6502/llvm-6502
1
0
Fork 0
mirror of https://github.com/c64scene-ar/llvm-6502.git synced 2024-12-14 11:32:34 +00:00
Code Issues Projects Releases Wiki Activity

Add optimization to Target/README.txt.

Browse Source 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@110543 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Nick Lewycky 2010-08-08 07:04:25 +00:00
parent 1bb580a3aa
commit b1e4eebec0
1 changed files with 17 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

18
lib/Target/README.txt
View File

@ -1919,5 +1919,21 @@ something like the following, which eliminates a branch:
ret
.LBB0_2:
jmp foo # TAILCALL
//===---------------------------------------------------------------------===//
Given a branch where the two target blocks are identical ("ret i32 %b" in
both), simplifycfg will simplify them away. But not so for a switch statement:
define i32 @f(i32 %a, i32 %b) nounwind readnone {
entry:
switch i32 %a, label %bb3 [
i32 4, label %bb
i32 6, label %bb
]
bb: ; preds = %entry, %entry
ret i32 %b
bb3: ; preds = %entry
ret i32 %b
}
//===---------------------------------------------------------------------===//