Diag(Attr.getLoc(), diag::err_attribute_unsupported)
-        << Attr << "'neon' or 'mve'";
+  if (!S.Context.getTargetInfo().hasFeature("mve") &&
+      VecKind == VectorKind::NeonPoly &&
+      S.Context.getTargetInfo().getTriple().isArmMClass()) {
+    S.Diag(Attr.getLoc(), diag::err_attribute_unsupported_m_profile)
+        << Attr << "'mve'";
     Attr.setInvalid();
     return;
   }

clang/test/Sema/arm-vector-types-support.c

@@ -1,7 +1,8 @@
-// RUN: %clang_cc1 %s -triple armv7 -fsyntax-only -verify
-// RUN: %clang_cc1 %s -triple aarch64 -fsyntax-only -verify
-// RUN: %clang_cc1 %s -triple aarch64 -target-feature -fp-armv8 -target-abi aapcs-soft -fsyntax-only -verify
+// RUN: %clang_cc1 %s -triple armv8.1m.main -fsyntax-only -verify
+// RUN: %clang_cc1 %s -triple aarch64 -fsyntax-only -verify=sve-type
+// RUN: %clang_cc1 %s -triple aarch64 -target-feature -fp-armv8 -target-abi aapcs-soft -fsyntax-only -verify=sve-type
 
-typedef __attribute__((neon_vector_type(2))) int int32x2_t; // expected-error{{'neon_vector_type' attribute is not supported on targets missing 'neon', 'mve', 'sve' or 'sme'; specify an appropriate -march= or -mcpu=}}
-typedef __attribute__((neon_polyvector_type(16))) short poly8x16_t; // expected-error{{'neon_polyvector_type' attribute is not supported on targets missing 'neon' or 'mve'; specify an appropriate -march= or -mcpu=}}
+typedef __attribute__((neon_vector_type(2))) int int32x2_t; // expected-error{{on M-profile architectures 'neon_vector_type' attribute is not supported on targets missing 'mve'; specify an appropriate -march= or -mcpu=}}
+typedef __attribute__((neon_polyvector_type(16))) unsigned char poly8x16_t; // expected-error{{on M-profile architectures 'neon_polyvector_type' attribute is not supported on targets missing 'mve'; specify an appropriate -march= or -mcpu=}}
 typedef __attribute__((arm_sve_vector_bits(256))) void nosveflag; // expected-error{{'arm_sve_vector_bits' attribute is not supported on targets missing 'sve'; specify an appropriate -march= or -mcpu=}}
+                                                                  // sve-type-error@-1{{'arm_sve_vector_bits' attribute is not supported on targets missing 'sve'; specify an appropriate -march= or -mcpu=}}

clang/test/SemaCUDA/neon-attrs.cu

@@ -2370,10 +2370,6 @@ void NeonEmitter::run(raw_ostream &OS) {
         "Please use -mfloat-abi=softfp or -mfloat-abi=hard\"\n";
   OS << "#else\n\n";
 
-  OS << "#if !defined(__ARM_NEON)\n";
-  OS << "#error \"NEON support not enabled\"\n";
-  OS << "#else\n\n";
-
   OS << "#include <stdint.h>\n\n";
 
   OS << "#include <arm_bf16.h>\n";
@@ -2450,7 +2446,6 @@ void NeonEmitter::run(raw_ostream &OS) {
   OS << "#undef __ai\n\n";
   OS << "#endif /* if !defined(__ARM_NEON) */\n";
   OS << "#endif /* ifndef __ARM_FP */\n";
-  OS << "#endif /* __ARM_NEON_H */\n";
 }
 
 /// run - Read the records in arm_fp16.td and output arm_fp16.h.  arm_fp16.h