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At first I'll try the simplest strategy: put the instruction in the machine BB corresponding to the LLVM BB where it comes from. To implement this, I plan to add an operand to non-passive node which points to the BasicBlockSDNode which the node belongs to. Another idea is to use a side map to map each node to its block. But I guess it's difficult to keep the map consistent when transforming the DAG. On Wed, Jun 9, 2010 at 1:39 AM, Dan Gohman <gohman at apple.com> wrote: > The first question is code placement...

I have another idea: let the BasicBlockSDNode points to the last node in its predecessor blocks. But this will introduce cycles into the selection DAG, making it not a DAG anymore. So what's the impact of a non-DAG on the existing DAG legalizers and combiner? On Wed, Jun 9, 2010 at 9:33 AM, Zhongxing Xu <xuzhongxing at gmail.com> w...

On Jun 11, 2010, at 12:48 AM, Zhongxing Xu <xuzhongxing at gmail.com> wrote: > I have another idea: let the BasicBlockSDNode points to the last > node in its predecessor blocks. But this will introduce cycles into > the selection DAG, making it not a DAG anymore. > > So what's the impact of a non-DAG on the existing DAG legalizers and > combiner? Lots of stuff would break, for example anything t...

The first question is code placement. How is the compiler going to decide which block (or blocks) to emit an instruction in? The answer to that will help determine how control relationships should be represented. Dan On Jun 7, 2010, at 11:56 PM, Zhongxing Xu <xuzhongxing at gmail.com> wrote: > I am trying to build a DAG for a whole function. The first problem I > met is to

...uled during instruction scheduling such that they are free to be placed anywhere while generating the instruction sequence. Is this related with above problem of debug location ? The list of passive nodes are :- ConstantSDNode ConstantFPSDNode RegisterSDNode RegisterMaskSDNode GlobalAddressSDNode BasicBlockSDNode FrameIndexSDNode ConstantPoolSDNode JumpTableSDNode ExternalSymbolSDNode BlockAddressSDNode MDNodeSDNode Thanks Karthik -------------- next part -------------- A non-text attachment was scrubbed... Name: gdb11531.s Type: application/octet-stream Size: 10377 bytes Desc: not available URL: <ht...

I am trying to build a DAG for a whole function. The first problem I met is to assign a user for the last instruction of each basic block, be it BRCOND or other node. There is no natural user for such nodes. Without user, it will be removed in later phases. My idea is to use it as chain for nodes in the next basic block. Is this reasonable? -Zhongxing Xu -------------- next part -------------- An