Ignore breakpoint for a specified number of iterations. (#19157)

* Implement new debugger command `:ignore` to set an `ignore count`
  for a specified breakpoint.
* Allow new optional parameter on `:continue` command to set an
  `ignore count` for the current breakpoint.

* In the Interpreter replace the current `Word8` BreakArray with
  an `Int` array.
* Change semantics of values in `BreakArray` to:
   n < 0  : Breakpoint is disabled.
   n == 0 : Breakpoint is enabled.
   n > 0  : Breakpoint is enabled, but ignore next `n` iterations.
* Rewrite `:enable`/`:disable` processing as a special case of `:ignore`.
* Remove references to `BreakArray` from `ghc/UI.hs`.

2 files changed, 23 insertions, 6 deletions

diff --git a/compiler/GHC/Runtime/Eval.hs b/compiler/GHC/Runtime/Eval.hs
index fc2f8b8ab3..94a4e775ad 100644
--- a/compiler/GHC/Runtime/Eval.hs
+++ b/compiler/GHC/Runtime/Eval.hs
@@ -23,6 +23,7 @@ module GHC.Runtime.Eval (
         getHistorySpan,
         getModBreaks,
         getHistoryModule,
+        setupBreakpoint,
         back, forward,
         setContext, getContext,
         getNamesInScope,
@@ -397,8 +398,9 @@ handleRunStatus step expr bindings final_ids status history
 #endif
 
 
-resumeExec :: GhcMonad m => (SrcSpan->Bool) -> SingleStep -> m ExecResult
-resumeExec canLogSpan step
+resumeExec :: GhcMonad m => (SrcSpan->Bool) -> SingleStep -> Maybe Int
+           -> m ExecResult
+resumeExec canLogSpan step mbCnt
  = do
    hsc_env <- getSession
    let ic = hsc_IC hsc_env
@@ -433,6 +435,10 @@ resumeExec canLogSpan step
                  , resumeSpan = span
                  , resumeHistory = hist } ->
                withVirtualCWD $ do
+                when (isJust mb_brkpt && isJust mbCnt) $ do
+                  setupBreakpoint hsc_env (fromJust mb_brkpt) (fromJust mbCnt)
+                    -- When the user specified a break ignore count, set it
+                    -- in the interpreter
                 status <- liftIO $ GHCi.resumeStmt hsc_env (isStep step) fhv
                 let prevHistoryLst = fromListBL 50 hist
                     hist' = case mb_brkpt of
@@ -443,6 +449,17 @@ resumeExec canLogSpan step
                                                         fromListBL 50 hist
                 handleRunStatus step expr bindings final_ids status hist'
 
+setupBreakpoint :: GhcMonad m => HscEnv -> BreakInfo -> Int -> m ()   -- #19157
+setupBreakpoint hsc_env brkInfo cnt = do
+  let modl :: Module = breakInfo_module brkInfo
+      breaks hsc_env modl = getModBreaks $ expectJust "setupBreakpoint" $
+         lookupHpt (hsc_HPT hsc_env) (moduleName modl)
+      ix = breakInfo_number brkInfo
+      modBreaks  = breaks hsc_env modl
+      breakarray = modBreaks_flags modBreaks
+  _ <- liftIO $ GHCi.storeBreakpoint hsc_env breakarray ix cnt
+  pure ()
+
 back :: GhcMonad m => Int -> m ([Name], Int, SrcSpan, String)
 back n = moveHist (+n)
 
diff --git a/compiler/GHC/Runtime/Interpreter.hs b/compiler/GHC/Runtime/Interpreter.hs
index cb13089571..cc5f289f48 100644
--- a/compiler/GHC/Runtime/Interpreter.hs
+++ b/compiler/GHC/Runtime/Interpreter.hs
@@ -19,7 +19,7 @@ module GHC.Runtime.Interpreter
   , mkCostCentres
   , costCentreStackInfo
   , newBreakArray
-  , enableBreakpoint
+  , storeBreakpoint
   , breakpointStatus
   , getBreakpointVar
   , getClosure
@@ -379,10 +379,10 @@ newBreakArray hsc_env size = do
   breakArray <- iservCmd hsc_env (NewBreakArray size)
   mkFinalizedHValue hsc_env breakArray
 
-enableBreakpoint :: HscEnv -> ForeignRef BreakArray -> Int -> Bool -> IO ()
-enableBreakpoint hsc_env ref ix b =
+storeBreakpoint :: HscEnv -> ForeignRef BreakArray -> Int -> Int -> IO ()
+storeBreakpoint hsc_env ref ix cnt = do                               -- #19157
   withForeignRef ref $ \breakarray ->
-    iservCmd hsc_env (EnableBreakpoint breakarray ix b)
+    iservCmd hsc_env (SetupBreakpoint breakarray ix cnt)
 
 breakpointStatus :: HscEnv -> ForeignRef BreakArray -> Int -> IO Bool
 breakpointStatus hsc_env ref ix =