[LoongArch] Remove experimental auto-vec feature. (#100070)

Currently, automatic vectorization will be enabled with `-mlsx/-mlasx`
enabled.

Author: ylzsx

llvm/lib/Target/LoongArch/LoongArch.td

@@ -106,11 +106,6 @@ def FeatureRelax
     : SubtargetFeature<"relax", "HasLinkerRelax", "true",
                        "Enable Linker relaxation">;
 
-// Experimental auto vectorization
-def FeatureAutoVec
-    : SubtargetFeature<"auto-vec", "HasExpAutoVec", "true",
-                       "Experimental auto vectorization">;
-
 // Floating point approximation operation
 def FeatureFrecipe
     : SubtargetFeature<"frecipe", "HasFrecipe", "true",

llvm/lib/Target/LoongArch/LoongArchTargetTransformInfo.cpp

@@ -26,8 +26,6 @@ TypeSize LoongArchTTIImpl::getRegisterBitWidth(
   case TargetTransformInfo::RGK_Scalar:
     return TypeSize::getFixed(ST->is64Bit() ? 64 : 32);
   case TargetTransformInfo::RGK_FixedWidthVector:
-    if (!ST->hasExpAutoVec())
-      return DefSize;
     if (ST->hasExtLASX())
       return TypeSize::getFixed(256);
     if (ST->hasExtLSX())

llvm/test/Transforms/LoopVectorize/LoongArch/defaults.ll

@@ -1,5 +1,5 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 4
-; RUN: opt < %s -passes=loop-vectorize -mtriple loongarch64-linux-gnu -mattr=+lasx,+auto-vec -S | FileCheck %s
+; RUN: opt < %s -passes=loop-vectorize -mtriple loongarch64-linux-gnu -mattr=+lasx -S | FileCheck %s
 
 ;; This is a collection of tests whose only purpose is to show changes in the
 ;; default configuration.  Please keep these tests minimal - if you're testing