similar to: [LLVMdev] Inserting MachineBasicBlock(s) before a MachineBasicBlock

Fernando, The code there should be more or less functional, though it's not currently used by anything. Eventually it should probably be moved to a method on MachineBasicBlock. The API breakage you're seeing is because some methods moved around. Feel free to fix it. :-) --Owen On Jan 26, 2008, at 6:31 PM, Fernando Magno Quintao Pereira wrote: > > Hi LLVMers, > >

Hi LLVMers, what is the status of breaking critical edges in machine functions? I just compiled the top of the LLVM tree, and I found llvm/CodeGen/BreakCriticalMachineEdge.h. But this file seems not to be up-to-date with the other classes in the top of the tree. For instance, it calls isTerminatorInstr on llvm::TargetInstrInfo, but this method is no longer there. If I want to break

Hi all, I have a pass to break critical edges of Machine Basic Blocks, but I just discovered a bug (when compiling code for x86). The problem is 'jumpl *%reg'. I don't know how to update the jump table for this type of instruction. The code that I had (see below) does not update the jump table, and the actual branch keeps jumping to the old basic block, instead of the new.

Sorry about the tardiness of my reply. My mail client has playing tricks with me. :-) I am assuming the issue has nothing to do the branch to jumptable instructions but rather the MachineJumpTableInfo associated with every MachineFunction? If so, please take a look at BranchFoldiing.cpp for an example. Evan On Aug 10, 2007, at 12:30 PM, Fernando Magno Quintao Pereira wrote: > >

Thanks, Evan. Actually I've solved my problem with some hints from Dale and Anton. At least I think I've solved it. I had to add one method to TargetInstrInfo to tell me when an instruction is an indirect jump - TargetInstrInfo::tii.isIndirectJump(opcode). When that is the case, I update the jump table using: // Change jumps to go to the new basic block:

Hi, This pass is similar to the one in BreakCriticalEdges.cpp, but it works for MachineFunction's, instead of Functions. The existence of critical edges complicates many optimizations. When doing register allocation, you don't necessarily have to remove critical edges (you can use conventional SSA-form, for instance. See "Translating Out of Static Single Assignment Form. SAS

Dear guys, I am having problem to split edges correctly. Mostly because the new basic blocks are creating infinite loops. Could someone help me fixing the code below? It is creating assembly like this one below. Block LBB1_9 was inserted to break the critical edge between blocks LBB1_3 and LBB1_8. But it changes the semantics of the original program, because, before, LBB1_8 was falling

> If you don't want critical edges in the machine code CFG, you're going to > have to write a machine code CFG critical edge splitting pass: LLVM > doesn't currently have one. > > -Chris Hey guys, I've coded a pass to break the critical edges of the machine control flow graph. The program works fine, but I am sure it is not the right way of implementing it.

On Tue, 4 Jul 2006, Fernando Magno Quintao Pereira wrote: > However, it does not remove all the critical edges. I am getting a very > weird dataflow graph (even without the Break Critical edges pass). The > dataflow generated by MachineFunction::dump() for the program below is > given here: > http://compilers.cs.ucla.edu/fernando/projects/soc/images/loop_no_crit2.pdf ... > The

According to the docs, InsertBranch should only be called if AnalyzeBranch returns success. But in targets (like ARM or Sparc) that don't implement them, the following test fails: ----------------------------------- void %__gcov_init() { entry: switch uint 0, label %cond_true.i [ uint 0, label %UnifiedReturnBlock uint 875573313, label

On Tue, 3 Oct 2006, Fernando Magno Quintao Pereira wrote: > I am having some problems when compiling huge programs (like gcc). > I have a machine pass to destroy critical edges, and I have to add > new basic blocks, but sometimes the program is too big, and the new > basic block gets out of addressing range. What is the proper way to > address this problem? I am producing code

Dear guys, I am having some problems when compiling huge programs (like gcc). I have a machine pass to destroy critical edges, and I have to add new basic blocks, but sometimes the program is too big, and the new basic block gets out of addressing range. What is the proper way to address this problem? I am producing code for the PowerPC, and I had to implement the insert go-to method. I am

Hello, we can get BasicBlock from MachineBasicBlock through MachineBasicBlock::getBasicBlock() function, but how can I get MachineBasicBlock of a BasicBlock? Thank you!

On Aug 17, 2007, at 3:08 PM, Fernando Magno Quintao Pereira wrote: > > Thanks, Evan. > > Actually I've solved my problem with some hints from Dale and > Anton. Ok, cool. I didn't see their replies. Like I said, my email client is acting funny. > At least I think I've solved it. I had to add one method to > TargetInstrInfo to tell me when an instruction

I don't think you can. The BasicBlock is a member of MachineBasicBlock. It is not inherited, so it cannot be cast. The number of the MachineBasicBlock is not the same as any BasicBlock values. So MachineFunction::getMachineBasicBlock( BasicBlock::{get the number} ) cannot work. I do not see much in the basic block which can identify it. So you can search for it. typedef struct findBlock {

Also note: there may be multiple MachineBasicBlock's for a single BasicBlock. - David M On Fri, Oct 15, 2010 at 4:59 AM, Jeff Kunkel <jdkunk3 at gmail.com> wrote: > I don't think you can. > > The BasicBlock is a member of MachineBasicBlock. It is not inherited, > so it cannot be cast. The number of the MachineBasicBlock is not the > same as any BasicBlock values.

Hi All, For various obscure reasons I'd like to detect the condition when X86 CALL instruction immediately precedes a function epilogue in the final emitted code, and insert a NOP between them if that happens. My initial attempt at it looked like this: MachineBasicBlock& MBB; MachineBasicBlock::iterator MBBI; <-- points to where the epilogue would be inserted if (MBBI != MBB.begin()

Hi, guys, I compiled a subroutine with -O2, and llvm backend produced codes like: ################################################################## LBB0_32: ... R31 = -1 R20 = R31 * R20; .... bnz R2, LBB0_34 LBB0_31: ... b LBB0_34 LBB0_33: # weird basic block? R20 = R5 LBB0_34: ....

The problem is that you are inserting block 9 in the wrong spot. mf.getLastBlock() returns the block with the greatest number which may have nothing to do with the ordering. Why not use the end iterator (mf.end) to insert? -Tanya On Sat, 8 Jul 2006, Fernando Magno Quintao Pereira wrote: > > Dear guys, > > I am having problem to split edges correctly. Mostly because the new

Is LiveVariables updated correctly when TII->RemoveBranch and TII->InsertBranch are called in the following piece of code? - MachineBasicBlock::updateTerminator() line 307 of MachineBasicBlock.cpp: if (FBB) { // The block has a non-fallthrough conditional branch. If one of its // successors is its layout successor, rewrite it to a fallthrough // conditional branch.