diff options
Diffstat (limited to 'lib/Target/README.txt')
| -rw-r--r-- | lib/Target/README.txt | 19 |
1 files changed, 19 insertions, 0 deletions
diff --git a/lib/Target/README.txt b/lib/Target/README.txt index 8077680..650eabf 100644 --- a/lib/Target/README.txt +++ b/lib/Target/README.txt @@ -251,3 +251,22 @@ void %test(uint* %P) { ret void } +//===---------------------------------------------------------------------===// + +dag/inst combine "clz(x)>>5 -> x==0" for 32-bit x. + +Compile: + +int bar(int x) +{ + int t = __builtin_clz(x); + return -(t>>5); +} + +to: + +_bar: addic r3,r3,-1 + subfe r3,r3,r3 + blr + + |