debug: preserve the top of stack when stepping in or at BP (#214902)

Refs  #214433

src/vs/workbench/contrib/debug/common/debugModel.ts

@@ -540,6 +540,8 @@ export class StackFrame implements IStackFrame {
  }
 }
 
+const KEEP_SUBTLE_FRAME_AT_TOP_REASONS: readonly string[] = ['breakpoint', 'step', 'function breakpoint'];
+
 export class Thread implements IThread {
  private callStack: IStackFrame[];
  private staleCallStack: IStackFrame[];
@@ -578,10 +580,11 @@ export class Thread implements IThread {
 
  getTopStackFrame(): IStackFrame | undefined {
  const callStack = this.getCallStack();
+ const stopReason = this.stoppedDetails?.reason;
  // Allow stack frame without source and with instructionReferencePointer as top stack frame when using disassembly view.
  const firstAvailableStackFrame = callStack.find(sf => !!(
- ((this.stoppedDetails?.reason === 'instruction breakpoint' || (this.stoppedDetails?.reason === 'step' && this.lastSteppingGranularity === 'instruction')) && sf.instructionPointerReference) ||
- (sf.source && sf.source.available && !isFrameDeemphasized(sf))));
+ ((stopReason === 'instruction breakpoint' || (stopReason === 'step' && this.lastSteppingGranularity === 'instruction')) && sf.instructionPointerReference) ||
+ (sf.source && sf.source.available && (KEEP_SUBTLE_FRAME_AT_TOP_REASONS.includes(stopReason!) || !isFrameDeemphasized(sf)))));
  return firstAvailableStackFrame;
  }