From 839ac52e94f8ecf878e522dba0575466af248267 Mon Sep 17 00:00:00 2001
From: Cheng Shao <terrorjack@type.dance>
Date: Thu, 26 Sep 2024 22:30:28 +0000
Subject: [PATCH] ghci: use plain malloc for mkConInfoTable on non-TNTC
platforms
This patch avoids using mmap() to allocate executable memory for
mkConInfoTable on platforms without tables-next-to-code, see added
comment for explanation.
---
libraries/ghci/GHCi/InfoTable.hsc | 14 +++++++++++++-
1 file changed, 13 insertions(+), 1 deletion(-)
diff --git a/libraries/ghci/GHCi/InfoTable.hsc b/libraries/ghci/GHCi/InfoTable.hsc
index 5ac08f693c8..ee6a8b7420c 100644
--- a/libraries/ghci/GHCi/InfoTable.hsc
+++ b/libraries/ghci/GHCi/InfoTable.hsc
@@ -324,7 +324,19 @@ newExecConItbl tables_next_to_code obj con_desc = do
-- with a 32-bit offset relative to the info table, so if we
-- allocated the string separately it might be out of range.
- ex_ptr <- fillExecBuffer (sz + fromIntegral lcon_desc) $ \wr_ptr ex_ptr -> do
+ -- Just use plain malloc on platforms without TNTC, since we
+ -- don't need to allocate executable memory anyway. This is
+ -- much faster than mmap(), and is crucial for wasm since it
+ -- doesn't support mmap() at all, not to mention executable
+ -- memory.
+ fill_exec_buffer = if tables_next_to_code
+ then fillExecBuffer
+ else \n cont -> do
+ p <- mallocBytes $ fromIntegral n
+ cont p p
+ pure p
+
+ ex_ptr <- fill_exec_buffer (sz + fromIntegral lcon_desc) $ \wr_ptr ex_ptr -> do
let cinfo = StgConInfoTable { conDesc = ex_ptr `plusPtr` fromIntegral sz
, infoTable = obj }
pokeConItbl tables_next_to_code wr_ptr ex_ptr cinfo
--
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