Throw an exception on heap overflow

This changes heap overflow to throw a HeapOverflow exception instead of
killing the process.

Test Plan: GHC CI

Reviewers: simonmar, austin, hvr, erikd, bgamari

Reviewed By: simonmar, bgamari

Subscribers: thomie

Differential Revision: https://phabricator.haskell.org/D2790

GHC Trac Issues: #1791

1 files changed, 10 insertions, 0 deletions

diff --git a/includes/rts/Flags.h b/includes/rts/Flags.h
index 62d0800e68..0412415aca 100644
--- a/includes/rts/Flags.h
+++ b/includes/rts/Flags.h
@@ -15,6 +15,10 @@
 #define RTS_FLAGS_H
 
 #include <stdio.h>
+#include <stdint.h>
+#include <stdbool.h>
+#include "stg/Types.h"
+#include "Time.h"
 
 /* For defaults, see the @initRtsFlagsDefaults@ routine. */
 
@@ -71,6 +75,12 @@ typedef struct _GC_FLAGS {
                                  * to handle the exception before we
                                  * raise it again.
                                  */
+    StgWord heapLimitGrace;     /* units: *blocks*
+                                 * After a HeapOverflow exception has
+                                 * been raised, how much extra space is
+                                 * given to the thread to handle the
+                                 * exception before we raise it again.
+                                 */
 
     bool numa;                   /* Use NUMA */
     StgWord numaMask;