I just accidently sent a partially complete email, so this contains the
rest (sorry!)
I'm working on translating llvm's optimized intermediate code to another
compiler's intermediate code, and I'm working on the PHI instruction.
Here's an example phi instruction to help explain what I'm trying to do:
%inc25 = phi i32 [ 1, %entry ], [ %inc, %for.body ]
What I would want to do here is allocate some memory memory (i'm trying to
use %phi1 = alloca i32, allign 4 ). Then, I want to go to the %entry block
and say "store i32 1, i32* %phi1", and in the %for.body I want to add
"store i32 1, i32* %phi1".
So first, I'm iterating through my function and basicblock:
int phi = 0;
Function::iterator func_bblock_itr = func->begin();
for(; func_bblock_itr != func->end(); ++func_bblock_itr)
{
BasicBlock::iterator bblock_inst_itr = func_bblock_itr->begin();
for(; bblock_inst_itr != func_bblock_itr->end(); ++bblock_inst_itr)
{
Then, I look for PHI instructions:
if(bblock_inst_itr->getOpcode() == Instruction::PHI) {
If I find one, I allocate space:
string name = "phi";
name.insert(3,to_string(phi));
Twine tname= Twine(name);
AllocaInst alloca
AllocaInst(bblock_inst_itr->getOperand(0)->getType(),tname,func_bblock_itr->begin());
and then i go through the operands one by one to find where to put store
instructions:
for(unsigned int i = 0; i <
bblock_inst_itr->getNumOperands();i++) {
Value *v = bblock_inst_itr->getOperand(i);
Here's where I don't know what to do: I want to create a store
instruction
in that place:
StoreInst(v, alloca?, func_bblock_itr?);
}
}
}
Is this a decent approach to getting the instructions inserted? and what do
I put to get the pointer in the store instruction and the basicblock, the
current code gives me a bunch of errors. Any help would be appreciated,
thanks!
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Hi Ryan, I may be thinking loud here ,You run the reg2mem pass on the optimized IR using opt tool,that will remove the phi dependency in the CFG,. Thanks ~Umesh On Thu, Jul 19, 2012 at 2:37 AM, ryan baird <ryanrbaird at gmail.com> wrote:> I just accidently sent a partially complete email, so this contains the > rest (sorry!) > I'm working on translating llvm's optimized intermediate code to another > compiler's intermediate code, and I'm working on the PHI instruction. > > Here's an example phi instruction to help explain what I'm trying to do: > %inc25 = phi i32 [ 1, %entry ], [ %inc, %for.body ] > > What I would want to do here is allocate some memory memory (i'm trying to > use %phi1 = alloca i32, allign 4 ). Then, I want to go to the %entry block > and say "store i32 1, i32* %phi1", and in the %for.body I want to add > "store i32 1, i32* %phi1". > > So first, I'm iterating through my function and basicblock: > int phi = 0; > Function::iterator func_bblock_itr = func->begin(); > for(; func_bblock_itr != func->end(); ++func_bblock_itr) > { > BasicBlock::iterator bblock_inst_itr = func_bblock_itr->begin(); > for(; bblock_inst_itr != func_bblock_itr->end(); ++bblock_inst_itr) > { > Then, I look for PHI instructions: > if(bblock_inst_itr->getOpcode() == Instruction::PHI) { > If I find one, I allocate space: > string name = "phi"; > name.insert(3,to_string(phi)); > Twine tname= Twine(name); > AllocaInst alloca > AllocaInst(bblock_inst_itr->getOperand(0)->getType(),tname,func_bblock_itr->begin()); > and then i go through the operands one by one to find where to put store > instructions: > for(unsigned int i = 0; i < > bblock_inst_itr->getNumOperands();i++) { > Value *v = bblock_inst_itr->getOperand(i); > Here's where I don't know what to do: I want to create a store instruction > in that place: > StoreInst(v, alloca?, func_bblock_itr?); > } > } > } > > Is this a decent approach to getting the instructions inserted? and what > do I put to get the pointer in the store instruction and the basicblock, > the current code gives me a bunch of errors. Any help would be > appreciated, thanks! > > _______________________________________________ > LLVM Developers mailing list > LLVMdev at cs.uiuc.edu http://llvm.cs.uiuc.edu > http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev > >-------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20120719/27135498/attachment.html>
So, this will generally work, but you actually don't need to write this code at all. If you look in lib/Transforms/Utils/DemoteRegToStack.cpp, there is a function called "DemotePHIToStack" that does exactly what you want to do below. On Wed, Jul 18, 2012 at 2:07 PM, ryan baird <ryanrbaird at gmail.com> wrote:> I just accidently sent a partially complete email, so this contains the rest > (sorry!) > I'm working on translating llvm's optimized intermediate code to another > compiler's intermediate code, and I'm working on the PHI instruction. > > Here's an example phi instruction to help explain what I'm trying to do: > %inc25 = phi i32 [ 1, %entry ], [ %inc, %for.body ] > > What I would want to do here is allocate some memory memory (i'm trying to > use %phi1 = alloca i32, allign 4 ). Then, I want to go to the %entry block > and say "store i32 1, i32* %phi1", and in the %for.body I want to add > "store i32 1, i32* %phi1". > > So first, I'm iterating through my function and basicblock: > int phi = 0; > Function::iterator func_bblock_itr = func->begin(); > for(; func_bblock_itr != func->end(); ++func_bblock_itr) > { > BasicBlock::iterator bblock_inst_itr = func_bblock_itr->begin(); > for(; bblock_inst_itr != func_bblock_itr->end(); ++bblock_inst_itr) > { > Then, I look for PHI instructions: > if(bblock_inst_itr->getOpcode() == Instruction::PHI) { > If I find one, I allocate space: > string name = "phi"; > name.insert(3,to_string(phi)); > Twine tname= Twine(name); > AllocaInst alloca > AllocaInst(bblock_inst_itr->getOperand(0)->getType(),tname,func_bblock_itr->begin()); > and then i go through the operands one by one to find where to put store > instructions: > for(unsigned int i = 0; i < > bblock_inst_itr->getNumOperands();i++) { > Value *v = bblock_inst_itr->getOperand(i); > Here's where I don't know what to do: I want to create a store instruction > in that place: > StoreInst(v, alloca?, func_bblock_itr?); > } > } > } > > Is this a decent approach to getting the instructions inserted? and what do > I put to get the pointer in the store instruction and the basicblock, the > current code gives me a bunch of errors. Any help would be appreciated, > thanks! > > _______________________________________________ > LLVM Developers mailing list > LLVMdev at cs.uiuc.edu http://llvm.cs.uiuc.edu > http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev >