[M3devel] code quality..

Mon Jan 21 17:04:45 CET 2008

backend.
I think it is correct, if inefficient.

 - Jay

> CC: m3devel at elegosoft.com> From: hosking at cs.purdue.edu> Subject: Re: [M3devel] code quality..> Date: Mon, 21 Jan 2008 11:01:52 -0500> To: jayk123 at hotmail.com> > Is this having the front-end handle return of structs or the backend?> > On Jan 21, 2008, at 9:50 AM, Jay wrote:> > > Unoptimized code quality is really bad,> > even compared to unoptimized C, even compared> > to gcc, and optimized code quality isn't great.> >> > I have this made up C code. I was verifying> > the struct return calling convention.> >> > typedef struct {> > unsigned a;> > unsigned b;> > unsigned c;> > } d;> >> > d F2(unsigned a, unsigned b, unsigned c)> > {> > d e;> > e.a = a * b * c;> > e.b = 123;> > e.c = a - b - c;> > return e;> > }> >> > and then the equivalent Modula-3:> >> > INTERFACE T;> >> > TYPE T1 = RECORD> > a,b,c : INTEGER> > END;> >> > PROCEDURE F2(a,b,c : INTEGER) : T1;> >> > END T.> >> > MODULE T;> >> > PROCEDURE F2(a,b,c : INTEGER) : T1 => > VAR> > e : T1;> > BEGIN> > e.a := (a * b * c);> > e.b := 123;> > e.c := (a - b - c);> > RETURN e;> > END F2;> >> > BEGIN> > END T.> >> > Unoptimized Visual C++ 8.0:> >> > _F2:> > 00000000: 55 push ebp> > 00000001: 8B EC mov ebp,esp> > 00000003: 83 EC 0C sub esp,0Ch> > 00000006: 8B 45 0C mov eax,dword ptr [ebp+0Ch]> > 00000009: 0F AF 45 10 imul eax,dword ptr [ebp+10h]> > 0000000D: 0F AF 45 14 imul eax,dword ptr [ebp+14h]> > 00000011: 89 45 F4 mov dword ptr [ebp-0Ch],eax> > 00000014: C7 45 F8 7B 00 00 mov dword ptr [ebp-8],7Bh> > 00> > 0000001B: 8B 4D 0C mov ecx,dword ptr [ebp+0Ch]> > 0000001E: 2B 4D 10 sub ecx,dword ptr [ebp+10h]> > 00000021: 2B 4D 14 sub ecx,dword ptr [ebp+14h]> > 00000024: 89 4D FC mov dword ptr [ebp-4],ecx> > 00000027: 8B 55 08 mov edx,dword ptr [ebp+8]> > 0000002A: 8B 45 F4 mov eax,dword ptr [ebp-0Ch]> > 0000002D: 89 02 mov dword ptr [edx],eax> > 0000002F: 8B 4D F8 mov ecx,dword ptr [ebp-8]> > 00000032: 89 4A 04 mov dword ptr [edx+4],ecx> > 00000035: 8B 45 FC mov eax,dword ptr [ebp-4]> > 00000038: 89 42 08 mov dword ptr [edx+8],eax> > 0000003B: 8B 45 08 mov eax,dword ptr [ebp+8]> > 0000003E: 8B E5 mov esp,ebp> > 00000040: 5D pop ebp> > 00000041: C3 ret> >> > Visual C++ 8.0 with /O1> >> > It writes the results right into the output.> > _F2:> > 00000000: 55 push ebp> > 00000001: 8B EC mov ebp,esp> > 00000003: 8B 4D 0C mov ecx,dword ptr [ebp+0Ch]> > 00000006: 8B 45 08 mov eax,dword ptr [ebp+8]> > 00000009: 8B D1 mov edx,ecx> > 0000000B: 0F AF 55 10 imul edx,dword ptr [ebp+10h]> > 0000000F: 0F AF 55 14 imul edx,dword ptr [ebp+14h]> > 00000013: 2B 4D 10 sub ecx,dword ptr [ebp+10h]> > 00000016: 89 10 mov dword ptr [eax],edx> > 00000018: 2B 4D 14 sub ecx,dword ptr [ebp+14h]> > 0000001B: C7 40 04 7B 00 00 mov dword ptr [eax+4],7Bh> > 00> > 00000022: 89 48 08 mov dword ptr [eax+8],ecx> > 00000025: 5D pop ebp> > 00000026: C3 