[llvm-commits] [llvm] r81311 - /llvm/trunk/lib/Target/ARM/ARMJITInfo.cpp

[Daniel Dunbar]

Hi Evan,

(insert caveat that I don't understand this stuff here)

This seems like a lot of extra system calls in stub generation, isn't
that potentially pretty bad for performance?

 - Daniel

On Tue, Sep 8, 2009 at 6:56 PM, Evan Cheng<evan.cheng at apple.com> wrote:
> Author: evancheng
> Date: Tue Sep  8 20:56:29 2009
> New Revision: 81311
>
> URL: http://llvm.org/viewvc/llvm-project?rev=81311&view=rev
> Log:
> Make sure to make stub region writable before emission, executable after emission.
>
> Modified:
>    llvm/trunk/lib/Target/ARM/ARMJITInfo.cpp
>
> Modified: llvm/trunk/lib/Target/ARM/ARMJITInfo.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/ARM/ARMJITInfo.cpp?rev=81311&r1=81310&r2=81311&view=diff
>
> ==============================================================================
> --- llvm/trunk/lib/Target/ARM/ARMJITInfo.cpp (original)
> +++ llvm/trunk/lib/Target/ARM/ARMJITInfo.cpp Tue Sep  8 20:56:29 2009
> @@ -140,6 +140,10 @@
>  void *ARMJITInfo::emitGlobalValueIndirectSym(const GlobalValue *GV, void *Ptr,
>                                              JITCodeEmitter &JCE) {
>   JCE.startGVStub(GV, 4, 4);
> +  intptr_t Addr = (intptr_t)JCE.getCurrentPCValue();
> +  if (!sys::Memory::setRangeWritable((void*)Addr, 4)) {
> +    llvm_unreachable("ERROR: Unable to mark indirect symbol writable");
> +  }
>   JCE.emitWordLE((intptr_t)Ptr);
>   void *PtrAddr = JCE.finishGVStub(GV);
>   addIndirectSymAddr(Ptr, (intptr_t)PtrAddr);
> @@ -167,18 +171,30 @@
>       }
>       JCE.startGVStub(F, 16, 4);
>       intptr_t Addr = (intptr_t)JCE.getCurrentPCValue();
> +      if (!sys::Memory::setRangeWritable((void*)Addr, 16)) {
> +        llvm_unreachable("ERROR: Unable to mark stub writable");
> +      }
>       JCE.emitWordLE(0xe59fc004);            // ldr pc, [pc, #+4]
>       JCE.emitWordLE(0xe08fc00c);            // L_func$scv: add ip, pc, ip
>       JCE.emitWordLE(0xe59cf000);            // ldr pc, [ip]
>       JCE.emitWordLE(LazyPtr - (Addr+4+8));  // func - (L_func$scv+8)
>       sys::Memory::InvalidateInstructionCache((void*)Addr, 16);
> +      if (!sys::Memory::setRangeExecutable((void*)Addr, 16)) {
> +        llvm_unreachable("ERROR: Unable to mark stub executable");
> +      }
>     } else {
>       // The stub is 8-byte size and 4-aligned.
>       JCE.startGVStub(F, 8, 4);
>       intptr_t Addr = (intptr_t)JCE.getCurrentPCValue();
> +      if (!sys::Memory::setRangeWritable((void*)Addr, 8)) {
> +        llvm_unreachable("ERROR: Unable to mark stub writable");
> +      }
>       JCE.emitWordLE(0xe51ff004);    // ldr pc, [pc, #-4]
>       JCE.emitWordLE((intptr_t)Fn);  // addr of function
>       sys::Memory::InvalidateInstructionCache((void*)Addr, 8);
> +      if (!sys::Memory::setRangeExecutable((void*)Addr, 8)) {
> +        llvm_unreachable("ERROR: Unable to mark stub executable");
> +      }
>     }
>   } else {
>     // The compilation callback will overwrite the first two words of this
> @@ -190,6 +206,9 @@
>     // The stub is 16-byte size and 4-byte aligned.
>     JCE.startGVStub(F, 16, 4);
>     intptr_t Addr = (intptr_t)JCE.getCurrentPCValue();
> +    if (!sys::Memory::setRangeWritable((void*)Addr, 16)) {
> +      llvm_unreachable("ERROR: Unable to mark stub writable");
> +    }
>     // Save LR so the callback can determine which stub called it.
>     // The compilation callback is responsible for popping this prior
>     // to returning.
> @@ -201,6 +220,9 @@
>     // The address of the compilation callback.
>     JCE.emitWordLE((intptr_t)ARMCompilationCallback);
>     sys::Memory::InvalidateInstructionCache((void*)Addr, 16);
> +    if (!sys::Memory::setRangeExecutable((void*)Addr, 16)) {
> +      llvm_unreachable("ERROR: Unable to mark stub executable");
> +    }
>   }
>
>   return JCE.finishGVStub(F);
>
>
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