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seg fault on floating point code #21142

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WalterBright opened this issue Apr 3, 2025 · 0 comments · May be fixed by #21148
Open

seg fault on floating point code #21142

WalterBright opened this issue Apr 3, 2025 · 0 comments · May be fixed by #21148
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Arch:x86_64 Issues specific to x86_64 Compiler:Backend glue code, optimizer, code generation Severity:Crash built program crashes

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@WalterBright
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The code:

void main() {
       double a,b,c;
       double* pa,pb;

       a = 5;
       b = a++;
       assert(a == 6);
       pa = &a;
       pb = &b;
       *pb = (*pa)++;
}

The generated code:

_Dmain:
0000:   55                       push      RBP
0001:   48 8B EC                 mov       RBP,RSP
0004:   48 83 EC 10              sub       RSP,010h
0008:   F2 0F 10 05 FC FF FF FF  movsd     XMM0,[0FFFFFFFCh][RIP]
0010:   F2 48 0F 11 45 F0        movsd     -010h[RBP],XMM0
0016:   F2 48 0F 11 45 F8        movsd     -8[RBP],XMM0
001c:   31 C0                    xor       EAX,EAX
001e:   F2 0F 10 0D FC FF FF FF  movsd     XMM1,[0FFFFFFFCh][RIP]
0026:   F2 48 0F 11 4D F0        movsd     -010h[RBP],XMM1
002c:   F2 48 0F 10 55 F0        movsd     XMM2,-010h[RBP]
0032:   F2 0F 10 DA              movsd     XMM3,XMM2
0036:   48 B8 00 00 00 00 00 00 F0 3F  mov       RAX,03FF0000000000000h
0040:   66 48 0F 6E C0           movd      XMM0,RAX
0045:   F2 0F 58 D0              addsd     XMM2,XMM0
0049:   F2 48 0F 11 55 F0        movsd     -010h[RBP],XMM2
004f:   F2 48 0F 11 5D F8        movsd     -8[RBP],XMM3
0055:   F2 0F 10 4D F0           movsd     XMM1,-010h[RBP]
005a:   F2 0F 10 15 FC FF FF FF  movsd     XMM2,[0FFFFFFFCh][RIP]
0062:   66 0F 2E D1              ucomisd   XMM2,XMM1
0066:   7A 02                    jp        L6a
0068:   74 0F                    je        L79
006a:   BE 08 00 00 00           mov       ESI,8
006f:   BF 00 00 00 00           mov       EDI,0
0074:   E8 00 00 00 00           call      L0
0079:   48 8D 45 F0              lea       RAX,-010h[RBP]  <= pointer value put in RAX
007d:   48 8D 4D F8              lea       RCX,-8[RBP]
0081:   F2 48 0F 10 00           movsd     XMM0,[RAX]
0086:   F2 0F 10 C8              movsd     XMM1,XMM0
008a:   48 B8 00 00 00 00 00 00 F0 3F  mov       RAX,03FF0000000000000h  <= stepped on RAX pointer value
0094:   66 48 0F 6E D0           movd      XMM2,RAX
0099:   F2 0F 58 C2              addsd     XMM0,XMM2
009d:   F2 48 0F 11 00           movsd     [RAX],XMM0   <= seg fault here
00a2:   F2 48 0F 11 09           movsd     [RCX],XMM1
00a7:   C9                       leave
00a8:   C3                       ret
@WalterBright WalterBright added Arch:x86_64 Issues specific to x86_64 Compiler:Backend glue code, optimizer, code generation Severity:Crash built program crashes labels Apr 3, 2025
WalterBright added a commit to WalterBright/dmd that referenced this issue Apr 4, 2025
@WalterBright
fix dlang#21142 seg fault on floating point code
0d11b2a
@WalterBright WalterBright linked a pull request Apr 4, 2025 that will close this issue
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@dkorpel dkorpel linked a pull request Apr 4, 2025 that will close this issue
fix #21142 seg fault on floating point code #21148
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Arch:x86_64 Issues specific to x86_64 Compiler:Backend glue code, optimizer, code generation Severity:Crash built program crashes
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fix #21142 seg fault on floating point code WalterBright/dmd
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