[llvm-bugs] [Bug 32767] llc takes forever on a test with lots of spills

via llvm-bugs llvm-bugs at lists.llvm.org
Mon Apr 24 14:29:50 PDT 2017


http://bugs.llvm.org/show_bug.cgi?id=32767

Davide Italiano <davide at freebsd.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |FIXED
             Status|REOPENED                    |RESOLVED

--- Comment #12 from Davide Italiano <davide at freebsd.org> ---
The commit that fixed the compile time regression is

```
commit 30a921f62a8444a478e456d99022ea847f48336c
Author: Nirav Dave <niravd at google.com>
Date:   Tue Mar 14 00:34:14 2017 +0000

    In visitSTORE, always use FindBetterChain, rather than only when UseAA is
enabled.

        Recommiting with compiler time improvements

        Recommitting after fixup of 32-bit aliasing sign offset bug in
DAGCombiner.

        * Simplify Consecutive Merge Store Candidate Search

        Now that address aliasing is much less conservative, push through
        simplified store merging search and chain alias analysis which only
        checks for parallel stores through the chain subgraph. This is cleaner
        as the separation of non-interfering loads/stores from the
        store-merging logic.

        When merging stores search up the chain through a single load, and
        finds all possible stores by looking down from through a load and a
        TokenFactor to all stores visited.

        This improves the quality of the output SelectionDAG and the output
        Codegen (save perhaps for some ARM cases where we correctly constructs
        wider loads, but then promotes them to float operations which appear
        but requires more expensive constant generation).

        Some minor peephole optimizations to deal with improved SubDAG shapes
(listed below)
[...]

```

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