[llvm-commits] [RFC] Patch 1/3 for the native code compiler of Erlang

[Yiannis Tsiouris]

On 05/13/2012 07:51 PM, Jakob Stoklund Olesen wrote:
> On May 13, 2012, at 8:32 AM, Yiannis Tsiouris wrote:
>> Ping.
>>
>> Is there anything wrong with this patch?
> The patch doesn't apply cleanly, possibly because of the missing newline at the end of your test case.
>
> Here you check for a NULL Function:
>
>      const Function *F = MF->getFunction();                                      
>      ghcCall = (F ? F->getCallingConv() == CallingConv::GHC : false);            
> +    hipeCall = (F ? F->getCallingConv() == CallingConv::HiPE : false);          
>
> Here you don't:
>
> +    if (MF.getFunction()->getCallingConv() == CallingConv::HiPE)                
> +      return &X86::GR32RegClass;                                                
>
> /jakob
I attatch an updated patch for the Calling Convention.

However, we noticed one thing. In our our patch we define (among others)
a RetCC for HiPE 64 bit like this:

>+// X86-64 HiPE return-value convention.
>+def RetCC_X86_64_HiPE : CallingConv<[
>+  // Promote all types to i64
>+  CCIfType<[i8, i16, i32], CCPromoteToType<i64>>,
>+
>+  // Return: HP, P, VAL1, VAL2
>+  CCIfType<[i64], CCAssignToReg<[R15, RBP, RAX, RDX]>>
>+]>;

When trying to compile the attatched simple test the CCPromoteToType
attribute doesn't seem to work and the compilation fails with:

yiannist at greg [test/CodeGen/X86]>>= llc < test.ll -mtriple=x86_64-linux
    .file    "<stdin>"
Cannot emit physreg copy instruction
UNREACHABLE executed at X86InstrInfo.cpp:2487!
0  llc             0x0000000001452cb6
1  llc             0x0000000001452ab2
2  libpthread.so.0 0x00007fefd95ae030
3  libc.so.6       0x00007fefd88a7475 gsignal + 53
4  libc.so.6       0x00007fefd88aa6f0 abort + 384
5  llc             0x000000000143d8df
6  llc             0x0000000000cea6f1
llvm::X86InstrInfo::copyPhysReg(llvm::MachineBasicBlock&,
llvm::MachineBasicBlock::bundle_iterator<llvm::MachineInstr,
llvm::ilist_iterator<llvm::MachineInstr> >, llvm::DebugLoc, unsigned
int, unsigned int, bool) const + 1401
7  llc             0x00000000010ae4d1
8  llc             0x00000000010ae895
9  llc             0x0000000000fa1e51
llvm::MachineFunctionPass::runOnFunction(llvm::Function&) + 95
10 llc             0x00000000013e085e
llvm::FPPassManager::runOnFunction(llvm::Function&) + 388
11 llc             0x00000000013e0a79
llvm::FPPassManager::runOnModule(llvm::Module&) + 107
12 llc             0x00000000013e0db9
llvm::MPPassManager::runOnModule(llvm::Module&) + 453
13 llc             0x00000000013e12b9
llvm::PassManagerImpl::run(llvm::Module&) + 125
14 llc             0x00000000013e146d
llvm::PassManager::run(llvm::Module&) + 39
15 llc             0x0000000000842e47 main + 3132
16 libc.so.6       0x00007fefd8893ead __libc_start_main + 253
17 llc             0x0000000000841b59
Stack dump:
0.    Program arguments: llc
1.    Running pass 'Function Pass Manager' on module '<stdin>'.
2.    Running pass 'Post-RA pseudo instruction expansion pass' on
function '@test_nocall_hipecc'
zsh: abort      llc < test.ll


I reproduced the problem by just adding a " CCIfType<[i8, i16, i32],
CCPromoteToType<i64>>," line in RetCC_X86Common in a vanilla LLVM tree
and trying to compile a simple function that uses i32 vregs without a
cc. Is this normal or a bug? I could try to fix it if this is the case.

Changing our RetCC to:

> // X86-64 HiPE return-value convention.
> def RetCC_X86_64_HiPE : CallingConv<[
>-  // Promote all types to i64
>-  CCIfType<[i8, i16, i32], CCPromoteToType<i64>>,
>+  CCIfType<[i8],  CCAssignToReg<[R15B, BPL, AL, DL]>>,
>+  CCIfType<[i16], CCAssignToReg<[R15W, BP, AX, DX]>>,
>+  CCIfType<[i32], CCAssignToReg<[R15D, ESP, EAX, EDX]>>,
>
>   // Return: HP, P, VAL1, VAL2
>   CCIfType<[i64], CCAssignToReg<[R15, RBP, RAX, RDX]>>

seems to work as expected.

Best,
Yiannis

-- 
Yiannis Tsiouris
Ph.D. student,
Software Engineering Laboratory,
National Technical University of Athens
WWW: http://www.softlab.ntua.gr/~gtsiour

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