llvm-6502/lib/Target/ARM/README-Thumb.txt
Evan Cheng a8e2989ece ARM backend contribution from Apple.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@33353 91177308-0d34-0410-b5e6-96231b3b80d8
2007-01-19 07:51:42 +00:00

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//===---------------------------------------------------------------------===//
// Random ideas for the ARM backend (Thumb specific).
//===---------------------------------------------------------------------===//
* Add support for compiling functions in both ARM and Thumb mode, then taking
the smallest.
* Add support for compiling individual basic blocks in thumb mode, when in a
larger ARM function. This can be used for presumed cold code, like paths
to abort (failure path of asserts), EH handling code, etc.
* Thumb doesn't have normal pre/post increment addressing modes, but you can
load/store 32-bit integers with pre/postinc by using load/store multiple
instrs with a single register.
* Make better use of high registers r8, r10, r11, r12 (ip). Some variants of add
and cmp instructions can use high registers. Also, we can use them as
temporaries to spill values into.