ret> >> > with /O2> >> > _F2:> > 00000000: 8B 4C 24 08 mov ecx,dword ptr [esp+8]> > 00000004: 8B 54 24 0C mov edx,dword ptr [esp+0Ch]> > 00000008: 8B 44 24 04 mov eax,dword ptr [esp+4]> > 0000000C: 56 push esi> > 0000000D: 8B 74 24 14 mov esi,dword ptr [esp+14h]> > 00000011: 57 push edi> > 00000012: 8B F9 mov edi,ecx> > 00000014: 0F AF FA imul edi,edx> > 00000017: 0F AF FE imul edi,esi> > 0000001A: 2B CA sub ecx,edx> > 0000001C: 89 38 mov dword ptr [eax],edi> > 0000001E: 2B CE sub ecx,esi> > 00000020: 5F pop edi> > 00000021: C7 40 04 7B 00 00 mov dword ptr [eax+4],7Bh> > 00> > 00000028: 89 48 08 mov dword ptr [eax+8],ecx> > 0000002B: 5E pop esi> > 0000002C: C3 ret> >> > gcc 3.4.5 unoptimized> >> > _F2:> > 00000000: 55 push ebp> > 00000001: 89 E5 mov ebp,esp> > 00000003: 83 EC 18 sub esp,18h> > 00000006: 8B 4D 08 mov ecx,dword ptr [ebp+8]> > 00000009: 8B 45 0C mov eax,dword ptr [ebp+0Ch]> > 0000000C: 0F AF 45 10 imul eax,dword ptr [ebp+10h]> > 00000010: 0F AF 45 14 imul eax,dword ptr [ebp+14h]> > 00000014: 89 45 E8 mov dword ptr [ebp-18h],eax> > 00000017: C7 45 EC 7B 00 00 mov dword ptr [ebp-14h],7Bh> > 00> > 0000001E: 8B 55 10 mov edx,dword ptr [ebp+10h]> > 00000021: 8B 45 0C mov eax,dword ptr [ebp+0Ch]> > 00000024: 29 D0 sub eax,edx> > 00000026: 2B 45 14 sub eax,dword ptr [ebp+14h]> > 00000029: 89 45 F0 mov dword ptr [ebp-10h],eax> > 0000002C: 8B 45 E8 mov eax,dword ptr [ebp-18h]> > 0000002F: 89 01 mov dword ptr [ecx],eax> > 00000031: 8B 45 EC mov eax,dword ptr [ebp-14h]> > 00000034: 89 41 04 mov dword ptr [ecx+4],eax> > 00000037: 8B 45 F0 mov eax,dword ptr [ebp-10h]> > 0000003A: 89 41 08 mov dword ptr [ecx+8],eax> > 0000003D: 89 C8 mov eax,ecx> > 0000003F: C9 leave> > 00000040: C2 04 00 ret 4> > 00000043: 90 nop> > 00000044: 90 nop> > ...more nops for padding...> >> > gcc -O1> >> > _F2:> > 00000000: 55 push ebp> > 00000001: 89 E5 mov ebp,esp> > 00000003: 83 EC 18 sub esp,18h> > 00000006: 89 5D F8 mov dword ptr [ebp-8],ebx> > 00000009: 89 75 FC mov dword ptr [ebp-4],esi> > 0000000C: 8B 45 08 mov eax,dword ptr [ebp+8]> > 0000000F: 8B 4D 0C mov ecx,dword ptr [ebp+0Ch]> > 00000012: 8B 5D 10 mov ebx,dword ptr [ebp+10h]> > 00000015: 8B 75 14 mov esi,dword ptr [ebp+14h]> > 00000018: 89 CA mov edx,ecx> > 0000001A: 0F AF D3 imul edx,ebx> > 0000001D: 0F AF D6 imul edx,esi> > 00000020: 29 D9 sub ecx,ebx> > 00000022: 29 F1 sub ecx,esi> > 00000024: 89 10 mov dword ptr [eax],edx> > 00000026: C7 40 04 7B 00 00 mov dword ptr [eax+4],7Bh> > 00> > 0000002D: 89 48 08 mov dword ptr [eax+8],ecx> > 00000030: 8B 5D F8 mov ebx,dword ptr [ebp-8]> > 00000033: 8B 75 FC mov esi,dword ptr [ebp-4]> > 00000036: 89 EC mov esp,ebp> > 00000038: 5D pop ebp> > 00000039: C2 04 00 ret 4> > 0000003C: 90 nop> > 0000003D: 90 nop> > 0000003E: 90 nop> > 0000003F: 90 nop> >> > I didn't investigate all the switches much and simple -O vs. -O1 > > vs. -O2 vs. -o3> > all do the same.