GHCi: use non-updatable thunks for breakpoints

The extra safe points introduced for breakpoints were previously
compiled as normal updatable thunks, but they are guaranteed
single-entry, so we can use non-updatable thunks here.  This restores
the tail-call property where it was lost in some cases (although stack
squeezing probably often recovered it), and should improve
performance.

1 files changed, 12 insertions, 1 deletions

diff --git a/rts/Interpreter.c b/rts/Interpreter.c
index 527ebde0d0..00830f43f2 100644
--- a/rts/Interpreter.c
+++ b/rts/Interpreter.c
@@ -1049,6 +1049,17 @@ run_BCO:
 	    goto nextInsn;
 	}
 
+	case bci_ALLOC_AP_NOUPD: {
+	    StgAP* ap; 
+	    int n_payload = BCO_NEXT;
+	    ap = (StgAP*)allocate(AP_sizeW(n_payload));
+	    Sp[-1] = (W_)ap;
+	    ap->n_args = n_payload;
+	    SET_HDR(ap, &stg_AP_NOUPD_info, CCS_SYSTEM/*ToDo*/)
+	    Sp --;
+	    goto nextInsn;
+	}
+
 	case bci_ALLOC_PAP: {
 	    StgPAP* pap; 
 	    int arity = BCO_NEXT;
@@ -1370,7 +1381,7 @@ run_BCO:
 	    // Errors
 	default: 
 	    barf("interpretBCO: unknown or unimplemented opcode %d",
-                 (int)BCO_NEXT);
+                 (int)(bci & 0xFF));
 
 	} /* switch on opcode */
     }