[LLVMbugs] [Bug 12102] New: x86 assembly printer fails to print "mov eax, [0xfed00010]" correctly

[bugzilla-daemon at llvm.org]

http://llvm.org/bugs/show_bug.cgi?id=12102

             Bug #: 12102
           Summary: x86 assembly printer fails to print "mov eax,
                    [0xfed00010]" correctly
           Product: new-bugs
           Version: 3.0
          Platform: PC
        OS/Version: All
            Status: NEW
          Severity: release blocker
          Priority: P
         Component: new bugs
        AssignedTo: unassignedbugs at nondot.org
        ReportedBy: benjamin.j.panning at intel.com
                CC: llvmbugs at cs.uiuc.edu
    Classification: Unclassified


The assembly printer for x86 fails to print certain MOVrm instructions
correctly.  This can be reproduced following these steps:

*** 1. Create a basic C++ example to be compiled:

int main() {
  int* x = (int*)0xfed00010; // HPET MMIO
  return *x; // Read on this MMIO
}

*** 2. Run this through clang using the following command (Windows):

  clang.exe -emit-llvm -S -o source.ll source.cpp

*** 3. Run this through llc using the following command (Windows):

  llc.exe -filetype=asm -x86-asm-syntax=intel -print-after-all source.ll

*** 4. Examine the final assembly product (source.s):

  # MMIO read shows up as this...
  mov     EAX, -19922928 # mov     EAX, 0xfed00010


I've examined the object file produced when I change the -filetype to "obj",
and the binary appears to be correct.  Decoding the binary results in the
following instruction:

  mov     eax, dword ptr [0xfed00010]

Looking at the "IR Dump After X86 AT&T-Style Assembly Printer" yields the
following instruction:

  %EAX<def> = MOV32rm %noreg, 1, %noreg, -19922928, %noreg; mem:LD4[%0]

This looks correct, and it's only when this is printed does the error occur. 
This leads me to believe the bug is isolated within the assembly printer.

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