> >> > -O1 -fomit-frame-pointer netted:> >> > _F2:> > 00000000: 83 EC 1C sub esp,1Ch> > 00000003: 89 5C 24 14 mov dword ptr [esp+14h],ebx> > 00000007: 89 74 24 18 mov dword ptr [esp+18h],esi> > 0000000B: 8B 44 24 20 mov eax,dword ptr [esp+20h]> > 0000000F: 8B 4C 24 24 mov ecx,dword ptr [esp+24h]> > 00000013: 8B 5C 24 28 mov ebx,dword ptr [esp+28h]> > 00000017: 8B 74 24 2C mov esi,dword ptr [esp+2Ch]> > 0000001B: 89 CA mov edx,ecx> > 0000001D: 0F AF D3 imul edx,ebx> > 00000020: 0F AF D6 imul edx,esi> > 00000023: 29 D9 sub ecx,ebx> > 00000025: 29 F1 sub ecx,esi> > 00000027: 89 10 mov dword ptr [eax],edx> > 00000029: C7 40 04 7B 00 00 mov dword ptr [eax+4],7Bh> > 00> > 00000030: 89 48 08 mov dword ptr [eax+8],ecx> > 00000033: 8B 5C 24 14 mov ebx,dword ptr [esp+14h]> > 00000037: 8B 74 24 18 mov esi,dword ptr [esp+18h]> > 0000003B: 83 C4 1C add esp,1Ch> > 0000003E: C2 04 00 ret 4> > 00000041: 90 nop> > .. more nops ..> >> > Ok, ready, here goes the unoptimized Modula-3.> > Notice the duplicate copying of the return value and the *doubling* > > in code size.> >> > _T__F2:> > 00000000: 55 push ebp> > 00000001: 89 E5 mov ebp,esp> > 00000003: 57 push edi> > 00000004: 56 push esi> > 00000005: 83 EC 30 sub esp,30h> > 00000008: 8B 55 0C mov edx,dword ptr [ebp+0Ch]> > 0000000B: 8B 45 10 mov eax,dword ptr [ebp+10h]> > 0000000E: 0F AF D0 imul edx,eax> > 00000011: 8B 45 14 mov eax,dword ptr [ebp+14h]> > 00000014: 0F AF D0 imul edx,eax> > 00000017: 8B 45 D4 mov eax,dword ptr [ebp-2Ch]> > 0000001A: 83 E0 00 and eax,0> > 0000001D: 09 D0 or eax,edx> > 0000001F: 89 45 D4 mov dword ptr [ebp-2Ch],eax> > 00000022: 8B 45 D8 mov eax,dword ptr [ebp-28h]> > 00000025: 83 E0 00 and eax,0> > 00000028: 83 C8 7B or eax,7Bh> > 0000002B: 89 45 D8 mov dword ptr [ebp-28h],eax> > 0000002E: 8B 55 0C mov edx,dword ptr [ebp+0Ch]> > 00000031: 8B 45 10 mov eax,dword ptr [ebp+10h]> > 00000034: 29 C2 sub edx,eax> > 00000036: 8B 45 14 mov eax,dword ptr [ebp+14h]> > 00000039: 29 C2 sub edx,eax> > 0000003B: 8B 45 DC mov eax,dword ptr [ebp-24h]> > 0000003E: 83 E0 00 and eax,0> > 00000041: 09 D0 or eax,edx> > 00000043: 89 45 DC mov dword ptr [ebp-24h],eax> > 00000046: 8B 45 08 mov eax,dword ptr [ebp+8]> > 00000049: 89 C2 mov edx,eax> > 0000004B: 8D 45 D4 lea eax,[ebp-2Ch]> > 0000004E: 8D 7D EC lea edi,[ebp-14h]> > 00000051: 89 C6 mov esi,eax> > 00000053: FC cld> > 00000054: A5 movs dword ptr es:[edi],dword > > ptr [esi]> > 00000055: A5 movs dword ptr es:[edi],dword > > ptr [esi]> > 00000056: A5 movs dword ptr es:[edi],dword > > ptr [esi]> > 00000057: 89 D7 mov edi,edx> > 00000059: 8D 75 EC lea esi,[ebp-14h]> > 0000005C: FC cld> > 0000005D: A5 movs dword ptr es:[edi],dword > > ptr [esi]> > 0000005E: A5 movs dword ptr es:[edi],dword > > ptr [esi]> > 0000005F: A5 movs dword ptr es:[edi],dword > > ptr [esi]> > 00000060: 83 C4 30 add esp,30h> > 00000063: 5E pop esi> > 00000064: 5F pop edi> > 00000065: C9 leave> > 00000066: C3 ret> >> > optimized Modula-3 is better, saves the extra copy, but