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LLVM: fix extern functions missing attributes

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Extern functions were missing attributes such as "readonly" on
non-optional pointers, and "byval" which is required to match C ABI.

Follow-up from bf28765a975355c27558eaa86cf00ccb29b663a7.

closes #12683
This commit is contained in:
Andrew Kelley 2022-08-30 14:45:03 -07:00
parent 1e21876de2
commit fb81ba8762
2 changed files with 92 additions and 36 deletions
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126
src/codegen/llvm.zig
View File

@ -910,10 +910,11 @@ pub const Object = struct {
while (it.next()) |lowering| switch (lowering) {
.no_bits => continue,
.byval => {
const param_ty = fn_info.param_types[it.zig_index - 1];
assert(!it.byval_attr);
const param_index = it.zig_index - 1;
const param_ty = fn_info.param_types[param_index];
const param = llvm_func.getParam(llvm_arg_i);
try args.ensureUnusedCapacity(1);
assert(!it.byval_attr);
if (isByRef(param_ty)) {
const alignment = param_ty.abiAlignment(target);
@ -926,32 +927,7 @@ pub const Object = struct {
} else {
args.appendAssumeCapacity(param);
if (param_ty.isPtrAtRuntime()) {
const ptr_info = param_ty.ptrInfo().data;
if (math.cast(u5, it.zig_index - 1)) |i| {
if (@truncate(u1, fn_info.noalias_bits >> i) != 0) {
dg.addArgAttr(llvm_func, llvm_arg_i, "noalias");
}
}
if (!param_ty.isPtrLikeOptional() and !ptr_info.@"allowzero") {
dg.addArgAttr(llvm_func, llvm_arg_i, "nonnull");
}
if (!ptr_info.mutable) {
dg.addArgAttr(llvm_func, llvm_arg_i, "readonly");
}
if (ptr_info.@"align" != 0) {
dg.addArgAttrInt(llvm_func, llvm_arg_i, "align", ptr_info.@"align");
} else {
const elem_align = @maximum(
ptr_info.pointee_type.abiAlignment(target),
1,
);
dg.addArgAttrInt(llvm_func, llvm_arg_i, "align", elem_align);
}
} else if (ccAbiPromoteInt(fn_info.cc, target, param_ty)) |s| switch (s) {
.signed => dg.addArgAttr(llvm_func, llvm_arg_i, "signext"),
.unsigned => dg.addArgAttr(llvm_func, llvm_arg_i, "zeroext"),
};
dg.addByValParamAttrs(llvm_func, param_ty, param_index, fn_info, llvm_arg_i);
}
llvm_arg_i += 1;
},
@ -961,13 +937,7 @@ pub const Object = struct {
const param = llvm_func.getParam(llvm_arg_i);
const alignment = param_ty.abiAlignment(target);
dg.addArgAttr(llvm_func, llvm_arg_i, "nonnull");
dg.addArgAttr(llvm_func, llvm_arg_i, "readonly");
dg.addArgAttrInt(llvm_func, llvm_arg_i, "align", alignment);
if (it.byval_attr) {
llvm_func.addByValAttr(llvm_arg_i, param_llvm_ty);
}
dg.addByRefParamAttrs(llvm_func, llvm_arg_i, alignment, it.byval_attr, param_llvm_ty);
llvm_arg_i += 1;
try args.ensureUnusedCapacity(1);
@ -2531,6 +2501,39 @@ pub const DeclGen = struct {
dg.addFnAttr(llvm_fn, "noreturn");
}
// Add parameter attributes. We handle only the case of extern functions (no body)
// because functions with bodies are handled in `updateFunc`.
if (is_extern) {
var it = iterateParamTypes(dg, fn_info);
it.llvm_index += @boolToInt(sret);
it.llvm_index += @boolToInt(err_return_tracing);
while (it.next()) |lowering| switch (lowering) {
.byval => {
const param_index = it.zig_index - 1;
const param_ty = fn_info.param_types[param_index];
if (!isByRef(param_ty)) {
dg.addByValParamAttrs(llvm_fn, param_ty, param_index, fn_info, it.llvm_index - 1);
}
},
.byref => {
const param_ty = fn_info.param_types[it.zig_index - 1];
const param_llvm_ty = try dg.lowerType(param_ty);
const alignment = param_ty.abiAlignment(target);
dg.addByRefParamAttrs(llvm_fn, it.llvm_index - 1, alignment, it.byval_attr, param_llvm_ty);
},
// No attributes needed for these.
.no_bits,
.abi_sized_int,
.multiple_llvm_ints,
.multiple_llvm_float,
.as_u16,
=> continue,
.slice => unreachable, // extern functions do not support slice types.
};
}
return llvm_fn;
}
@ -4141,6 +4144,59 @@ pub const DeclGen = struct {
return null;
}
}
fn addByValParamAttrs(
dg: DeclGen,
llvm_fn: *const llvm.Value,
param_ty: Type,
param_index: u32,
fn_info: Type.Payload.Function.Data,
llvm_arg_i: u32,
) void {
const target = dg.module.getTarget();
if (param_ty.isPtrAtRuntime()) {
const ptr_info = param_ty.ptrInfo().data;
if (math.cast(u5, param_index)) |i| {
if (@truncate(u1, fn_info.noalias_bits >> i) != 0) {
dg.addArgAttr(llvm_fn, llvm_arg_i, "noalias");
}
}
if (!param_ty.isPtrLikeOptional() and !ptr_info.@"allowzero") {
dg.addArgAttr(llvm_fn, llvm_arg_i, "nonnull");
}
if (!ptr_info.mutable) {
dg.addArgAttr(llvm_fn, llvm_arg_i, "readonly");
}
if (ptr_info.@"align" != 0) {
dg.addArgAttrInt(llvm_fn, llvm_arg_i, "align", ptr_info.@"align");
} else {
const elem_align = @maximum(
ptr_info.pointee_type.abiAlignment(target),
1,
);
dg.addArgAttrInt(llvm_fn, llvm_arg_i, "align", elem_align);
}
} else if (ccAbiPromoteInt(fn_info.cc, target, param_ty)) |s| switch (s) {
.signed => dg.addArgAttr(llvm_fn, llvm_arg_i, "signext"),
.unsigned => dg.addArgAttr(llvm_fn, llvm_arg_i, "zeroext"),
};
}
fn addByRefParamAttrs(
dg: DeclGen,
llvm_fn: *const llvm.Value,
llvm_arg_i: u32,
alignment: u32,
byval_attr: bool,
param_llvm_ty: *const llvm.Type,
) void {
dg.addArgAttr(llvm_fn, llvm_arg_i, "nonnull");
dg.addArgAttr(llvm_fn, llvm_arg_i, "readonly");
dg.addArgAttrInt(llvm_fn, llvm_arg_i, "align", alignment);
if (byval_attr) {
llvm_fn.addByValAttr(llvm_arg_i, param_llvm_ty);
}
}
};
pub const FuncGen = struct {

2
test/standalone.zig
View File

@ -44,7 +44,7 @@ pub fn addCases(cases: *tests.StandaloneContext) void {
}
// C ABI compatibility issue: https://github.com/ziglang/zig/issues/1481
if (builtin.cpu.arch == .x86_64) {
if (builtin.zig_backend == .stage1 or builtin.zig_backend == .stage2_llvm) { // https://github.com/ziglang/zig/issues/12222
if (builtin.zig_backend == .stage1 or builtin.zig_backend == .stage2_llvm) {
cases.addBuildFile("test/c_abi/build.zig", .{});
}
}