llvm-6502

mirror of https://github.com/c64scene-ar/llvm-6502.git synced 2025-01-15 07:34:33 +00:00

History

Chris Lattner 010de25f42 Implement a simple optimization for the termination condition of the loop.

The termination condition actually wants to use the post-incremented value
of the loop, not a new indvar with an unusual base.

On PPC, for example, this allows us to compile
LoopStrengthReduce/exit_compare_live_range.ll to:

_foo:
        li r2, 0
.LBB_foo_1:     ; no_exit
        li r5, 0
        stw r5, 0(r3)
        addi r2, r2, 1
        cmpw cr0, r2, r4
        bne .LBB_foo_1  ; no_exit
        blr

instead of:

_foo:
        li r2, 1                ;; IV starts at 1, not 0
.LBB_foo_1:     ; no_exit
        li r5, 0
        stw r5, 0(r3)
        addi r5, r2, 1
        cmpw cr0, r2, r4
        or r2, r5, r5           ;; Reg-reg copy, extra live range
        bne .LBB_foo_1  ; no_exit
        blr

This implements LoopStrengthReduce/exit_compare_live_range.ll


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@22699 91177308-0d34-0410-b5e6-96231b3b80d8

2005-08-08 05:28:22 +00:00

Analysis

* Unbreak optimized build (noticed by Eric van Riet Paap)

2005-08-04 14:16:48 +00:00