[llvm] [RISCV][GISel] Don't custom legalize load/store of vector of pointers if ELEN < XLEN. (PR #101565)

[Craig Topper via llvm-commits]

================
@@ -302,38 +317,28 @@ RISCVLegalizerInfo::RISCVLegalizerInfo(const RISCVSubtarget &ST)
                                                {nxv8s32, p0, nxv8s32, 32},
                                                {nxv16s32, p0, nxv16s32, 32}});
 
-  auto &ExtLoadActions =
-      getActionDefinitionsBuilder({G_SEXTLOAD, G_ZEXTLOAD})
-          .legalForTypesWithMemDesc({{s32, p0, s8, 8}, {s32, p0, s16, 16}});
-  if (XLen == 64) {
-    LoadStoreActions.legalForTypesWithMemDesc({{s64, p0, s8, 8},
-                                               {s64, p0, s16, 16},
-                                               {s64, p0, s32, 32},
-                                               {s64, p0, s64, 64}});
-    ExtLoadActions.legalForTypesWithMemDesc(
-        {{s64, p0, s8, 8}, {s64, p0, s16, 16}, {s64, p0, s32, 32}});
-  } else if (ST.hasStdExtD()) {
-    LoadStoreActions.legalForTypesWithMemDesc({{s64, p0, s64, 64}});
-  }
-  if (ST.hasVInstructions() && ST.getELen() == 64)
-    LoadStoreActions.legalForTypesWithMemDesc({{nxv1s8, p0, nxv1s8, 8},
-                                               {nxv1s16, p0, nxv1s16, 16},
-                                               {nxv1s32, p0, nxv1s32, 32}});
+    if (ST.getELen() == 64)
+      LoadStoreActions.legalForTypesWithMemDesc({{nxv1s8, p0, nxv1s8, 8},
+                                                 {nxv1s16, p0, nxv1s16, 16},
+                                                 {nxv1s32, p0, nxv1s32, 32}});
+
+    if (ST.hasVInstructionsI64())
+      LoadStoreActions.legalForTypesWithMemDesc({{nxv1s64, p0, nxv1s64, 64},
+                                                 {nxv2s64, p0, nxv2s64, 64},
+                                                 {nxv4s64, p0, nxv4s64, 64},
+                                                 {nxv8s64, p0, nxv8s64, 64}});
 
-  if (ST.hasVInstructionsI64())
-    LoadStoreActions.legalForTypesWithMemDesc({{nxv1s64, p0, nxv1s64, 64},
+    // we will take the custom lowering logic if we have scalable vector types
+    // with non-standard alignments
+    LoadStoreActions.customIf(typeIsLegalIntOrFPVec(0, IntOrFPVecTys, ST));
 
-                                               {nxv2s64, p0, nxv2s64, 64},
-                                               {nxv4s64, p0, nxv4s64, 64},
-                                               {nxv8s64, p0, nxv8s64, 64}});
+    // Pointers require that XLen sized elements are legal.
+    if (XLen <= ST.getELen())
+      LoadStoreActions.customIf(typeIsLegalPtrVec(0, PtrVecTys, ST));
----------------
topperc wrote:

> Do we care about FeatureUnalignedVectorMem in the aligned cases? If we were to move the legalIf, it could probably be done in another patch because it doesn't have to do with pointers.

No. But by listing the aligned cases explicitly with legalIf we're effectively hardcoding what allowsMemoryAccessForAlignment is already capable of checking. Is there an advantage to having both a legalIf and a customIf when the customIf can already handle the legal case?

https://github.com/llvm/llvm-project/pull/101565