On 06/16/2016 07:46 PM, Libin Dang wrote:
On 06/17/2016 06:39 AM, Jiaqi Tan wrote:
Hi,
What does the tree in "-ftree-*" refer to in the following
optimization flags that are turned on as part of -O1 in gcc? Does the
tree refer to an internal GCC data structure?
Yes. For further details please see:
https://gcc.gnu.org/onlinedocs/gccint/Tree-SSA.html
Correct.
Essentially before the introduction of tree-ssa all optimizers of
significance were written to optimize the lower level RTL IL. The
introduction of the tree-ssa optimizers brought optimizations to the
higher tree/gimple IL.
The new optimizers needed switches and we prefixed all of them with
-ftree. It may have been a bad choice since ultimately the users of GCC
don't much care about what IL a particular optimizer works on. But at
this point those options are set in stone.
jeff
