adds negative test

Author: SahilPatidar

llvm/test/Transforms/InstCombine/fcmp.ll

@@ -1719,6 +1719,21 @@ define <2 x i1> @fcmp_une_sel_x_negx_with_any_fpzero_nnan_vec(<2 x i1> %cond, <2
   ret <2 x i1> %icmp
 }
 
+; negative test - extra use
+
+define i1 @fcmp_ueq_fsub_const_extra_use(float %x, float %y) {
+; CHECK-LABEL: @fcmp_ueq_fsub_const_extra_use(
+; CHECK-NEXT:    [[FS:%.*]] = fsub float [[X:%.*]], [[Y:%.*]]
+; CHECK-NEXT:    call void @use(float [[FS]])
+; CHECK-NEXT:    [[CMP:%.*]] = fcmp ueq float [[FS]], 0.000000e+00
+; CHECK-NEXT:    ret i1 [[CMP]]
+;
+  %fs = fsub float %x, %y
+  call void @use(float %fs)
+  %cmp = fcmp ueq float %fs, 0.000000e+00
+  ret i1 %cmp
+}
+
 define i1 @fcmp_oeq_fsub_const(float %x, float %y) {
 ; CHECK-LABEL: @fcmp_oeq_fsub_const(
 ; CHECK-NEXT:    [[FS:%.*]] = fsub float [[X:%.*]], [[Y:%.*]]