From fffbcc8d2995987823dfcda341f4102818d508d2 Mon Sep 17 00:00:00 2001 From: Dylan MacKenzie Date: Thu, 2 Apr 2020 13:46:51 -0700 Subject: [PATCH 1/2] Place TLS initializers with relocations in .tdata --- src/librustc_codegen_llvm/consts.rs | 29 +++++++++++++---------------- 1 file changed, 13 insertions(+), 16 deletions(-) diff --git a/src/librustc_codegen_llvm/consts.rs b/src/librustc_codegen_llvm/consts.rs index db92f3d382f6e..6fe5ad37f30ab 100644 --- a/src/librustc_codegen_llvm/consts.rs +++ b/src/librustc_codegen_llvm/consts.rs @@ -437,24 +437,21 @@ 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") From f030635e667d3927ccaf4dbbab1c096485d87049 Mon Sep 17 00:00:00 2001 From: Oliver Scherer Date: Fri, 3 Apr 2020 10:50:06 -0700 Subject: [PATCH 2/2] Add regression test for #70673 --- src/test/ui/issues/issue-70673.rs | 12 ++++++++++++ 1 file changed, 12 insertions(+) create mode 100644 src/test/ui/issues/issue-70673.rs diff --git a/src/test/ui/issues/issue-70673.rs b/src/test/ui/issues/issue-70673.rs new file mode 100644 index 0000000000000..3561f40127737 --- /dev/null +++ b/src/test/ui/issues/issue-70673.rs @@ -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); +}