Clang: enable -instcombine-lower-dbg-declare=1

This enables better optimized debug info for address-taken values
at the cost of potentially inaccurate debug info in some situations.

We believe turning this on is the right trade-off for developers
debugging Chromium on all platforms, but especially on Windows where
values that are available in MSVC's debug info would otherwise show
as unavailable when using Clang.

The goal ( is to make Clang's optimized
debug info good enough in all cases that this compromise is not

Note: This requires Clang r313108 or later.

Bug: 761633, 753736, 765793
Change-Id: Ia0ed38c499fac282a3c8ab27c5fd5571fdfab84d
Commit-Queue: Hans Wennborg <>
Reviewed-by: Nico Weber <>
Cr-Commit-Position: refs/heads/master@{#502428}
1 file changed