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Rollup merge of #70720 - ecstatic-morse:issue-70637, r=oli-obk

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Place TLS initializers with relocations in .tdata

Should fix #70673, although I'm not sure how to test this. Perhaps @joshlf could find a MCVE?

Also adds more context to the FIXME.

r? @oli-obk
This commit is contained in:
Mazdak Farrokhzad 2020-04-03 22:55:12 +02:00 • committed by GitHub
commit 80690b0418
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2 changed files with 25 additions and 16 deletions
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29
src/librustc_codegen_llvm/consts.rs
View file

@ -436,24 +436,21 @@ impl StaticMethods for CodegenCx<'ll, 'tcx> {
//
// We could remove this hack whenever we decide to drop macOS 10.10 support.
if self.tcx.sess.target.target.options.is_like_osx {
assert_eq!(alloc.relocations().len(), 0);
let is_zeroed = {
// Treats undefined bytes as if they were defined with the byte value that
// happens to be currently assigned in mir. This is valid since reading
// undef bytes may yield arbitrary values.
//
// FIXME: ignore undef bytes even with representation `!= 0`.
//
// The `inspect` method is okay here because we checked relocations, and
// because we are doing this access to inspect the final interpreter state
// (not as part of the interpreter execution).
alloc
// The `inspect` method is okay here because we checked relocations, and
// because we are doing this access to inspect the final interpreter state
// (not as part of the interpreter execution).
//
// FIXME: This check requires that the (arbitrary) value of undefined bytes
// happens to be zero. Instead, we should only check the value of defined bytes
// and set all undefined bytes to zero if this allocation is headed for the
// BSS.
let all_bytes_are_zero = alloc.relocations().is_empty()
&& alloc
.inspect_with_undef_and_ptr_outside_interpreter(0..alloc.len())
.iter()
.all(|b| *b == 0)
};
let sect_name = if is_zeroed {
.all(|&byte| byte == 0);
let sect_name = if all_bytes_are_zero {
CStr::from_bytes_with_nul_unchecked(b"__DATA,__thread_bss\0")
} else {
CStr::from_bytes_with_nul_unchecked(b"__DATA,__thread_data\0")

12
src/test/ui/issues/issue-70673.rs Normal file
View file

@ -0,0 +1,12 @@
// Regression test for https://github.com/rust-lang/rust/issues/70673.
// run-pass
#![feature(thread_local)]
#[thread_local]
static A: &u8 = &42;
fn main() {
dbg!(*A);
}