To add a bit to the above. Around 1950 when the single seat Vampire FB 30 was introduced into the RAAF, RR Nene engines replaced the standard RR Goblin engine. These were the Vampire Mk 30 aircraft I flew. Two engine air intakes for the Nene were installed on the fuselage either side and behind of the cockpit. Unfortunately, high speed dive tests were not conducted otherwise the dangerous situation that led to the deaths of several Vampire pilots would have been detected.
It was discovered that at Mach numbers exceeding about 0.73, shock waves began to form over the curved surfaces of the air intakes behind the cockpit and in turn these caused loss of elevator effectiveness and the aircraft would pitch into a steep dive. It was called compressibility. The first crash occurred when two Vampires were practicing formation loops around 15,000 ft where the technique was to select air brakes out at the top of the loop to minimise speed build up in the recovery dive. The leader for some reason omitted to select his airbrakes out and got into compressibility (lack of elevator effectiveness). Thus he went into a high speed dive which went beyond the vertical. With no ejection seat fitted to the Mk 30 Vampire, the pilot was unable to abandon his aircraft by parachute.
The second Vampire pilot retracted his own speed brakes in an attempt to keep up with his leader and he suffered the same fate. Both pilots reported over the radio they were in compressibility.
Later another Vampire crashed when the pilot was conducting a practice diving attack and went straight in. The De Havilland (Bankstown) test pilot "Black Jack" Walker was directed to test a similar Vampire and he deliberately rolled inverted at 40,000 ft and dived to see what was happening. He reported complete loss of elevator effectiveness and was vertical until he was able to recover by 1500 ft. Following his test flight, it was thought the problem was in the shock waves on the upper fuselage air intakes. The aircraft was modified to place the air intakes underneath the fuselage and the problem went away. Meanwhile ejection seats were added and the Vampire became the Mark 31. We used to delight in diving the Mk 31 and instead of tucking under on reaching critical Mach it would suddenly pitch up - which was indeed Good Thing!
So although the reaching of the critical Mach caused loss of elevator effectiveness in the Mk 30 it surely could not be termed a "high speed stall" So whether a Boeing 737 reaching the high speed "clacker" Mach Number is called a high speed stall when there is no loss of control as it is popularly known, I still have difficulty understanding the "stall" reference as against loss of control, as in the early Vampires that crashed un-stalled at very high speeds..