[RISCV] Re-separate unaligned scalar and vector memory features in the backend. (#88954)

This is largely a revert of commit
e81796671890b59c110f8e41adc7ca26f8484d20.

As #88029 shows, there exists hardware that only supports unaligned
scalar.

I'm leaving how this gets exposed to the clang interface to a future
patch.

1 files changed, 9 insertions, 4 deletions

diff --git a/llvm/lib/Target/RISCV/RISCVFeatures.td b/llvm/lib/Target/RISCV/RISCVFeatures.td
index 5996221..561187c 100644
--- a/llvm/lib/Target/RISCV/RISCVFeatures.td
+++ b/llvm/lib/Target/RISCV/RISCVFeatures.td
@@ -1183,10 +1183,15 @@ def FeatureTrailingSeqCstFence : SubtargetFeature<"seq-cst-trailing-fence",
                                           "true",
                                           "Enable trailing fence for seq-cst store.">;
 
-def FeatureFastUnalignedAccess
-   : SubtargetFeature<"fast-unaligned-access", "HasFastUnalignedAccess",
-                      "true", "Has reasonably performant unaligned "
-                      "loads and stores (both scalar and vector)">;
+def FeatureUnalignedScalarMem
+   : SubtargetFeature<"unaligned-scalar-mem", "EnableUnalignedScalarMem",
+                      "true", "Has reasonably performant unaligned scalar "
+                      "loads and stores">;
+
+def FeatureUnalignedVectorMem
+   : SubtargetFeature<"unaligned-vector-mem", "EnableUnalignedVectorMem",
+                      "true", "Has reasonably performant unaligned vector "
+                      "loads and stores">;
 
 def FeaturePostRAScheduler : SubtargetFeature<"use-postra-scheduler",
     "UsePostRAScheduler", "true", "Schedule again after register allocation">;