[CodeGen] Add MVT::isValid to replace manual validity checks. NFC.

Now that we have MVT::FIRST_VALUETYPE (r225362), we can provide a method
checking that the MVT is valid, that is, it's in
  [FIRST_VALUETYPE, LAST_VALUETYPE[.
This commit also uses it in a few asserts, that would previously accept
invalid MVTs, such as the default constructed -1.  In that case,
the code following those asserts would do an out-of-bounds array access.
Using MVT::isValid, those assertions fail as expected when passed
invalid MVTs.
It feels clunky to have such a validity checking function, but it's
at least better than the alternative of broken manual checks.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225411 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/CodeGen/MachineValueType.h

@@ -167,6 +167,12 @@ namespace llvm {
     bool operator>=(const MVT& S) const { return SimpleTy >= S.SimpleTy; }
     bool operator<=(const MVT& S) const { return SimpleTy <= S.SimpleTy; }
 
+    /// isValid - Return true if this is a valid simple valuetype.
+    bool isValid() const {
+      return (SimpleTy >= MVT::FIRST_VALUETYPE &&
+              SimpleTy < MVT::LAST_VALUETYPE);
+    }
+
     /// isFloatingPoint - Return true if this is a FP, or a vector FP type.
     bool isFloatingPoint() const {
       return ((SimpleTy >= MVT::FIRST_FP_VALUETYPE &&

include/llvm/Target/TargetLowering.h

@@ -595,7 +595,7 @@ public:
   /// sequence, or the target has a custom expander for it.
   LegalizeAction
   getIndexedLoadAction(unsigned IdxMode, MVT VT) const {
-    assert(IdxMode < ISD::LAST_INDEXED_MODE && VT < MVT::LAST_VALUETYPE &&
+    assert(IdxMode < ISD::LAST_INDEXED_MODE && VT.isValid() &&
            "Table isn't big enough!");
     unsigned Ty = (unsigned)VT.SimpleTy;
     return (LegalizeAction)((IndexedModeActions[Ty][IdxMode] & 0xf0) >> 4);
@@ -613,7 +613,7 @@ public:
   /// sequence, or the target has a custom expander for it.
   LegalizeAction
   getIndexedStoreAction(unsigned IdxMode, MVT VT) const {
-    assert(IdxMode < ISD::LAST_INDEXED_MODE && VT < MVT::LAST_VALUETYPE &&
+    assert(IdxMode < ISD::LAST_INDEXED_MODE && VT.isValid() &&
            "Table isn't big enough!");
     unsigned Ty = (unsigned)VT.SimpleTy;
     return (LegalizeAction)(IndexedModeActions[Ty][IdxMode] & 0x0f);
@@ -1239,7 +1239,7 @@ protected:
   /// specified type and indicate what to do about it.
   void setLoadExtAction(unsigned ExtType, MVT VT,
                         LegalizeAction Action) {
-    assert(ExtType < ISD::LAST_LOADEXT_TYPE && VT < MVT::LAST_VALUETYPE &&
+    assert(ExtType < ISD::LAST_LOADEXT_TYPE && VT.isValid() &&
            "Table isn't big enough!");
     LoadExtActions[VT.SimpleTy][ExtType] = (uint8_t)Action;
   }
@@ -1248,8 +1248,7 @@ protected:
   /// specified type and indicate what to do about it.
   void setTruncStoreAction(MVT ValVT, MVT MemVT,
                            LegalizeAction Action) {
-    assert(ValVT < MVT::LAST_VALUETYPE && MemVT < MVT::LAST_VALUETYPE &&
-           "Table isn't big enough!");
+    assert(ValVT.isValid() && MemVT.isValid() && "Table isn't big enough!");
     TruncStoreActions[ValVT.SimpleTy][MemVT.SimpleTy] = (uint8_t)Action;
   }
 
@@ -1260,7 +1259,7 @@ protected:
   /// TargetLowering.cpp
   void setIndexedLoadAction(unsigned IdxMode, MVT VT,
                             LegalizeAction Action) {
-    assert(VT < MVT::LAST_VALUETYPE && IdxMode < ISD::LAST_INDEXED_MODE &&
+    assert(VT.isValid() && IdxMode < ISD::LAST_INDEXED_MODE &&
            (unsigned)Action < 0xf && "Table isn't big enough!");
     // Load action are kept in the upper half.
     IndexedModeActions[(unsigned)VT.SimpleTy][IdxMode] &= ~0xf0;
@@ -1274,7 +1273,7 @@ protected:
   /// TargetLowering.cpp
   void setIndexedStoreAction(unsigned IdxMode, MVT VT,
                              LegalizeAction Action) {
-    assert(VT < MVT::LAST_VALUETYPE && IdxMode < ISD::LAST_INDEXED_MODE &&
+    assert(VT.isValid() && IdxMode < ISD::LAST_INDEXED_MODE &&
            (unsigned)Action < 0xf && "Table isn't big enough!");
     // Store action are kept in the lower half.
     IndexedModeActions[(unsigned)VT.SimpleTy][IdxMode] &= ~0x0f;
@@ -1285,8 +1284,7 @@ protected:
   /// target and indicate what to do about it.
   void setCondCodeAction(ISD::CondCode CC, MVT VT,
                          LegalizeAction Action) {
-    assert(VT < MVT::LAST_VALUETYPE &&
-           (unsigned)CC < array_lengthof(CondCodeActions) &&
+    assert(VT.isValid() && (unsigned)CC < array_lengthof(CondCodeActions) &&
            "Table isn't big enough!");
     /// The lower 5 bits of the SimpleTy index into Nth 2bit set from the 32-bit
     /// value and the upper 27 bits index into the second dimension of the array