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LLVM: use @llvm.used instead of @llvm.compiler.used

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because it marks the linker section, preventing garbage collection.

Also, name the members because that is required by this intrinsic.

Also, enable the StackDepth option in the sancov pass as a workaround
for https://github.com/llvm/llvm-project/pull/106464, otherwise, LLVM
enables TracePCGuard even though we explicitly disable it.
This commit is contained in:
Andrew Kelley 2024-08-28 16:57:43 -07:00
parent 9e11c4f60e
commit c81219c573
1 changed files with 17 additions and 15 deletions
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32
src/codegen/llvm.zig
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@ -822,8 +822,8 @@ pub const Object = struct {
/// This is denormalized data.
struct_field_map: std.AutoHashMapUnmanaged(ZigStructField, c_uint),
/// Values for `@llvm.compiler.used`.
compiler_used: std.ArrayListUnmanaged(Builder.Constant),
/// Values for `@llvm.used`.
used: std.ArrayListUnmanaged(Builder.Constant),
const ZigStructField = struct {
struct_ty: InternPool.Index,
@ -978,7 +978,7 @@ pub const Object = struct {
.error_name_table = .none,
.null_opt_usize = .no_init,
.struct_field_map = .{},
.compiler_used = .{},
.used = .{},
};
return obj;
}
@ -1110,11 +1110,11 @@ pub const Object = struct {
try o.genCmpLtErrorsLenFunction();
try o.genModuleLevelAssembly();
if (o.compiler_used.items.len > 0) {
const array_llvm_ty = try o.builder.arrayType(o.compiler_used.items.len, .ptr);
const init_val = try o.builder.arrayConst(array_llvm_ty, o.compiler_used.items);
if (o.used.items.len > 0) {
const array_llvm_ty = try o.builder.arrayType(o.used.items.len, .ptr);
const init_val = try o.builder.arrayConst(array_llvm_ty, o.used.items);
const compiler_used_variable = try o.builder.addVariable(
try o.builder.strtabString("llvm.compiler.used"),
try o.builder.strtabString("llvm.used"),
array_llvm_ty,
.default,
);
@ -1317,7 +1317,8 @@ pub const Object = struct {
// Zig emits its own PC table instrumentation.
.PCTable = false,
.NoPrune = false,
.StackDepth = false,
// Workaround for https://github.com/llvm/llvm-project/pull/106464
.StackDepth = true,
.TraceLoads = false,
.TraceStores = false,
.CollectControlFlow = false,
@ -1686,7 +1687,10 @@ pub const Object = struct {
// The void type used here is a placeholder to be replaced with an
// array of the appropriate size after the POI count is known.
const counters_variable = try o.builder.addVariable(.empty, .void, .default);
// Due to error "members of llvm.compiler.used must be named", this global needs a name.
const anon_name = try o.builder.strtabStringFmt("__sancov_gen_.{d}", .{o.used.items.len});
const counters_variable = try o.builder.addVariable(anon_name, .void, .default);
try o.used.append(gpa, counters_variable.toConst(&o.builder));
counters_variable.setLinkage(.private, &o.builder);
counters_variable.setAlignment(comptime Builder.Alignment.fromByteUnits(1), &o.builder);
counters_variable.setSection(try o.builder.string("__sancov_cntrs"), &o.builder);
@ -1741,17 +1745,15 @@ pub const Object = struct {
const array_llvm_ty = try o.builder.arrayType(f.pcs.items.len, .ptr);
const init_val = try o.builder.arrayConst(array_llvm_ty, f.pcs.items);
const pcs_variable = try o.builder.addVariable(.empty, array_llvm_ty, .default);
// Due to error "members of llvm.compiler.used must be named", this global needs a name.
const anon_name = try o.builder.strtabStringFmt("__sancov_gen_.{d}", .{o.used.items.len});
const pcs_variable = try o.builder.addVariable(anon_name, array_llvm_ty, .default);
try o.used.append(gpa, pcs_variable.toConst(&o.builder));
pcs_variable.setLinkage(.private, &o.builder);
pcs_variable.setMutability(.constant, &o.builder);
pcs_variable.setAlignment(Type.usize.abiAlignment(zcu).toLlvm(), &o.builder);
pcs_variable.setSection(try o.builder.string("__sancov_pcs1"), &o.builder);
try pcs_variable.setInitializer(init_val, &o.builder);
try o.compiler_used.appendSlice(gpa, &.{
f.counters_variable.toConst(&o.builder),
pcs_variable.toConst(&o.builder),
});
}
try fg.wip.finish();