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[lld][WebAssembly] Allow --no-stack-first in addition to --stack-first #166384

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Merged
merged 2 commits into from
Nov 4, 2025
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[lld][WebAssembly] Allow --no-stack-first in addition to --stack-first #166384

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[lld][WebAssembly] Enable `--no-stack-first` in addition to `--stack-…
sbc100 Nov 4, 2025
8342c26
Update lld/test/wasm/stack-first.test
sbc100 Nov 4, 2025
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25 changes: 25 additions & 0 deletions lld/test/wasm/stack-first.test
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Original file line number Diff line number Diff line change
Expand Up @@ -8,6 +8,15 @@ RUN: llvm-mc -filetype=obj -triple=wasm32-unknown-unknown %p/Inputs/stack-first.
RUN: wasm-ld -z stack-size=512 --stack-first --export=__data_end --export=__heap_base --export=someByte -o %t.wasm %t.o
RUN: obj2yaml %t.wasm | FileCheck %s

; Check `--no-stack-first`
RUN: wasm-ld -z stack-size=512 --stack-first --no-stack-first --export=__data_end --export=__heap_base --export=someByte -o %t.wasm %t.o
RUN: obj2yaml %t.wasm | FileCheck %s --check-prefix=NOT-FIRST

; Check that the default is no-stack-first
RUN: wasm-ld -z stack-size=512 --export=__data_end --export=__heap_base --export=someByte -o %t.wasm %t.o
RUN: obj2yaml %t.wasm | FileCheck %s --check-prefix=NOT-FIRST


CHECK: - Type: GLOBAL
CHECK-NEXT: Globals:
CHECK-NEXT: - Index: 0
Expand Down Expand Up @@ -51,3 +60,19 @@ CHECK-NEXT: Index: 2
CHECK-NEXT: - Name: __heap_base
CHECK-NEXT: Kind: GLOBAL
CHECK-NEXT: Index: 3

NOT-FIRST: - Type: GLOBAL
NOT-FIRST-NEXT: Globals:
NOT-FIRST-NEXT: - Index: 0
NOT-FIRST-NEXT: Type: I32
NOT-FIRST-NEXT: Mutable: true
NOT-FIRST-NEXT: InitExpr:
NOT-FIRST-NEXT: Opcode: I32_CONST
NOT-FIRST-NEXT: Value: 1552
NOT-FIRST-NEXT: - Index: 1
NOT-FIRST-NEXT: Type: I32
NOT-FIRST-NEXT: Mutable: false
NOT-FIRST-NEXT: InitExpr:
NOT-FIRST-NEXT: Opcode: I32_CONST
NOT-FIRST-NEXT: Value: 1024

2 changes: 1 addition & 1 deletion lld/wasm/Driver.cpp
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Expand Up @@ -595,7 +595,7 @@ static void readConfigs(opt::InputArgList &args) {
ctx.arg.shlibSigCheck = !args.hasArg(OPT_no_shlib_sigcheck);
ctx.arg.stripAll = args.hasArg(OPT_strip_all);
ctx.arg.stripDebug = args.hasArg(OPT_strip_debug);
ctx.arg.stackFirst = args.hasArg(OPT_stack_first);
ctx.arg.stackFirst = args.hasFlag(OPT_stack_first, OPT_no_stack_first, false);
ctx.arg.trace = args.hasArg(OPT_trace);
ctx.arg.thinLTOCacheDir = args.getLastArgValue(OPT_thinlto_cache_dir);
ctx.arg.thinLTOCachePolicy = CHECK(
Expand Down
5 changes: 3 additions & 2 deletions lld/wasm/Options.td
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Expand Up @@ -250,8 +250,9 @@ def no_entry: FF<"no-entry">,
def no_shlib_sigcheck: FF<"no-shlib-sigcheck">,
HelpText<"Do not check signatures of functions defined in shared libraries.">;

def stack_first: FF<"stack-first">,
HelpText<"Place stack at start of linear memory rather than after data">;
defm stack_first: B<"stack-first",
"Place stack at start of linear memory",
"Place the stack after static data refion (default)">;
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@bakkot bakkot Nov 4, 2025 •
edited
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Suggested change
"Place the stack after static data refion (default)">;
"Place the stack after static data region (default)">;

(I assume)


def table_base: JJ<"table-base=">,
HelpText<"Table offset at which to place address taken functions (Defaults to 1)">;
Expand Down