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Diffstat (limited to 'lib/Target/README.txt')
| -rw-r--r-- | lib/Target/README.txt | 26 |
1 files changed, 26 insertions, 0 deletions
diff --git a/lib/Target/README.txt b/lib/Target/README.txt index 29bd10949e..bedc893fbb 100644 --- a/lib/Target/README.txt +++ b/lib/Target/README.txt @@ -2047,3 +2047,29 @@ entry: } //===---------------------------------------------------------------------===// +clang -O3 currently compiles this code + +int g(unsigned int a) { + unsigned int c[100]; + c[10] = a; + c[11] = a; + unsigned int b = c[10] + c[11]; + if(b > a*2) a = 4; + else a = 8; + return a + 7; +} + +into + +define i32 @g(i32 a) nounwind readnone { + %add = shl i32 %a, 1 + %mul = shl i32 %a, 1 + %cmp = icmp ugt i32 %add, %mul + %a.addr.0 = select i1 %cmp, i32 11, i32 15 + ret i32 %a.addr.0 +} + +The icmp should fold to false. This CSE opportunity is only available +after GVN and InstCombine have run. + +//===---------------------------------------------------------------------===// |