still not > > great:> >> > _T__F2:> > 00000000: 55 push ebp> > 00000001: 89 E5 mov ebp,esp> > 00000003: 57 push edi> > 00000004: 56 push esi> > 00000005: 53 push ebx> > 00000006: 83 EC 10 sub esp,10h> > 00000009: 8B 55 0C mov edx,dword ptr [ebp+0Ch]> > 0000000C: 8B 4D 10 mov ecx,dword ptr [ebp+10h]> > 0000000F: 8B 5D 14 mov ebx,dword ptr [ebp+14h]> > 00000012: 89 D0 mov eax,edx> > 00000014: 0F AF C1 imul eax,ecx> > 00000017: 0F AF C3 imul eax,ebx> > 0000001A: 8B 75 E8 mov esi,dword ptr [ebp-18h]> > 0000001D: 89 45 E8 mov dword ptr [ebp-18h],eax> > 00000020: 8B 45 EC mov eax,dword ptr [ebp-14h]> > 00000023: C7 45 EC 7B 00 00 mov dword ptr [ebp-14h],7Bh> > 00> > 0000002A: 29 CA sub edx,ecx> > 0000002C: 29 DA sub edx,ebx> >> > Huh what does this next instruction achieve?> > 0000002E: 8B 45 F0 mov eax,dword ptr [ebp-10h]> > 00000031: 89 55 F0 mov dword ptr [ebp-10h],edx> > 00000034: 8B 7D 08 mov edi,dword ptr [ebp+8]> > 00000037: 8D 75 E8 lea esi,[ebp-18h]> > 0000003A: FC cld> > 0000003B: A5 movs dword ptr es:[edi],dword > > ptr [esi]> > 0000003C: A5 movs dword ptr es:[edi],dword > > ptr [esi]> > 0000003D: A5 movs dword ptr es:[edi],dword > > ptr [esi]> > 0000003E: 83 C4 10 add esp,10h> > 00000041: 5B pop ebx> > 00000042: 5E pop esi> > 00000043: 5F pop edi> > 00000044: C9 leave> > 00000045: C3 ret> >> > and lastly the integrated backend, which runs much faster, and I > > believe has just one mode,> > somewhat optimized (but still lacks int64 support):> >> > _T__F2:> > 00000000: 55 push ebp> > 00000001: 8B EC mov ebp,esp> > 00000003: 81 EC 18 00 00 00 sub esp,18h> > 00000009: 53 push ebx> > 0000000A: 56 push esi> > 0000000B: 57 push edi> > 0000000C: 8B 5D 10 mov ebx,dword ptr [ebp+10h]> > 0000000F: 0F AF 5D 0C imul ebx,dword ptr [ebp+0Ch]> > 00000013: 0F AF 5D 14 imul ebx,dword ptr [ebp+14h]> > 00000017: 89 5D F4 mov dword ptr [ebp-0Ch],ebx> > 0000001A: C7 45 F8 7B 00 00 mov dword ptr [ebp-8],7Bh> > 00> > 00000021: 8B 55 0C mov edx,dword ptr [ebp+0Ch]> > 00000024: 2B 55 10 sub edx,dword ptr [ebp+10h]> > 00000027: 2B 55 14 sub edx,dword ptr [ebp+14h]> > 0000002A: 89 55 FC mov dword ptr [ebp-4],edx> > 0000002D: 8D 75 F4 lea esi,[ebp-0Ch]> > 00000030: 8B 7D 08 mov edi,dword ptr [ebp+8]> > 00000033: 8B 4E 00 mov ecx,dword ptr [esi]> > 00000036: 89 4F 00 mov dword ptr [edi],ecx> > 00000039: 8B 4E 04 mov ecx,dword ptr [esi+4]> > 0000003C: 89 4F 04 mov dword ptr [edi+4],ecx> > 0000003F: 8B 4E 08 mov ecx,dword ptr [esi+8]> > 00000042: 89 4F 08 mov dword ptr [edi+8],ecx> > 00000045: 8B C7 mov eax,edi> > 00000047: 5F pop edi> > 00000048: 5E pop esi> > 00000049: 5B pop ebx> > 0000004A: C9 leave> > 0000004B: C3 ret> >> > I haven't looked at all this in depth, but the doubling in size, > > the extra copy,> > that the integrated backend's code is fairly small...> >> > - Jay> >> > Shed those extra pounds with MSN and The Biggest Loser! Learn more.> 
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