[SLP]Fix PR87630: wrong result for externally used vector value.

Need to check that the externally used value can be represented with the
BitWidth before applying it, otherwise need to keep wider type.

Author: alexey-bataev

llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp

@@ -14141,6 +14141,16 @@ bool BoUpSLP::collectValuesToDemote(
       }))
     return FinalAnalysis();
 
+  if (!all_of(I->users(),
+              [=](User *U) {
+                return getTreeEntry(U) ||
+                       (UserIgnoreList && UserIgnoreList->contains(U)) ||
+                       (U->getType()->isSized() &&
+                        DL->getTypeSizeInBits(U->getType()) <= BitWidth);
+              }) &&
+      !IsPotentiallyTruncated(I, BitWidth))
+    return false;
+
   unsigned Start = 0;
   unsigned End = I->getNumOperands();
 

llvm/test/Transforms/SLPVectorizer/X86/external-user-instruction-minbitwidth.ll

@@ -14,17 +14,13 @@ define i8 @test() {
 ; CHECK-NEXT:    [[CONV1:%.*]] = zext i16 [[TMP1]] to i32
 ; CHECK-NEXT:    [[TMP2:%.*]] = insertelement <8 x i32> poison, i32 [[CONV]], i32 0
 ; CHECK-NEXT:    [[TMP3:%.*]] = shufflevector <8 x i32> [[TMP2]], <8 x i32> poison, <8 x i32> zeroinitializer
-; CHECK-NEXT:    [[TMP4:%.*]] = trunc <8 x i32> [[TMP3]] to <8 x i16>
-; CHECK-NEXT:    [[TMP5:%.*]] = or <8 x i16> [[TMP4]], <i16 1, i16 1, i16 1, i16 1, i16 1, i16 1, i16 1, i16 -32767>
+; CHECK-NEXT:    [[TMP4:%.*]] = or <8 x i32> [[TMP3]], <i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 32769>
 ; CHECK-NEXT:    [[TMP6:%.*]] = insertelement <8 x i32> poison, i32 [[CONV1]], i32 0
 ; CHECK-NEXT:    [[TMP7:%.*]] = shufflevector <8 x i32> [[TMP6]], <8 x i32> poison, <8 x i32> zeroinitializer
-; CHECK-NEXT:    [[TMP8:%.*]] = trunc <8 x i32> [[TMP7]] to <8 x i16>
-; CHECK-NEXT:    [[TMP9:%.*]] = add <8 x i16> [[TMP5]], [[TMP8]]
-; CHECK-NEXT:    [[TMP10:%.*]] = call i16 @llvm.vector.reduce.or.v8i16(<8 x i16> [[TMP9]])
-; CHECK-NEXT:    [[TMP11:%.*]] = sext i16 [[TMP10]] to i32
+; CHECK-NEXT:    [[TMP8:%.*]] = add nsw <8 x i32> [[TMP4]], [[TMP7]]
+; CHECK-NEXT:    [[TMP11:%.*]] = call i32 @llvm.vector.reduce.or.v8i32(<8 x i32> [[TMP8]])
 ; CHECK-NEXT:    [[CONV4_30:%.*]] = trunc i32 [[TMP11]] to i8
-; CHECK-NEXT:    [[TMP12:%.*]] = extractelement <8 x i16> [[TMP5]], i32 7
-; CHECK-NEXT:    [[TMP13:%.*]] = sext i16 [[TMP12]] to i32
+; CHECK-NEXT:    [[TMP13:%.*]] = extractelement <8 x i32> [[TMP4]], i32 7
 ; CHECK-NEXT:    [[XOR_31:%.*]] = and i32 [[TMP13]], -2
 ; CHECK-NEXT:    store i32 [[XOR_31]], ptr @d, align 4
 ; CHECK-NEXT:    ret i8 [[CONV4_30]]