[DAGCombiner] Precommit test case for D95086

This is the test case for D95086 with worse result.

Differential Revision: https://reviews.llvm.org/D95103

llvm/test/CodeGen/X86/select-ext.ll

@@ -0,0 +1,21 @@
+; RUN: llc -mtriple=x86_64-unknown-unknown < %s | FileCheck %s
+
+; TODO: (zext(select c, load1, load2)) -> (select c, zextload1, zextload2)
+
+; CHECK-LABEL: foo
+; CHECK:        movzbl  (%rdi), %eax
+; CHECK-NEXT:   movzbl  1(%rdi), %ecx
+; CHECK-NEXT:   testl   %esi, %esi
+; CHECK-NEXT:   cmovel  %eax, %ecx
+; CHECK-NEXT:   movzbl  %cl, %eax
+; CHECK-NEXT:   retq
+
+define i64 @foo(i8* %p, i1 zeroext %c) {
+  %ld1 = load volatile i8, i8* %p
+  %arrayidx1 = getelementptr inbounds i8, i8* %p, i64 1
+  %ld2 = load volatile i8, i8* %arrayidx1
+  %cond.v = select i1 %c, i8 %ld2, i8 %ld1
+  %cond = zext i8 %cond.v to i64
+  ret i64 %cond
+}
+