Re: [Jikesrvm-researchers] IA32, OPT Compiler: Assembling MOV without base or index, just with displacement

[Stephen F. <sj...@us...>]

Hi Matthias,
    I believe Julian added this functionality on Nov. 16.    See the CVS
commit history page to see what files to pick up.  Or  - you can pick up
the HEAD of the CVS repository.

SJF

------------------------------------------------------------------------
Stephen Fink
IBM T.J. Watson Research Center
sj...@us...
(914)784-7776



                                                                                                                                              
                      Matthias Hauswirth                                                                                                      
                      <Matthias.Hauswirth@Colorado.EDU>                    To:       jikesrvm-researchers                                     
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                      usf.ibm.com                                          Subject:  [Jikesrvm-researchers] IA32, OPT Compiler: Assembling    
                                                                            MOV without base or index, just with displacement                 
                                                                                                                                              
                      12/14/2001 12:29 AM                                                                                                     
                      Please respond to jikesrvm-researchers                                                                                  
                                                                                                                                              
                                                                                                                                              



Working on my MIR instrumentations I discovered a feature I need. I want
to write to a constant memory address (an address, e.g. 0x61000000, I
choose at boot image writing time). For this I want to insert a MIR
instruction. I do the following:

-----------------------------------------------------------------------
OPT_Instruction i = MIR_Move.create(
    OPT_Operators.IA32_MOV,
    OPT_MemoryOperand.D(
        0x61000000,
        (byte)0x04,  /*move a doubleword(32bits)*/
        null, /*location*/
        null /*guard*/
    ),
    OPT_RVMIRTools.R(eax) // whatever value I want to store
);
-----------------------------------------------------------------------

This leads to an exception when this chunk of MIR code gets assembled:

-----------------------------------------------------------------------
OPT_Compiler failure during compilation of VM_GCUtil.boot ()V
java.lang.NullPointerException
        at OPT_AssemblerBase.getBase(OPT_AssemblerBase.java:158)
        at OPT_Assembler.doMOV(OPT_Assembler.java:3475)
        at OPT_Assembler.doInst(OPT_Assembler.java:8733)
        at OPT_AssemblerBase.generateCode(OPT_AssemblerBase.java:489)
        at
OPT_ConvertMIRtoMC$AssemblerDriver.perform(OPT_ConvertMIRtoMC.java:94)
        at OPT_CompilerPhase.performPhase(OPT_CompilerPhase.java:110)
        at
OPT_OptimizationPlanAtomicElement.perform(OPT_OptimizationPlanAtomicElement.java:68)

        at
OPT_OptimizationPlanCompositeElement.perform(OPT_OptimizationPlanCompositeElement.java:124)

        at OPT_CompilationPlan.execute(OPT_CompilationPlan.java:156)
        at OPT_Compiler.compile(OPT_Compiler.java:167)
        at VM_BootImageCompiler.compile(VM_BootImageCompiler.java:115)
        at VM_Method.compile(VM_Method.java:332)
        at VM_Class.getInitialInstructions(VM_Class.java:1500)
        at VM_Class.instantiate(VM_Class.java:1326)
        at
BootImageWriter2.createBootImageObjects(BootImageWriter2.java:636)
        at BootImageWriter2.main(BootImageWriter2.java:308)
-----------------------------------------------------------------------

Looking at the assembler support, it seems that this kind of memory
operand (without a base or index register) cannot be assembled.

Does anyone have a quick overview of what I have to do to add this
functionality to the assembler?

-Matthias

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