codeGen: Introduce flag to bounds-check array accesses

Here we introduce code generator support for instrument array primops
with bounds checking, enabled with the `-fcheck-prim-bounds` flag.

Introduced to debug #20769.

1 files changed, 12 insertions, 0 deletions

diff --git a/docs/users_guide/debugging.rst b/docs/users_guide/debugging.rst
index 569923ade4..77bb7f0e2c 100644
--- a/docs/users_guide/debugging.rst
+++ b/docs/users_guide/debugging.rst
@@ -999,6 +999,18 @@ Checking for consistency
     cases. This is helpful when debugging demand analysis or type checker bugs
     which can sometimes manifest as segmentation faults.
 
+.. ghc-flag:: -fcheck-prim-bounds
+    :shortdesc: Instrument array primops with bounds checks.
+    :type: dynamic
+
+    Typically primops operations like ``writeArray#`` exhibit unsafe behavior,
+    relying on the user to perform any bounds checking. This flag instructs the
+    code generator to instrument such operations with bound checking logic
+    which aborts the program when an out-of-bounds access is detected.
+
+    Note that this is only intended to be used as a debugging measure, not as
+    the primary means of catching out-of-bounds accesses.
+
 .. _checking-determinism:
 
 Checking for determinism