Question about -ftree-* optimizations in -O1

[Jiaqi Tan]

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?

-ftree-bit-ccp
-ftree-builtin-call-dce
-ftree-ccp
-ftree-ch
-ftree-copyrename
-ftree-dce
-ftree-dominator-opts
-ftree-dse
-ftree-forwprop
-ftree-fre
-ftree-phiprop
-ftree-sra
-ftree-pta
-ftree-ter

Thanks!
Jiaqi Tan