Bug 5364 – optimizer kills high dword of -1

dmd 2.050. the code: import std.stdio; long b(long bmax){ if(true){ } if(bmax >= 0) bmax = -1; return bmax; } void main(){ writeln(b(0)); } the compilation: dmd -O -inline test.d the result: 4294967295

Works on Windows. (Tried 2.020, 2.030, 2.040, 2.049, 2.050, 2.051, also tried -release).

I can't reproduce this on Linux64 either, with the DMD from git master. Unless somebody can reproduce this, it should be closed as WORKSFORME.

I am still seeing this behavior on DMD32 2.054, Fedora 14 64 bit. I don't have internet access at home, so I can't test against DMD from git master.

just built dmd from github, and I am seeing this behavior there, too.

FWIW, just tested dmd 2.055 against this issue - 32 bit version has it, 64 bit version doesn't.

Could you please post the disassembly of main() and b() when compiled with -O -inline?

the compile: ~/Downloads/dmd2/linux/bin32/dmd pest -inline -O the assembly dump: 08085344 <_D4pest1bFlZl>: 8085344: 55 push ebp 8085345: 8b ec mov ebp,esp 8085347: 8b 4d 0c mov ecx,DWORD PTR [ebp+0xc] 808534a: 8b 44 24 08 mov eax,DWORD PTR [esp+0x8] 808534e: 85 c9 test ecx,ecx 8085350: 7c 0d jl 808535f <_D4pest1bFlZl+0x1b> 8085352: 7f 04 jg 8085358 <_D4pest1bFlZl+0x14> 8085354: 85 c0 test eax,eax 8085356: 72 07 jb 808535f <_D4pest1bFlZl+0x1b> 8085358: b8 ff ff ff ff mov eax,0xffffffff 808535d: 31 c9 xor ecx,ecx 808535f: 5d pop ebp 8085360: 8b d1 mov edx,ecx 8085362: c2 08 00 ret 0x8 8085365: 90 nop 8085366: 90 nop 8085367: 90 nop 08085368 <_Dmain>: 8085368: 55 push ebp 8085369: 8b ec mov ebp,esp 808536b: 6a 00 push 0x0 808536d: 6a 00 push 0x0 808536f: e8 d0 ff ff ff call 8085344 <_D4pest1bFlZl> 8085374: 52 push edx 8085375: 50 push eax 8085376: b8 84 67 0c 08 mov eax,0x80c6784 808537b: 6a 0a push 0xa 808537d: e8 22 00 00 00 call 80853a4 <_D3std5stdio4File14__T5writeTlTaZ5writeMFlaZv> 8085382: 31 c0 xor eax,eax 8085384: 5d pop ebp 8085385: c3 ret 8085386: 90 nop 8085387: 90 nop

Here's what it does on 32-bit Windows. The commented line is where the difference is. mov ECX,8[ESP] mov EAX,4[ESP] test ECX,ECX jl Lsecond jg Lfirst test EAX,EAX jb Lsecond Lfirst: mov EAX,0xFFFFFFFF mov ECX,EAX // xor ECX, ECX on failing case Lsecond: mov EDX,ECX ret 8

I can reproduce the problem on Linux.

https://github.com/D-Programming-Language/dmd/commit/b1a31e2e9f35e523777467ae74eebfc99a3bb193 https://github.com/D-Programming-Language/dmd/commit/bc95288b4fb56166edc8c066eca1e17d97446f2e

*** Issue 6537 has been marked as a duplicate of this issue. ***