Magic-Mirror/llvm-capstone
1
0
Fork 0
mirror of https://github.com/capstone-engine/llvm-capstone.git synced 2025-04-12 03:10:03 +00:00
Code Issues Actions 2 Packages Projects Releases Wiki Activity

[lld][WebAssembly] Add an --initial-heap option (#75594)

Browse Source 
It is beneficial to preallocate a certain number of pages in the linear
memory (i. e. use the "minimum" field of WASM memories) so that fewer
"memory.grow"s are needed at startup.

So far, the way to do that has been to pass the "--initial-memory"
option to the linker. It works, but has the very significant downside of
requiring the user to know the size of static data beforehand, as it
must not exceed the number of bytes passed-in as "--initial-memory".

The new "--initial-heap" option avoids this downside by simply appending
the specified number of pages to static data (and stack), regardless of
how large they already are.

Ref: https://github.com/emscripten-core/emscripten/issues/20888.
This commit is contained in:
SingleAccretion 2023-12-15 21:16:38 +03:00 committed by GitHub
parent 1709e8c656
commit b2cdf3cc4c
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
6 changed files with 49 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
lld/docs/WebAssembly.rst
View File

@ -123,9 +123,13 @@ WebAssembly-specific options:
is not possible for undefined data symbols. Undefined data symbols will
still be reported as normal (in accordance with ``--unresolved-symbols``).
.. option:: --initial-heap=<value>
Initial size of the heap. Default: zero.
.. option:: --initial-memory=<value>
Initial size of the linear memory. Default: static data size.
Initial size of the linear memory. Default: the sum of stack, static data and heap sizes.
.. option:: --max-memory=<value>

27
lld/test/wasm/initial-heap.test Normal file
View File

@ -0,0 +1,27 @@
RUN: llvm-mc -filetype=obj -triple=wasm32-unknown-unknown %p/Inputs/start.s -o %t.o
; The initial heap size will be added to the stack size
RUN: wasm-ld %t.o -o %t1.wasm --stack-first -z stack-size=65536 --initial-heap=131072
RUN: obj2yaml %t1.wasm | FileCheck %s --check-prefixes=CHECK,CHECK-2P
; Also test that we can parse and process a large size correctly
RUN: wasm-ld %t.o -o %t2.wasm --stack-first -z stack-size=65536 --initial-heap=4294901760
RUN: obj2yaml %t2.wasm | FileCheck %s --check-prefixes=CHECK,CHECK-4G
CHECK: - Type: MEMORY
CHECK-NEXT: Memories:
CHECK-2P-NEXT: Minimum: 0x3
CHECK-4G-NEXT: Minimum: 0x10000
; Test various error cases.
RUN: not wasm-ld %t.o -o %t3.wasm --initial-heap=131073 2>&1 | FileCheck %s --check-prefix NOT-PAGE-MULTIPLE
RUN: not wasm-ld %t.o -o %t4.wasm --stack-first -z stack-size=65536 --initial-heap=4295032832 2>&1 | FileCheck %s --check-prefix TOO-LARGE-BY-ITSELF
RUN: not wasm-ld %t.o -o %t5.wasm --stack-first -z stack-size=131072 --initial-heap=4294901760 2>&1 | FileCheck %s --check-prefix TOO-LARGE-WITH-STACK
RUN: not wasm-ld %t.o -o %t6.wasm --stack-first -z stack-size=65536 --initial-heap=131072 --initial-memory=131072 2>&1 | FileCheck %s --check-prefix INITIAL-MEMORY-TOO-SMALL
RUN: not wasm-ld %t.o -o %t7.wasm --stack-first -z stack-size=65536 --initial-heap=131072 --max-memory=131072 2>&1 | FileCheck %s --check-prefix MAX-MEMORY-TOO-SMALL
NOT-PAGE-MULTIPLE: initial heap must be 65536-byte aligned
TOO-LARGE-BY-ITSELF: initial heap too large, cannot be greater than 4294901760
TOO-LARGE-WITH-STACK: initial heap too large, cannot be greater than 4294836224
INITIAL-MEMORY-TOO-SMALL: initial memory too small, 196608 bytes needed
MAX-MEMORY-TOO-SMALL: maximum memory too small, 196608 bytes needed

1
lld/wasm/Config.h
View File

@ -68,6 +68,7 @@ struct Configuration {
bool isStatic = false;
bool trace;
uint64_t globalBase;
uint64_t initialHeap;
uint64_t initialMemory;
uint64_t maxMemory;
uint64_t zStackSize;

5
lld/wasm/Driver.cpp
View File

@ -502,9 +502,10 @@ static void readConfigs(opt::InputArgList &args) {
errorHandler().verbose = args.hasArg(OPT_verbose);
LLVM_DEBUG(errorHandler().verbose = true);
config->initialMemory = args::getInteger(args, OPT_initial_memory, 0);
config->globalBase = args::getInteger(args, OPT_global_base, 0);
config->tableBase = args::getInteger(args, OPT_table_base, 0);
config->globalBase = args::getInteger(args, OPT_global_base, 0);
config->initialHeap = args::getInteger(args, OPT_initial_heap, 0);
config->initialMemory = args::getInteger(args, OPT_initial_memory, 0);
config->maxMemory = args::getInteger(args, OPT_max_memory, 0);
config->zStackSize =
args::getZOptionValue(args, OPT_z, "stack-size", WasmPageSize);

3
lld/wasm/Options.td
View File

@ -215,6 +215,9 @@ defm soname: Eq<"soname", "Set the module name in the generated name section">;
def import_table: FF<"import-table">,
HelpText<"Import function table from the environment">;
def initial_heap: JJ<"initial-heap=">,
HelpText<"Initial size of the heap">;
def initial_memory: JJ<"initial-memory=">,
HelpText<"Initial size of the linear memory">;

10
lld/wasm/Writer.cpp
View File

@ -439,6 +439,16 @@ void Writer::layoutMemory() {
maxMemorySetting = 1ULL << 34;
}
if (config->initialHeap != 0) {
if (config->initialHeap != alignTo(config->initialHeap, WasmPageSize))
error("initial heap must be " + Twine(WasmPageSize) + "-byte aligned");
uint64_t maxInitialHeap = maxMemorySetting - memoryPtr;
if (config->initialHeap > maxInitialHeap)
error("initial heap too large, cannot be greater than " +
Twine(maxInitialHeap));
memoryPtr += config->initialHeap;
}
if (config->initialMemory != 0) {
if (config->initialMemory != alignTo(config->initialMemory, WasmPageSize))
error("initial memory must be " + Twine(WasmPageSize) + "-byte aligned");