What do c2 Phases do?

On the Forums, someone asked the good question of "What do the C2 phases actually do?"  Andy got some info from our documentation team about the phases, so I thought I'd also add them here.  Expect this info in future version of the SDK:

 

Phase	Phase Action
CxxIL Reader	Converts CxxIL to Phoenix IR.
Warnings Analysis Detection Phase	Detects and emits back-end warnings (C4700, C4701, and so on).
Add CallGraph Call Site Information	Modifies call graph (if present) to refer to specific call sites within the function.
Inliner	Inlines functions.
Type Checker	Verifies that IR is correctly typed.
Flow Optimization	Streamlines control flow (for example, eliminates jumps to jumps).
MIR Lower	Lowers object model instructions.
Loop recognition and loop transformations	Performs basic loop restructuring.
Global optimization	Performs optimizations such as constant propagation, global value numbering, constant subexpression elimination, and dead code elimination.
Loop optimizations	Recognizes induction variables for strength reduction and loop-invariant code motion.
GS Shadow Copying	Implements the /GS option (stack security).
GS Security Cookie Allocation	Implements the /GS option (stack security).
X86 scalar Sse	Prepares the compiler to use SSE floating point instead of x87 floating point.
Canonicalize	Transforms IR to canonical form in preparation for lowering.
ShiftExpansion Strength Reduction	Transform multiplications and divisions by constants into shifts and additions.
Address Mode Builder	Transforms HIR/MIR to take advantage of target architecture's built-in addressing modes.
Lower	Lowers most instructions to machine level.
SSA-based idioms optimization phase	Performs classic "peephole" optimizations.
Priority Order Register Allocation	Assigns registers to operands.
X87 Stack Allocation	Allocates the x87 stack.
GS Security Cookie Initialization and Check	Implements the /GS option (stack security).
Native EH Lower	Expresses exception handling the way that the run-time convention expects.
Stack Packer	Assigns stack locations to operands.
Frame Generation	Determines shape of stack frame for the function.
Switch Lower	Lowers switch instructions.
Dead Stores	Removes dead stores (that is, stores that are guaranteed not to be read).
Block Layout	Places IR in final order.
Flow Optimization	Removes jump-to-jump and jump-to-next instructions.
Finish EH Lower	Finishes the process begun by Native EH Lower.
Encoding	Produces machine encoding for IR, and debug information.
Emission	Puts encoded IR into the object file.
Emit Referenced Symbols	Verifies the references made from the encoded IR to ensure that the compiler emits a fully closed set of functions and data.
Assembly Listing	Produces the .asm listing file.