llvm-project/lld/test/wasm/initial-heap.test
Nick Fitzgerald 6018930ef1
[lld][WebAssembly] Support for the custom-page-sizes WebAssembly proposal (#128942)
This commit adds support for WebAssembly's custom-page-sizes proposal to
`wasm-ld`. An overview of the proposal can be found
[here](https://github.com/WebAssembly/custom-page-sizes/blob/main/proposals/custom-page-sizes/Overview.md).
In a sentence, it allows customizing a Wasm memory's page size, enabling
Wasm to target environments with less than 64KiB of memory (the default
Wasm page size) available for Wasm memories.

This commit contains the following:

* Adds a `--page-size=N` CLI flag to `wasm-ld` for configuring the
linked Wasm binary's linear memory's page size.

* When the page size is configured to a non-default value, then the
final Wasm binary will use the encodings defined in the
custom-page-sizes proposal to declare the linear memory's page size.

* Defines a `__wasm_first_page_end` symbol, whose address points to the
first page in the Wasm linear memory, a.k.a. is the Wasm memory's page
size. This allows writing code that is compatible with any page size,
and doesn't require re-compiling its object code. At the same time,
because it just lowers to a constant rather than a memory access or
something, it enables link-time optimization.

* Adds tests for these new features.

r? @sbc100 

cc @sunfishcode
2025-03-04 09:39:30 -08:00

28 lines
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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 aligned to the page size (65536 bytes)
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