[llvm] [RISCV][GlobalISel] Legalize Scalable Vector Loads and Stores (PR #84965)

[Michael Maitland via llvm-commits]

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@@ -279,7 +314,29 @@ RISCVLegalizerInfo::RISCVLegalizerInfo(const RISCVSubtarget &ST)
   } else if (ST.hasStdExtD()) {
     LoadStoreActions.legalForTypesWithMemDesc({{s64, p0, s64, 64}});
   }
-  LoadStoreActions.clampScalar(0, s32, sXLen).lower();
+  if (ST.hasVInstructions() && 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}});
+
+  LoadStoreActions.widenScalarToNextPow2(0, /* MinSize = */ 8)
+      .lowerIfMemSizeNotByteSizePow2()
+      .customIf(all(LegalityPredicate([=](const LegalityQuery &Query) {
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michaelmaitland wrote:

nit: IIUC the `customIf` is to handle vector types that have non-standard align arguments. If that is an accurate description, could you add a comment clarifying this point for the reader? If someone isn't familiar with the code, it might not be clear why we are doing this special custom legalization for vector types that we addressed above.

https://github.com/llvm/llvm-project/pull/84965