[RISCV] Expand scalable-vector truncstores and extloads

Caught in internal testing, these operations are assumed legal by
default, even for scalable vector types. Expand them back into separate
truncations and stores, or loads and extensions.

Also add explicit fixed-length vector tests for these operations, even
though they should have been correct already.

Reviewed By: craig.topper

Differential Revision: https://reviews.llvm.org/D99654

llvm/lib/Target/RISCV/RISCVISelLowering.cpp

@@ -440,6 +440,15 @@ RISCVTargetLowering::RISCVTargetLowering(const TargetMachine &TM,
       setOperationAction(ISD::EXTRACT_SUBVECTOR, VT, Custom);
 
       setOperationAction(ISD::EXTRACT_VECTOR_ELT, VT, Custom);
+
+      // Expand all extending loads to types larger than this, and truncating
+      // stores from types larger than this.
+      for (MVT OtherVT : MVT::integer_scalable_vector_valuetypes()) {
+        setTruncStoreAction(OtherVT, VT, Expand);
+        setLoadExtAction(ISD::EXTLOAD, OtherVT, VT, Expand);
+        setLoadExtAction(ISD::SEXTLOAD, OtherVT, VT, Expand);
+        setLoadExtAction(ISD::ZEXTLOAD, OtherVT, VT, Expand);
+      }
     }
 
     for (MVT VT : IntVecVTs) {
@@ -498,6 +507,13 @@ RISCVTargetLowering::RISCVTargetLowering(const TargetMachine &TM,
 
       setOperationAction(ISD::STEP_VECTOR, VT, Custom);
       setOperationAction(ISD::VECTOR_REVERSE, VT, Custom);
+
+      for (MVT OtherVT : MVT::integer_scalable_vector_valuetypes()) {
+        setTruncStoreAction(VT, OtherVT, Expand);
+        setLoadExtAction(ISD::EXTLOAD, OtherVT, VT, Expand);
+        setLoadExtAction(ISD::SEXTLOAD, OtherVT, VT, Expand);
+        setLoadExtAction(ISD::ZEXTLOAD, OtherVT, VT, Expand);
+      }
     }
 
     // Expand various CCs to best match the RVV ISA, which natively supports UNE
@@ -545,17 +561,32 @@ RISCVTargetLowering::RISCVTargetLowering(const TargetMachine &TM,
       setOperationAction(ISD::VECTOR_REVERSE, VT, Custom);
     };
 
+    // Sets common extload/truncstore actions on RVV floating-point vector
+    // types.
+    const auto SetCommonVFPExtLoadTruncStoreActions =
+        [&](MVT VT, ArrayRef<MVT::SimpleValueType> SmallerVTs) {
+          for (auto SmallVT : SmallerVTs) {
+            setTruncStoreAction(VT, SmallVT, Expand);
+            setLoadExtAction(ISD::EXTLOAD, VT, SmallVT, Expand);
+          }
+        };
+
     if (Subtarget.hasStdExtZfh())
       for (MVT VT : F16VecVTs)
         SetCommonVFPActions(VT);
 
-    if (Subtarget.hasStdExtF())
-      for (MVT VT : F32VecVTs)
+    for (MVT VT : F32VecVTs) {
+      if (Subtarget.hasStdExtF())
         SetCommonVFPActions(VT);
+      SetCommonVFPExtLoadTruncStoreActions(VT, F16VecVTs);
+    }
 
-    if (Subtarget.hasStdExtD())
-      for (MVT VT : F64VecVTs)
+    for (MVT VT : F64VecVTs) {
+      if (Subtarget.hasStdExtD())
         SetCommonVFPActions(VT);
+      SetCommonVFPExtLoadTruncStoreActions(VT, F16VecVTs);
+      SetCommonVFPExtLoadTruncStoreActions(VT, F32VecVTs);
+    }
 
     if (Subtarget.useRVVForFixedLengthVectors()) {
       for (MVT VT : MVT::integer_fixedlen_vector_valuetypes()) {
@@ -565,8 +596,12 @@ RISCVTargetLowering::RISCVTargetLowering(const TargetMachine &TM,
         // By default everything must be expanded.
         for (unsigned Op = 0; Op < ISD::BUILTIN_OP_END; ++Op)
           setOperationAction(Op, VT, Expand);
-        for (MVT OtherVT : MVT::fixedlen_vector_valuetypes())
+        for (MVT OtherVT : MVT::integer_fixedlen_vector_valuetypes()) {
           setTruncStoreAction(VT, OtherVT, Expand);
+          setLoadExtAction(ISD::EXTLOAD, OtherVT, VT, Expand);
+          setLoadExtAction(ISD::SEXTLOAD, OtherVT, VT, Expand);
+          setLoadExtAction(ISD::ZEXTLOAD, OtherVT, VT, Expand);
+        }
 
         // We use EXTRACT_SUBVECTOR as a "cast" from scalable to fixed.
         setOperationAction(ISD::INSERT_SUBVECTOR, VT, Custom);