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Fix static relocation model for PowerPC64

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We now also use `should_assume_dso_local()` for declarations and port two
additional cases from clang:
- Exclude PPC64 [1]
- Exclude thread-local variables [2]

[1]: 033138ea45/clang/lib/CodeGen/CodeGenModule.cpp (L1038-L1040)
[2]: 033138ea45/clang/lib/CodeGen/CodeGenModule.cpp (L1048-L1050)
This commit is contained in:
Boris-Chengbiao Zhou 2021-05-25 23:54:07 +02:00
parent e51830b90a
commit 4a76934aa7
6 changed files with 47 additions and 47 deletions
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44
compiler/rustc_codegen_llvm/src/mono_item.rs
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@ -37,7 +37,7 @@ impl PreDefineMethods<'tcx> for CodegenCx<'ll, 'tcx> {
unsafe {
llvm::LLVMRustSetLinkage(g, base::linkage_to_llvm(linkage));
llvm::LLVMRustSetVisibility(g, base::visibility_to_llvm(visibility));
if self.should_assume_dso_local(linkage, visibility) {
if self.should_assume_dso_local(g, false) {
llvm::LLVMRustSetDSOLocal(g, true);
}
}
@ -85,7 +85,7 @@ impl PreDefineMethods<'tcx> for CodegenCx<'ll, 'tcx> {
attributes::from_fn_attrs(self, lldecl, instance);
unsafe {
if self.should_assume_dso_local(linkage, visibility) {
if self.should_assume_dso_local(lldecl, false) {
llvm::LLVMRustSetDSOLocal(lldecl, true);
}
}
@ -95,31 +95,51 @@ impl PreDefineMethods<'tcx> for CodegenCx<'ll, 'tcx> {
}
impl CodegenCx<'ll, 'tcx> {
/// Whether a definition (NB: not declaration!) can be assumed to be local to a group of
/// Whether a definition or declaration can be assumed to be local to a group of
/// libraries that form a single DSO or executable.
pub(crate) unsafe fn should_assume_dso_local(
&self,
linkage: Linkage,
visibility: Visibility,
llval: &llvm::Value,
is_declaration: bool,
) -> bool {
if matches!(linkage, Linkage::Internal | Linkage::Private) {
let linkage = llvm::LLVMRustGetLinkage(llval);
let visibility = llvm::LLVMRustGetVisibility(llval);
if matches!(linkage, llvm::Linkage::InternalLinkage | llvm::Linkage::PrivateLinkage) {
return true;
}
if visibility != Visibility::Default && linkage != Linkage::ExternalWeak {
if visibility != llvm::Visibility::Default && linkage != llvm::Linkage::ExternalWeakLinkage
{
return true;
}
// Symbols from executables can't really be imported any further.
let all_exe = self.tcx.sess.crate_types().iter().all(|ty| *ty == CrateType::Executable);
let is_declaration_for_linker =
is_declaration || linkage == llvm::Linkage::AvailableExternallyLinkage;
if all_exe && !is_declaration_for_linker {
return true;
}
// PowerPC64 prefers TOC indirection to avoid copy relocations.
if matches!(&*self.tcx.sess.target.arch, "powerpc64" | "powerpc64le") {
return false;
}
// Thread-local variables generally don't support copy relocations.
let is_thread_local_var = llvm::LLVMIsAGlobalVariable(llval)
.map(|v| llvm::LLVMIsThreadLocal(v) == llvm::True)
.unwrap_or(false);
if is_thread_local_var {
return false;
}
// Static relocation model should force copy relocations everywhere.
if self.tcx.sess.relocation_model() == RelocModel::Static {
return true;
}
// Symbols from executables can't really be imported any further.
if self.tcx.sess.crate_types().iter().all(|ty| *ty == CrateType::Executable) {
return true;
}
return false;
}
}