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Rollup merge of #41015 - arielb1:new-block-stack, r=alexcrichton

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mark build::cfg::start_new_block as inline(never)

LLVM has a bug - [PR32488](https://bugs.llvm.org//show_bug.cgi?id=32488) - where it fails to deduplicate allocas in some
circumstances. The function `start_new_block` has allocas totalling 1216
bytes, and when LLVM inlines several copies of that function into
the recursive function `expr::into`, that function's stack space usage
goes into tens of kiBs, causing stack overflows.

Mark `start_new_block` as inline(never) to keep it from being inlined,
getting stack usage under control.

Fixes #40493.
Fixes #40573.

r? @eddyb
This commit is contained in:
Ariel Ben-Yehuda 2017-04-05 23:01:09 +00:00 committed by GitHub
parent 9d074473da 09ac56d6ef
commit b712950d7b
1 changed files with 3 additions and 0 deletions
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3
src/librustc_mir/build/cfg.rs
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@ -25,6 +25,9 @@ pub fn block_data_mut(&mut self, blk: BasicBlock) -> &mut BasicBlockData<'tcx> {
&mut self.basic_blocks[blk]
}
// llvm.org/PR32488 makes this function use an excess of stack space. Mark
// it as #[inline(never)] to keep rustc's stack use in check.
#[inline(never)]
pub fn start_new_block(&mut self) -> BasicBlock {
self.basic_blocks.push(BasicBlockData::new(None))
}