Add PrimCallConv support to GHCi

This adds support for calling Cmm code from bytecode using the native
calling convention, allowing modules that use `foreign import prim`
to be loaded and debugged in GHCi.

This patch introduces a new `PRIMCALL` bytecode instruction and
a helper stack frame `stg_primcall`. The code is based on the
existing functionality for dealing with unboxed tuples in bytecode,
which has been generalised to handle arbitrary calls.

Fixes #22051

1 files changed, 6 insertions, 0 deletions

diff --git a/rts/Interpreter.c b/rts/Interpreter.c
index 1108ca8ed0..f8885cdbce 100644
--- a/rts/Interpreter.c
+++ b/rts/Interpreter.c
@@ -2038,6 +2038,12 @@ run_BCO:
             goto nextInsn;
         }
 
+        case bci_PRIMCALL: {
+            Sp_subW(1);
+            SpW(0) = (W_)&stg_primcall_info;
+            RETURN_TO_SCHEDULER_NO_PAUSE(ThreadRunGHC, ThreadYielding);
+        }
+
         case bci_CCALL: {
             void *tok;
             int stk_offset            = BCO_NEXT;