On Tuesday, 23 May 2017 at 15:37:39 UTC, Stefan Koch wrote:
The compiler does indeed seem to optimize the code somewhat. Although the generated asm still looks wired. http://asm.dlang.org/#compilers:!((compiler:dmd_nightly,options:'-dip25+-O+-release+-inline+-m32',source:'import+core.checkedint%3B%0A%0Aalias+T+%3D+ulong%3B%0Aextern+(C)+T+foo(uint+x,+uint+y,+ref+bool+overflow)%0A%7B%0A+++return+mulu(x,+y,+overflow)%3B%0A%7D%0A')),filterAsm:(binary:!t,intel:!t),version:3
The jbe (jump-below-equal) does check the overflow flag (and redundantly the zero-flag) here and sets the bool which represents overflow to one.
