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Report From: Delphi-BCB/Debugger/CPU [ Add a report in this area ]

Report #: 80157

Status: Open

Order of registers switched in disassembly of POPCNT instruction

Project: Delphi

Build #: 14.0.3593.25826

Version: 14.0

Submitted By: Philipp S

Report Type: Basic functionality failure

Date Reported: 12/8/2009 10:22:28 AM

Severity: Infrequently encountered problem

Last Updated: 3/20/2012 2:24:39 AM

Platform: All platforms

Internal Tracking #: 273962

Resolution: None (Resolution Comments)

Resolved in Build: : None

Duplicate of: None

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Description

The order of register operands of POPCNT instructions is displayed wrongly in CPU view/disassembly.

For example,

popcnt eax, ecx
is shown as "popcnt ecx, eax" in disassembly

Reference:
Intel? 64 and IA-32 Architectures
Software Developer? Manual
Volume 2B:
Instruction Set Reference, N-Z

Steps to Reproduce:

Place the following code in a project, put a breakpoint on "ret" and compare disassembly with the actual instructions.

procedure POPCNT_DebuggerBugs;
asm
      ret //popcnt is not present on all CPUs so better not execute the following code
      POPCNT eax, ecx
      //Disassembly: F30FB8C1 popcnt ecx, eax
      //Disassembly of corresponding instruction in Visual Studio 2008:  F3 0F B8 C1      popcnt      eax,ecx
      popcnt edx, ecx
      //Disassembly: F30FB8D1 popcnt ecx, edx
      popcnt edx, eax
      //Disassembly: F30FB8D0 popcnt eax, edx
      popcnt ecx, eax
      //Disassembly: F30FB8C8 popcnt eax,ecx
end;

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