[SLP]Do not propagate nuw/nsw flags for alt nodes, affected by

minbitwidth analysis.

Need to drop nuw/nsw flags, if the alternate node is resized after the
minbitwidth analysis, to avoid producing poison values in corner cases.

Author: alexey-bataev

llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp

@@ -12621,8 +12621,8 @@ Value *BoUpSLP::vectorizeTree(TreeEntry *E, bool PostponedPHIs) {
           },
           Mask, &OpScalars, &AltScalars);
 
-      propagateIRFlags(V0, OpScalars);
-      propagateIRFlags(V1, AltScalars);
+      propagateIRFlags(V0, OpScalars, E->getMainOp(), !MinBWs.contains(E));
+      propagateIRFlags(V1, AltScalars, E->getAltOp(), !MinBWs.contains(E));
 
       Value *V = Builder.CreateShuffleVector(V0, V1, Mask);
       if (auto *I = dyn_cast<Instruction>(V)) {

llvm/test/Transforms/SLPVectorizer/X86/reorder_diamond_match.ll

@@ -11,11 +11,11 @@ define void @test() {
 ; CHECK-NEXT:    [[TMP6:%.*]] = shl <4 x i16> [[TMP5]], zeroinitializer
 ; CHECK-NEXT:    [[TMP7:%.*]] = add <4 x i16> [[TMP6]], zeroinitializer
 ; CHECK-NEXT:    [[TMP8:%.*]] = shufflevector <4 x i16> [[TMP7]], <4 x i16> poison, <4 x i32> <i32 1, i32 0, i32 3, i32 2>
-; CHECK-NEXT:    [[TMP9:%.*]] = add nsw <4 x i16> [[TMP7]], [[TMP8]]
-; CHECK-NEXT:    [[TMP10:%.*]] = sub nsw <4 x i16> [[TMP7]], [[TMP8]]
+; CHECK-NEXT:    [[TMP9:%.*]] = add <4 x i16> [[TMP7]], [[TMP8]]
+; CHECK-NEXT:    [[TMP10:%.*]] = sub <4 x i16> [[TMP7]], [[TMP8]]
 ; CHECK-NEXT:    [[TMP11:%.*]] = shufflevector <4 x i16> [[TMP9]], <4 x i16> [[TMP10]], <4 x i32> <i32 1, i32 4, i32 3, i32 6>
-; CHECK-NEXT:    [[TMP12:%.*]] = add nsw <4 x i16> zeroinitializer, [[TMP11]]
-; CHECK-NEXT:    [[TMP13:%.*]] = sub nsw <4 x i16> zeroinitializer, [[TMP11]]
+; CHECK-NEXT:    [[TMP12:%.*]] = add <4 x i16> zeroinitializer, [[TMP11]]
+; CHECK-NEXT:    [[TMP13:%.*]] = sub <4 x i16> zeroinitializer, [[TMP11]]
 ; CHECK-NEXT:    [[TMP14:%.*]] = shufflevector <4 x i16> [[TMP12]], <4 x i16> [[TMP13]], <4 x i32> <i32 0, i32 1, i32 6, i32 7>
 ; CHECK-NEXT:    [[TMP15:%.*]] = sext <4 x i16> [[TMP14]] to <4 x i32>
 ; CHECK-NEXT:    store <4 x i32> [[TMP15]], ptr [[TMP2]], align 16