[cfe-commits] r116696 - in /cfe/trunk: lib/CodeGen/TargetInfo.cpp test/CodeGen/x86_32-arguments-darwin.c test/CodeGen/x86_32-arguments-linux.c

[Bill Wendling]

On Oct 18, 2010, at 4:16 PM, Daniel Dunbar wrote:

> Hi Bill,
> 
> On Sun, Oct 17, 2010 at 8:41 PM, Bill Wendling <isanbard at gmail.com> wrote:
>> Author: void
>> Date: Sun Oct 17 22:41:31 2010
>> New Revision: 116696
>> 
>> URL: http://llvm.org/viewvc/llvm-project?rev=116696&view=rev
>> Log:
>> Reapply r116684 with fixes. The test cases needed to be updated.
> 
> I like the general approach, but I don't think any of the changes to
> propagate neededMMX are, err, needed. Actually, I think they are wrong
> because we won't stop using registers for varargs at the right point
> any more unless I am misreading things.
> 
I was wondering that too. I think it's useful in this part:

>> @@ -1787,7 +1817,7 @@
>>   FI.getReturnInfo() = classifyReturnType(FI.getReturnType());
>> 
>>   // Keep track of the number of assigned registers.
>> -  unsigned freeIntRegs = 6, freeSSERegs = 8;
>> +  unsigned freeIntRegs = 6, freeSSERegs = 8, freeMMXRegs = 8;
>> 
>>   // If the return value is indirect, then the hidden argument is consuming one
>>   // integer register.
>> @@ -1798,16 +1828,18 @@
>>   // get assigned (in left-to-right order) for passing as follows...
>>   for (CGFunctionInfo::arg_iterator it = FI.arg_begin(), ie = FI.arg_end();
>>        it != ie; ++it) {
>> -    unsigned neededInt, neededSSE;
>> -    it->info = classifyArgumentType(it->type, neededInt, neededSSE);
>> +    unsigned neededInt, neededSSE, neededMMX;
>> +    it->info = classifyArgumentType(it->type, neededInt, neededSSE, neededMMX);
>> 
>>     // AMD64-ABI 3.2.3p3: If there are no registers available for any
>>     // eightbyte of an argument, the whole argument is passed on the
>>     // stack. If registers have already been assigned for some
>>     // eightbytes of such an argument, the assignments get reverted.
>> -    if (freeIntRegs >= neededInt && freeSSERegs >= neededSSE) {
>> +    if (freeIntRegs >= neededInt && freeSSERegs >= neededSSE &&
>> +        freeMMXRegs >= neededMMX) {
>>       freeIntRegs -= neededInt;
>>       freeSSERegs -= neededSSE;
>> +      freeMMXRegs -= neededMMX;
>>     } else {
>>       it->info = getIndirectResult(it->type);
>>     }

But it was this part that I was unsure about, so I made it and neededSSE equivalent:

>> @@ -1876,10 +1908,13 @@
>>   //   i8* overflow_arg_area;
>>   //   i8* reg_save_area;
>>   // };
>> -  unsigned neededInt, neededSSE;
>> +  unsigned neededInt, neededSSE, neededMMX;
>> 
>>   Ty = CGF.getContext().getCanonicalType(Ty);
>> -  ABIArgInfo AI = classifyArgumentType(Ty, neededInt, neededSSE);
>> +  ABIArgInfo AI = classifyArgumentType(Ty, neededInt, neededSSE, neededMMX);
>> +
>> +  // Lump the MMX in with SSE.
>> +  neededSSE += neededMMX;
>> 
>>   // AMD64-ABI 3.5.7p5: Step 1. Determine whether type may be passed
>>   // in the registers. If not go to step 7.

Basically, the variable then comes down to use in X86_64ABIInfo::computeInfo...

-bw