[test, LoopVectorize] Fix use of var defined in CHECK-NOT

LLVM test Transforms/LoopVectorize/X86/x86-pr39099.ll tries to check for
the absence of a sequence of instructions with several CHECK-NOT with
one of those directives using a variable defined in another. However
CHECK-NOT are checked independently so that is using a variable defined
in a pattern that should not occur in the input.

This commit only checks for the absence of a widened load which rules
out the presence of the whole sequence and does not involve an undefined
variable.

Reviewed By: fhahn

Differential Revision: https://reviews.llvm.org/D99583

llvm/test/Transforms/LoopVectorize/X86/x86-pr39099.ll

@@ -29,8 +29,7 @@ target datalayout = "e-m:e-p:32:32-f64:32:64-f80:32-n8:16:32-S128"
 ;CHECK-NEXT:  %{{.*}} = shl nuw nsw <8 x i32> %[[VECIND]], <i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1>
 ;CHECK-NEXT:  %[[M:.+]] = extractelement <8 x i1> %[[VMASK]], i32 0
 ;CHECK-NEXT:  br i1 %[[M]], label %pred.load.if, label %pred.load.continue
-;CHECK-NOT:   %[[WIDEVEC:.+]] = load <16 x i8>, <16 x i8>* %{{.*}}, align 1
-;CHECK-NOT:   %{{.*}} = shufflevector <16 x i8> %[[WIDEVEC]], <16 x i8> undef, <8 x i32> <i32 0, i32 2, i32 4, i32 6, i32 8, i32 10, i32 12, i32 14>
+;CHECK-NOT:   %{{.+}} = load <16 x i8>, <16 x i8>* %{{.*}}, align 1
 
 define dso_local void @masked_strided(i8* noalias nocapture readonly %p, i8* noalias nocapture %q, i8 zeroext %guard) local_unnamed_addr {
 entry: