[LLVMdev] Fix for non-standard variable length array + Visual C X86 specific code

[Reid Spencer]

Morten,

I have committed all your patches except this one. Chris will need to
adjudicate this as changing the allocation can (potentially) change the
behavior and/or performance of the code. 

Patches are here:

http://mail.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20041018/019488.html
http://mail.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20041018/019489.html
http://mail.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20041018/019490.html
http://mail.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20041018/019491.html

Reid.

On Mon, 2004-10-18 at 06:47, Morten Ofstad wrote:
> Paolo Invernizzi wrote:
> 
> > There was a similar problem some time ago, and was resolved with alloca. 
> > I think it's a better solution to use the stack instead of the heap...
> 
> I tend to agree, but the constructors won't get called if it's an object 
> array -- anyway, this particular case there was no objects, just 
> pointers and bools so alloca should be fine. I'll leave it to Chris 
> Lattner to decide if my patch goes in or not...
> 
> To reduce the number of mails, I also include my next patch -- X86 
> specific code and inline assembly for Visual C, unfortunately I had to 
> use the nasty IncludeFile trick again to get the linker to work..
> 
> m.
> 
> 
> 
> ______________________________________________________________________
> Index: lib/Target/X86/X86TargetMachine.cpp
> ===================================================================
> RCS file: /var/cvs/llvm/llvm/lib/Target/X86/X86TargetMachine.cpp,v
> retrieving revision 1.68
> diff -u -r1.68 X86TargetMachine.cpp
> --- lib/Target/X86/X86TargetMachine.cpp	8 Oct 2004 22:41:46 -0000	1.68
> +++ lib/Target/X86/X86TargetMachine.cpp	18 Oct 2004 13:43:52 -0000
> @@ -53,8 +53,10 @@
>    RegisterTarget<X86TargetMachine> X("x86", "  IA-32 (Pentium and above)");
>  }
>  
> +void X86TargetMachine::stub() {}
> +
>  unsigned X86TargetMachine::getJITMatchQuality() {
> -#if defined(i386) || defined(__i386__) || defined(__x86__)
> +#if defined(i386) || defined(__i386__) || defined(__x86__) || defined(_M_IX86)
>    return 10;
>  #else
>    return 0;
> Index: lib/Target/X86/X86TargetMachine.h
> ===================================================================
> RCS file: /var/cvs/llvm/llvm/lib/Target/X86/X86TargetMachine.h,v
> retrieving revision 1.25
> diff -u -r1.25 X86TargetMachine.h
> --- lib/Target/X86/X86TargetMachine.h	11 Jul 2004 02:44:51 -0000	1.25
> +++ lib/Target/X86/X86TargetMachine.h	18 Oct 2004 13:43:52 -0000
> @@ -29,7 +29,7 @@
>    X86JITInfo      JITInfo;
>  public:
>    X86TargetMachine(const Module &M, IntrinsicLowering *IL);
> -
> +  static void stub();
>    virtual const X86InstrInfo     *getInstrInfo() const { return &InstrInfo; }
>    virtual const TargetFrameInfo  *getFrameInfo() const { return &FrameInfo; }
>    virtual       TargetJITInfo    *getJITInfo()         { return &JITInfo; }
> @@ -58,7 +58,8 @@
>                           const X86InstrInfo& ii,
>                           const MachineInstr& MI);
>    }
> -
> +static IncludeFile
> +X86TARGETMACHINE_INCLUDE_FILE((void*)&X86TargetMachine::stub);
>  } // End llvm namespace
>  
>  #endif
> Index: lib/Target/X86/X86CodeEmitter.cpp
> ===================================================================
> RCS file: /var/cvs/llvm/llvm/lib/Target/X86/X86CodeEmitter.cpp,v
> retrieving revision 1.67
> diff -u -r1.67 X86CodeEmitter.cpp
> --- lib/Target/X86/X86CodeEmitter.cpp	17 Oct 2004 07:49:45 -0000	1.67
> +++ lib/Target/X86/X86CodeEmitter.cpp	18 Oct 2004 13:43:53 -0000
> @@ -102,21 +102,34 @@
>    return Stub;
>  }
>  
> +#ifdef _MSC_VER
> +#pragma optimize("y", off)
> +#endif
> +
>  void JITResolver::CompilationCallback() {
> +#ifdef _MSC_VER
> +  unsigned *StackPtr, RetAddr;
> +  __asm mov StackPtr, ebp;
> +  __asm mov eax, DWORD PTR [ebp + 4];
> +  __asm mov RetAddr, eax;
> +#else
>    unsigned *StackPtr = (unsigned*)__builtin_frame_address(0);
>    unsigned RetAddr = (unsigned)(intptr_t)__builtin_return_address(0);
> +#endif
>    assert(StackPtr[1] == RetAddr &&
>           "Could not find return address on the stack!");
>  
>    // It's a stub if there is an interrupt marker after the call...
>    bool isStub = ((unsigned char*)(intptr_t)RetAddr)[0] == 0xCD;
>  
> +#ifndef _MSC_VER
>    // FIXME FIXME FIXME FIXME: __builtin_frame_address doesn't work if frame
>    // pointer elimination has been performed.  Having a variable sized alloca
>    // disables frame pointer elimination currently, even if it's dead.  This is a
>    // gross hack.
>    alloca(10+isStub);
>    // FIXME FIXME FIXME FIXME
> +#endif
>  
>    // The call instruction should have pushed the return value onto the stack...
>    RetAddr -= 4;  // Backtrack to the reference itself...
> @@ -150,6 +163,10 @@
>    StackPtr[1] -= 5;
>  }
>  
> +#ifdef _MSC_VER
> +#pragma optimize( "", on )
> +#endif
> +
>  /// emitStubForFunction - This method is used by the JIT when it needs to emit
>  /// the address of a function for a function whose code has not yet been
>  /// generated.  In order to do this, it generates a stub which jumps to the lazy
> 
> ______________________________________________________________________
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