mirror of
https://github.com/c64scene-ar/llvm-6502.git
synced 2024-08-05 13:30:38 +00:00
81b28ceab6
- Recognize expressions like "x > -1 ? x : 0" as min/max and turn them into expressions like "x < 0 ? 0 : x", which is easily recognizable as a min/max operation. - Refrain from folding expression like "y/2 < 1" to "y < 2" when the comparison is being used as part of a min or max idiom, like "y/2 < 1 ? 1 : y/2". In that case, the division has another use, so folding doesn't eliminate it, and obfuscates the min/max, making it harder to recognize as a min/max operation. These benefit ScalarEvolution, CodeGen, and anything else that wants to recognize integer min and max. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@56246 91177308-0d34-0410-b5e6-96231b3b80d8
23 lines
654 B
LLVM
23 lines
654 B
LLVM
; RUN: llvm-as < %s | opt -instcombine | llvm-dis | grep { i32 \[%\]sd, \[\[:alnum:\]\]* \\?1\\>} | count 4
|
|
|
|
; Instcombine normally would fold the sdiv into the comparison,
|
|
; making "icmp slt i32 %h, 2", but in this case the sdiv has
|
|
; another use, so it wouldn't a big win, and it would also
|
|
; obfuscate an otherise obvious smax pattern to the point where
|
|
; other analyses wouldn't recognize it.
|
|
|
|
define i32 @foo(i32 %h) {
|
|
%sd = sdiv i32 %h, 2
|
|
%t = icmp slt i32 %sd, 1
|
|
%r = select i1 %t, i32 %sd, i32 1
|
|
ret i32 %r
|
|
}
|
|
|
|
define i32 @bar(i32 %h) {
|
|
%sd = sdiv i32 %h, 2
|
|
%t = icmp sgt i32 %sd, 1
|
|
%r = select i1 %t, i32 %sd, i32 1
|
|
ret i32 %r
|
|
}
|
|
|