[TableGen] Fix both sides of '&&' are same

The operand of the second any_of in EnforceSmallerThan should be
B not S like the FP code in the if below.

Unfortunately, fixing that causes an infinite loop in the build
of RISCV. So I've added a workaround for that as well.

Fixes PR44768.

Reviewed By: RKSimon

Differential Revision: https://reviews.llvm.org/D111502

1 files changed, 15 insertions, 4 deletions

diff --git a/llvm/utils/TableGen/CodeGenDAGPatterns.cpp b/llvm/utils/TableGen/CodeGenDAGPatterns.cpp
index ebb4a31..2d0694d 100644
--- a/llvm/utils/TableGen/CodeGenDAGPatterns.cpp
+++ b/llvm/utils/TableGen/CodeGenDAGPatterns.cpp
@@ -451,13 +451,16 @@ static Iter max_if(Iter B, Iter E, Pred P, Less L) {
 }
 
 /// Make sure that for each type in Small, there exists a larger type in Big.
-bool TypeInfer::EnforceSmallerThan(TypeSetByHwMode &Small,
-                                   TypeSetByHwMode &Big) {
+bool TypeInfer::EnforceSmallerThan(TypeSetByHwMode &Small, TypeSetByHwMode &Big,
+                                   bool SmallIsVT) {
   ValidateOnExit _1(Small, *this), _2(Big, *this);
   if (TP.hasError())
     return false;
   bool Changed = false;
 
+  assert((!SmallIsVT || !Small.empty()) &&
+         "Small should not be empty for SDTCisVTSmallerThanOp");
+
   if (Small.empty())
     Changed |= EnforceAny(Small);
   if (Big.empty())
@@ -476,7 +479,9 @@ bool TypeInfer::EnforceSmallerThan(TypeSetByHwMode &Small,
     TypeSetByHwMode::SetType &S = Small.get(M);
     TypeSetByHwMode::SetType &B = Big.get(M);
 
-    if (any_of(S, isIntegerOrPtr) && any_of(S, isIntegerOrPtr)) {
+    assert((!SmallIsVT || !S.empty()) && "Expected non-empty type");
+
+    if (any_of(S, isIntegerOrPtr) && any_of(B, isIntegerOrPtr)) {
       auto NotInt = [](MVT VT) { return !isIntegerOrPtr(VT); };
       Changed |= berase_if(S, NotInt);
       Changed |= berase_if(B, NotInt);
@@ -484,6 +489,11 @@ bool TypeInfer::EnforceSmallerThan(TypeSetByHwMode &Small,
       auto NotFP = [](MVT VT) { return !isFloatingPoint(VT); };
       Changed |= berase_if(S, NotFP);
       Changed |= berase_if(B, NotFP);
+    } else if (SmallIsVT && B.empty()) {
+      // B is empty and since S is a specific VT, it will never be empty. Don't
+      // report this as a change, just clear S and continue. This prevents an
+      // infinite loop.
+      S.clear();
     } else if (S.empty() || B.empty()) {
       Changed = !S.empty() || !B.empty();
       S.clear();
@@ -1637,7 +1647,8 @@ bool SDTypeConstraint::ApplyTypeConstraint(TreePatternNode *N,
       getOperandNum(x.SDTCisVTSmallerThanOp_Info.OtherOperandNum, N, NodeInfo,
                     OResNo);
 
-    return TI.EnforceSmallerThan(TypeListTmp, OtherNode->getExtType(OResNo));
+    return TI.EnforceSmallerThan(TypeListTmp, OtherNode->getExtType(OResNo),
+                                 /*SmallIsVT*/ true);
   }
   case SDTCisOpSmallerThanOp: {
     unsigned BResNo = 0;