| ; RUN: llc < %s -march=x86-64 | FileCheck %s |
| ; CHECK: addl |
| |
| ; The two additions are the same , but have different flags. |
| ; In theory this code should never be generated by the frontend, but this |
| ; tries to test that two identical instructions with two different flags |
| ; actually generate two different nodes. |
| ; |
| ; Normally the combiner would see this condition without the flags |
| ; and optimize the result of the sub into a register clear |
| ; (the final result would be 0). With the different flags though the combiner |
| ; needs to keep the add + sub nodes, because the two nodes result as different |
| ; nodes and so cannot assume that the subtraction of the two nodes |
| ; generates 0 as result |
| define i32 @foo(i32 %a, i32 %b) { |
| %1 = add i32 %a, %b |
| %2 = add nsw i32 %a, %b |
| %3 = sub i32 %1, %2 |
| ret i32 %3 |
| } |
