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Merge pull request #5440 from kubkon/align-fn-error-wasm

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Make align expr on fns a compile error in Wasm
This commit is contained in:
Andrew Kelley 2020-05-26 15:49:19 -04:00 committed by GitHub
commit ef42ef9ce8
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3 changed files with 44 additions and 4 deletions
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15
src/analyze.cpp
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@ -1921,6 +1921,21 @@ static ZigType *analyze_fn_type(CodeGen *g, AstNode *proto_node, Scope *child_sc
}
if (fn_proto->align_expr != nullptr) {
if (target_is_wasm(g->zig_target)) {
// In Wasm, specifying alignment of function pointers makes little sense
// since function pointers are in fact indices to a Wasm table, therefore
// any alignment check on those is invalid. This can cause unexpected
// behaviour when checking expected alignment with `@ptrToInt(fn_ptr)`
// or similar. This commit proposes to make `align` expressions a
// compile error when compiled to Wasm architecture.
//
// Some references:
// [1] [Mozilla: WebAssembly Tables](https://developer.mozilla.org/en-US/docs/WebAssembly/Understanding_the_text_format#WebAssembly_tables)
// [2] [Sunfishcode's Wasm Ref Manual](https://github.com/sunfishcode/wasm-reference-manual/blob/master/WebAssembly.md#indirect-call)
add_node_error(g, fn_proto->align_expr,
buf_sprintf("align(N) expr is not allowed on function prototypes in wasm32/wasm64"));
return g->builtin_types.entry_invalid;
}
if (!analyze_const_align(g, child_scope, fn_proto->align_expr, &fn_type_id.alignment)) {
return g->builtin_types.entry_invalid;
}

16
test/compile_errors.zig
View File

@ -7445,4 +7445,20 @@ pub fn addCases(cases: *tests.CompileErrorContext) void {
, &[_][]const u8{
":2:75: error: operation caused overflow",
});
cases.addCase(x: {
var tc = cases.create("align(N) expr function pointers is a compile error",
\\export fn foo() align(1) void {
\\ return;
\\}
, &[_][]const u8{
"tmp.zig:1:23: error: align(N) expr is not allowed on function prototypes in wasm32/wasm64",
});
tc.target = std.zig.CrossTarget{
.cpu_arch = .wasm32,
.os_tag = .freestanding,
.abi = .none,
};
break :x tc;
});
}

17
test/stage1/behavior/align.zig
View File

@ -25,6 +25,9 @@ fn noop1() align(1) void {}
fn noop4() align(4) void {}
test "function alignment" {
// function alignment is a compile error on wasm32/wasm64
if (builtin.arch == .wasm32 or builtin.arch == .wasm64) return error.SkipZigTest;
expect(derp() == 1234);
expect(@TypeOf(noop1) == fn () align(1) void);
expect(@TypeOf(noop4) == fn () align(4) void);
@ -117,6 +120,9 @@ fn sliceExpects4(slice: []align(4) u32) void {
}
test "implicitly decreasing fn alignment" {
// function alignment is a compile error on wasm32/wasm64
if (builtin.arch == .wasm32 or builtin.arch == .wasm64) return error.SkipZigTest;
testImplicitlyDecreaseFnAlign(alignedSmall, 1234);
testImplicitlyDecreaseFnAlign(alignedBig, 5678);
}
@ -133,8 +139,8 @@ fn alignedBig() align(16) i32 {
}
test "@alignCast functions" {
// TODO investigate why this fails when cross-compiled to wasm.
if (builtin.os.tag == .wasi) return error.SkipZigTest;
// function alignment is a compile error on wasm32/wasm64
if (builtin.arch == .wasm32 or builtin.arch == .wasm64) return error.SkipZigTest;
expect(fnExpectsOnly1(simple4) == 0x19);
}
@ -149,6 +155,9 @@ fn simple4() align(4) i32 {
}
test "generic function with align param" {
// function alignment is a compile error on wasm32/wasm64
if (builtin.arch == .wasm32 or builtin.arch == .wasm64) return error.SkipZigTest;
expect(whyWouldYouEverDoThis(1) == 0x1);
expect(whyWouldYouEverDoThis(4) == 0x1);
expect(whyWouldYouEverDoThis(8) == 0x1);
@ -327,8 +336,8 @@ test "align(@alignOf(T)) T does not force resolution of T" {
}
test "align(N) on functions" {
// TODO investigate why this fails when cross-compiled to wasm.
if (builtin.os.tag == .wasi) return error.SkipZigTest;
// function alignment is a compile error on wasm32/wasm64
if (builtin.arch == .wasm32 or builtin.arch == .wasm64) return error.SkipZigTest;
expect((@ptrToInt(overaligned_fn) & (0x1000 - 1)) == 0);
}