[SLP]Fix strict weak ordering for Cmp instruction comparator.

Sorting algorithms require strict weak ordering for comparators, final
fix for cmp instructions comparator.

Author: alexey-bataev

llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp

@@ -14697,11 +14697,11 @@ static bool compareCmp(Value *V, Value *V2, TargetLibraryInfo &TLI,
   if (BasePred1 > BasePred2)
     return false;
   // Compare operands.
-  bool LEPreds = Pred1 <= Pred2;
-  bool GEPreds = Pred1 >= Pred2;
+  bool CI1Preds = Pred1 == BasePred1;
+  bool CI2Preds = Pred2 == BasePred1;
   for (int I = 0, E = CI1->getNumOperands(); I < E; ++I) {
-    auto *Op1 = CI1->getOperand(LEPreds ? I : E - I - 1);
-    auto *Op2 = CI2->getOperand(GEPreds ? I : E - I - 1);
+    auto *Op1 = CI1->getOperand(CI1Preds ? I : E - I - 1);
+    auto *Op2 = CI2->getOperand(CI2Preds ? I : E - I - 1);
     if (Op1->getValueID() < Op2->getValueID())
       return !IsCompatibility;
     if (Op1->getValueID() > Op2->getValueID())

llvm/test/Transforms/SLPVectorizer/X86/alternate-cmp-swapped-pred-parent.ll

@@ -8,10 +8,10 @@ define void @test() {
 ; CHECK-NEXT:    br label [[BB:%.*]]
 ; CHECK:       bb:
 ; CHECK-NEXT:    [[CALL:%.*]] = load i16, ptr poison, align 2
-; CHECK-NEXT:    [[TMP0:%.*]] = insertelement <8 x i16> <i16 0, i16 0, i16 0, i16 poison, i16 poison, i16 0, i16 poison, i16 poison>, i16 [[CALL37]], i32 3
-; CHECK-NEXT:    [[TMP1:%.*]] = insertelement <8 x i16> [[TMP0]], i16 [[CALL]], i32 7
-; CHECK-NEXT:    [[TMP2:%.*]] = shufflevector <8 x i16> [[TMP1]], <8 x i16> poison, <8 x i32> <i32 0, i32 1, i32 2, i32 3, i32 3, i32 5, i32 3, i32 7>
-; CHECK-NEXT:    [[TMP3:%.*]] = shufflevector <8 x i16> [[TMP1]], <8 x i16> <i16 0, i16 0, i16 0, i16 0, i16 0, i16 poison, i16 poison, i16 0>, <8 x i32> <i32 8, i32 9, i32 10, i32 11, i32 12, i32 3, i32 7, i32 15>
+; CHECK-NEXT:    [[TMP0:%.*]] = insertelement <8 x i16> <i16 0, i16 0, i16 0, i16 poison, i16 poison, i16 poison, i16 0, i16 poison>, i16 [[CALL37]], i32 3
+; CHECK-NEXT:    [[TMP1:%.*]] = insertelement <8 x i16> [[TMP0]], i16 [[CALL]], i32 5
+; CHECK-NEXT:    [[TMP2:%.*]] = shufflevector <8 x i16> [[TMP1]], <8 x i16> poison, <8 x i32> <i32 0, i32 1, i32 2, i32 3, i32 3, i32 5, i32 6, i32 3>
+; CHECK-NEXT:    [[TMP3:%.*]] = shufflevector <8 x i16> [[TMP1]], <8 x i16> <i16 0, i16 0, i16 0, i16 0, i16 0, i16 0, i16 poison, i16 poison>, <8 x i32> <i32 8, i32 9, i32 10, i32 11, i32 12, i32 13, i32 3, i32 5>
 ; CHECK-NEXT:    [[TMP4:%.*]] = icmp slt <8 x i16> [[TMP2]], [[TMP3]]
 ; CHECK-NEXT:    ret void
 ;