From 75956767b2c172497c553f151e35c5b8d50b524f Mon Sep 17 00:00:00 2001
From: Cheng Shao <terrorjack@type.dance>
Date: Mon, 10 Jun 2024 12:50:23 +0000
Subject: [PATCH] rts: use page sized mblocks on wasm
This patch changes mblock size to page size on wasm. It allows us to
simplify our wasi-libc fork, makes it much easier to test third party
libc allocators like emmalloc/mimalloc, as well as experimenting with
threaded RTS in wasm.
(cherry picked from commit 558353f4e22643b94b9710a45c3364c518d57b46)
(cherry picked from commit f3ea9fb8ed92952941408c39885722e9ed1c2f70)
(cherry picked from commit f747805fcab09336f095c22e632171d1ffc996be)
---
.../tests/T18757.stdout-wasm32-unknown-wasi | 1 +
rts/include/rts/Constants.h | 4 +++
rts/sm/NonMoving.h | 5 ++++
rts/wasm/OSMem.c | 27 ++++++-------------
4 files changed, 18 insertions(+), 19 deletions(-)
create mode 100644 libraries/ghc-compact/tests/T18757.stdout-wasm32-unknown-wasi
diff --git a/libraries/ghc-compact/tests/T18757.stdout-wasm32-unknown-wasi b/libraries/ghc-compact/tests/T18757.stdout-wasm32-unknown-wasi
new file mode 100644
index 00000000000..ca45db43d2a
--- /dev/null
+++ b/libraries/ghc-compact/tests/T18757.stdout-wasm32-unknown-wasi
@@ -0,0 +1 @@
+[61420,61420,61420,60388,60132,60132,60132,60132,60132,60132,60132,60132,60132,60132,60132,60132,60132,60132,60132,60132,60132,60132,60132,60132,60132,60132,60132,60132,60132,60132,60132,60132,60132,60132]
diff --git a/rts/include/rts/Constants.h b/rts/include/rts/Constants.h
index 3bf5a7a2d5a..31e783af3b3 100644
--- a/rts/include/rts/Constants.h
+++ b/rts/include/rts/Constants.h
@@ -170,7 +170,11 @@
#define BLOCK_SHIFT 12
/* The size of a megablock (2^MBLOCK_SHIFT bytes) */
+#if defined(wasm32_HOST_ARCH)
+#define MBLOCK_SHIFT 16
+#else
#define MBLOCK_SHIFT 20
+#endif
/* -----------------------------------------------------------------------------
Bitmap/size fields (used in info tables)
diff --git a/rts/sm/NonMoving.h b/rts/sm/NonMoving.h
index 90763089f68..979b03102c3 100644
--- a/rts/sm/NonMoving.h
+++ b/rts/sm/NonMoving.h
@@ -17,7 +17,12 @@
#include "BeginPrivate.h"
// Segments
+#if defined(wasm32_HOST_ARCH)
+#define NONMOVING_SEGMENT_BITS 14ULL // 2^14 = 16kByte
+#else
#define NONMOVING_SEGMENT_BITS 15ULL // 2^15 = 32kByte
+#endif
+
// Mask to find base of segment
#define NONMOVING_SEGMENT_MASK (((uintptr_t)1 << NONMOVING_SEGMENT_BITS) - 1)
// In bytes
diff --git a/rts/wasm/OSMem.c b/rts/wasm/OSMem.c
index ff4217f413e..d01b3361a0e 100644
--- a/rts/wasm/OSMem.c
+++ b/rts/wasm/OSMem.c
@@ -32,14 +32,8 @@
// libc allocator's certain invariants. But dlmalloc permits this
// behavior!
//
-// Therefore, we bypass dlmalloc, and directly call memory.grow to
-// allocate megablocks. We even patch dlmalloc in the libc sysroot
-// shipped in our wasi-sdk release, so that whenever dlmalloc calls
-// sbrk(), it extends the linear memory to align to the megablock
-// size, so to avoid space waste as much as possible. Our wasi-libc
-// patch doesn't impact ABI interoperability, and when stock clang
-// compiles code that calls malloc() to wasm objects, those objects
-// would just link fine with our build products.
+// Therefore, we bypass dlmalloc, and directly call sbrk() to
+// allocate megablocks.
//
// One remaining question is how to free a megablock. Wasm spec
// doesn't allow shrinking the linear memory, so the logic of
@@ -49,12 +43,13 @@
// megablock on Wasm.
#include "Rts.h"
-
-#include "RtsUtils.h"
#include "sm/OSMem.h"
-#include "rts/storage/HeapAlloc.h"
-#include <__macro_PAGESIZE.h>
+#include <unistd.h>
+
+#define PAGESIZE (0x10000)
+
+GHC_STATIC_ASSERT(MBLOCK_SIZE == PAGESIZE, "MBLOCK_SIZE must be equal to wasm page size");
void osMemInit(void)
{
@@ -63,13 +58,7 @@ void osMemInit(void)
void *
osGetMBlocks(uint32_t n)
{
- size_t base = __builtin_wasm_memory_size(0) * PAGESIZE;
- size_t start = MBLOCK_ROUND_UP(base);
- size_t end = start + (n << MBLOCK_SHIFT);
- ptrdiff_t delta = (end - base) / PAGESIZE;
- if (__builtin_wasm_memory_grow(0, delta) == SIZE_MAX)
- barf("osGetMBlocks failed");
- return start;
+ return sbrk(PAGESIZE * n);
}
void osBindMBlocksToNode(
--
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