Bug 8840 – calculating minimum of longs with following comparison compiles to wrong code when enabling the optimizer

import core.stdc.stdio; long foo() { return 4; } void main() { long f1 = foo(); long f2 = foo(); long f = (f1 < f2 ? f1 : f2); int len = (f == 0 ? 0 : printf("%llx\n", f)); } compiled with "dmd -o" and running produces the output "400000004" instead of just "4". Here's the disassembly: _D4test3fooFZl comdat assume CS:_D4test3fooFZl mov EAX,4 xor EDX,EDX ret _D4test3fooFZl ends __Dmain comdat assume CS:__Dmain L0: sub ESP,0Ch push EBX push ESI call near ptr _D4test3fooFZl mov 8[ESP],EAX mov 0Ch[ESP],EDX call near ptr _D4test3fooFZl cmp EDX,0Ch[ESP] jl L33 jg L25 cmp EAX,8[ESP] jbe L33 L25: mov ECX,0Ch[ESP] mov EBX,8[ESP] mov ESI,ECX or ESI,EBX jmp short L39 L33: mov ECX,EDX mov EBX,EAX or ECX,EBX L39: je L4B mov EAX,offset FLAT:_DATA push ECX push EBX push EAX call near ptr _printf add ESP,0Ch L4B: xor EAX,EAX pop ESI pop EBX add ESP,0Ch ret __Dmain ends Note that ECX is pushed in the call to printf, but it is the result of hiword|loword in the part after L33. dmc suffers from the same problem.

Raising severity to blocker. No compiler releases should occur until this is fixed.

Wow. How has this one not shown its ugly face before?

Commit pushed to dmd-1.x at https://github.com/D-Programming-Language/dmd https://github.com/D-Programming-Language/dmd/commit/551e86b022a61064d11fa43924d18222ed366d80 fix Issue 8840 - calculating minimum of longs with following comparison compiles to wrong code when enabling the optimizer

Commit pushed to master at https://github.com/D-Programming-Language/dmd https://github.com/D-Programming-Language/dmd/commit/fdb413235448e27dad0aab615837b051483de150 fix Issue 8840 - calculating minimum of longs with following comparison compiles to wrong code when enabling the optimizer

Commit pushed to master at https://github.com/D-Programming-Language/dmd https://github.com/D-Programming-Language/dmd/commit/881f9fcb740516391e1c7dd1a3e39046dd21e74a test case for issue 8840