X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FCodeGen%2FREADME.txt;h=7f75f65167a382b515f79f547f2988ba06a66564;hb=7d2f2496c1d263eecdc104fd72e847a31d8695b9;hp=8e9ead7f66ec9bccc5c54212d9c1dbae8f99166b;hpb=363bbc011045a9f5710569cc191c520ec25b2907;p=oota-llvm.git

diff --git a/lib/CodeGen/README.txt b/lib/CodeGen/README.txt
index 8e9ead7f66e..7f75f65167a 100644
--- a/lib/CodeGen/README.txt
+++ b/lib/CodeGen/README.txt
@@ -26,45 +26,7 @@ and then "merge" mul and mov:
         sxth r3, r3
         mla r4, r3, lr, r4
 
-It also increase the likelyhood the store may become dead.
-
-//===---------------------------------------------------------------------===//
-
-I think we should have a "hasSideEffects" flag (which is automatically set for
-stuff that "isLoad" "isCall" etc), and the remat pass should eventually be able
-to remat any instruction that has no side effects, if it can handle it and if
-profitable.
-
-For now, I'd suggest having the remat stuff work like this:
-
-1. I need to spill/reload this thing.
-2. Check to see if it has side effects.
-3. Check to see if it is simple enough: e.g. it only has one register
-destination and no register input.
-4. If so, clone the instruction, do the xform, etc.
-
-Advantages of this are:
-
-1. the .td file describes the behavior of the instructions, not the way the
-   algorithm should work.
-2. as remat gets smarter in the future, we shouldn't have to be changing the .td
-   files.
-3. it is easier to explain what the flag means in the .td file, because you
-   don't have to pull in the explanation of how the current remat algo works.
-
-Some potential added complexities:
-
-1. Some instructions have to be glued to it's predecessor or successor. All of
-   the PC relative instructions and condition code setting instruction. We could
-   mark them as hasSideEffects, but that's not quite right. PC relative loads
-   from constantpools can be remat'ed, for example. But it requires more than
-   just cloning the instruction. Some instructions can be remat'ed but it
-   expands to more than one instruction. But allocator will have to make a
-   decision.
-
-4. As stated in 3, not as simple as cloning in some cases. The target will have
-   to decide how to remat it. For example, an ARM 2-piece constant generation
-   instruction is remat'ed as a load from constantpool.
+It also increase the likelihood the store may become dead.
 
 //===---------------------------------------------------------------------===//
 
@@ -200,7 +162,7 @@ synthesize the various copy insertion/inspection methods in TargetInstrInfo.
 
 //===---------------------------------------------------------------------===//
 
-Stack coloring improvments:
+Stack coloring improvements:
 
 1. Do proper LiveStackAnalysis on all stack objects including those which are
    not spill slots.