[PATCH] D18330: [ELF/AArch64] Implemented set of R_AARCH64_TLSDESC_* relocations.

[Ed Maste via llvm-commits]

emaste added inline comments.

================
Comment at: ELF/OutputSections.cpp:322
@@ +321,3 @@
+  // Tail here is amount of such special relocations.
+  Relocs.insert(Relocs.end() - Tail, Reloc);
+}
----------------
I tried a simple experiment with std::vector<int> to get a sense of the scale of the difference. One case started with 10 elements and then added 13 million more with `v.insert(v.end() - 10 , i)` while the other case maintained two vectors and concatenated them at the end. I took the 13 million number from the relocation count in @ruiu's note on linking debug Chrome.

The insert approach takes about 200 times as long in this test. Times in ms:
```
x concat.txt
+ insert.txt
+------------------------------------------------------------------------------+
|x                                                                      ++++  +|
|A                                                                      |_MA_| |
+------------------------------------------------------------------------------+
    N           Min           Max        Median           Avg        Stddev
x   5             2             5             4             4     1.2247449
+   5           770           840           800           802     25.884358
Difference at 95.0% confidence
        798 +/- 26.7237
        19950% +/- 668.094%
        (Student's t, pooled s = 18.3235)
```

Something like @zatrazz's suggestion above sounds reasonable to me, although I'd be happy enough to have a functional version committed first and the change made in a subsequent commit.


http://reviews.llvm.org/D18330