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

[Evan Cheng]

On Sep 9, 2009, at 11:49 AM, Daniel Dunbar wrote:

> 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?

Only if the system requires it. :-) But yes, we'll need to figure out  
a better way when we want to productize it.

Evan

>
> - 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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