Bug 13023 – optimizer produces wrong code for comparision and division of ulong

The following code fails when compiling with -O on a 64-bit system. Note that the problem does not appear when removing the writefln() or not passing n as a parameter. Using long instead of ulong solves the problem as well. import std.stdio; void foo(ulong n) { ulong k = 0; writefln("%s", k>=n/2); // correctly print 'false' if(k>=n/2) // triggers with -O assert(false); } void main() { ulong n = (1UL<<32)*2; foo(n); }

This looks like another REX issue, dmd is comparing 4 bytes instead of 8 against zero. The lower 4 bytes of (1UL<<32)*2/2 are all zero.

Commits pushed to master at https://github.com/D-Programming-Language/dmd https://github.com/D-Programming-Language/dmd/commit/1fced8b109eb74b03adc232ca6057c2235505049 Fix Issue 13023 - optimizer produces wrong code for comparision and division of ulon https://github.com/D-Programming-Language/dmd/commit/f79c6c576bae0a14edc4b4eb67134f753f7a7b8b Merge pull request #3809 from yebblies/issue13023 Issue 13023 - optimizer produces wrong code for comparision and division of ulong

Commit pushed to dmd-1.x at https://github.com/D-Programming-Language/dmd https://github.com/D-Programming-Language/dmd/commit/1c85734dad8e5704105c37603a694bac34925095 Fix Issue 13023 - optimizer produces wrong code for comparision and division of ulon

Commit pushed to 2.066 at https://github.com/D-Programming-Language/dmd https://github.com/D-Programming-Language/dmd/commit/780325cc7b58ed22fdddbeac20cc6a0d957cb28c Merge pull request #3809 from yebblies/issue13023 Issue 13023 - optimizer produces wrong code for comparision and division of ulong

Commit pushed to master at https://github.com/D-Programming-Language/dmd https://github.com/D-Programming-Language/dmd/commit/780325cc7b58ed22fdddbeac20cc6a0d957cb28c Merge pull request #3809 from yebblies/issue13023