diff options
Diffstat (limited to 'lib/Target/ARM/README.txt')
| -rw-r--r-- | lib/Target/ARM/README.txt | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/lib/Target/ARM/README.txt b/lib/Target/ARM/README.txt index 8ba9a27..2f6842e 100644 --- a/lib/Target/ARM/README.txt +++ b/lib/Target/ARM/README.txt @@ -681,3 +681,21 @@ is compiled and optimized to: str r1, [r0] //===---------------------------------------------------------------------===// + +Improve codegen for select's: +if (x != 0) x = 1 +if (x == 1) x = 1 + +ARM codegen used to look like this: + mov r1, r0 + cmp r1, #1 + mov r0, #0 + moveq r0, #1 + +The naive lowering select between two different values. It should recognize the +test is equality test so it's more a conditional move rather than a select: + cmp r0, #1 + movne r0, #0 + +Currently this is a ARM specific dag combine. We probably should make it into a +target-neutral one. |
