[LoongArch] Add "32bit" target feature

There are a few intrinsics or instructions on LoongArch
that are only appropriate for loongarch32 target. So the
feature "32bit" is added to implement it.

Reviewed By: SixWeining

Differential Revision: https://reviews.llvm.org/D140872

Author: XiaodongLoong

llvm/lib/Target/LoongArch/LoongArch.td

@@ -17,6 +17,9 @@ include "llvm/Target/Target.td"
 def Feature64Bit
     : SubtargetFeature<"64bit", "HasLA64", "true",
                        "LA64 Basic Integer and Privilege Instruction Set">;
+def Feature32Bit
+    : SubtargetFeature<"32bit", "HasLA32", "true",
+                       "LA32 Basic Integer and Privilege Instruction Set">;
 def IsLA64
     : Predicate<"Subtarget->is64Bit()">,
       AssemblerPredicate<(all_of Feature64Bit),
@@ -124,7 +127,7 @@ include "LoongArchInstrInfo.td"
 // LoongArch processors supported.
 //===----------------------------------------------------------------------===//
 
-def : ProcessorModel<"generic-la32", NoSchedModel, []>;
+def : ProcessorModel<"generic-la32", NoSchedModel, [Feature32Bit]>;
 def : ProcessorModel<"generic-la64", NoSchedModel, [Feature64Bit]>;
 
 // Support generic for compatibility with other targets. The triple will be used

llvm/lib/Target/LoongArch/LoongArchSubtarget.cpp

@@ -39,6 +39,15 @@ LoongArchSubtarget &LoongArchSubtarget::initializeSubtargetDependencies(
     GRLen = 64;
   }
 
+  if (HasLA32 == HasLA64)
+    report_fatal_error("Please use one feature of 32bit and 64bit.");
+
+  if (Is64Bit && HasLA32)
+    report_fatal_error("Feature 32bit should be used for loongarch32 target.");
+
+  if (!Is64Bit && HasLA64)
+    report_fatal_error("Feature 64bit should be used for loongarch64 target.");
+
   // TODO: ILP32{S,F} LP64{S,F}
   TargetABI = Is64Bit ? LoongArchABI::ABI_LP64D : LoongArchABI::ABI_ILP32D;
   return *this;

llvm/lib/Target/LoongArch/LoongArchSubtarget.h

@@ -31,6 +31,7 @@ class StringRef;
 
 class LoongArchSubtarget : public LoongArchGenSubtargetInfo {
   virtual void anchor();
+  bool HasLA32 = false;
   bool HasLA64 = false;
   bool HasBasicF = false;
   bool HasBasicD = false;

llvm/test/CodeGen/LoongArch/feature-32bit.ll

@@ -0,0 +1,5 @@
+; RUN: llc --mtriple=loongarch64 --mattr=help 2>&1 | FileCheck %s
+; RUN: llc --mtriple=loongarch32 --mattr=help 2>&1 | FileCheck %s
+
+; CHECK: Available features for this target:
+; CHECK: 32bit - LA32 Basic Integer and Privilege Instruction Set.