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Hello again. :) There has been renewed interest in having instructions track their own order in basic blocks to help make dominance queries fast. I have a very simple naive implementation of this here: https://reviews.llvm.org/D51664 Essentially, every instruction will carry an integer order number, and inserting new instructions invalidates the ordering. I know there are better algorithms for maintaining the ordering in the face of random insertions, but I wanted to focus on the simple case of making dominance queries amortiz...

...we cache them too much and insert instructions without renumbering the BB, we get miscompiles. My solution is to hook into the actual BB ilist modification methods, so that we can have greater confidence that our cache invalidation is correct. I created a patch for this at https://reviews.llvm.org/D51664, which adds a lazily calculated position integer to every llvm::Instruction. I stole a bit from BasicBlock's Value subclass data to indicate whether the orders are valid. Hopefully everyone agrees that this a reasonable direction. I just figured I should announce this IR data structure change...

...we cache them too much and insert instructions without renumbering the BB, we get miscompiles. My solution is to hook into the actual BB ilist modification methods, so that we can have greater confidence that our cache invalidation is correct. I created a patch for this at https://reviews.llvm.org/D51664, which adds a lazily calculated position integer to every llvm::Instruction. I stole a bit from BasicBlock's Value subclass data to indicate whether the orders are valid. Hopefully everyone agrees that this a reasonable direction. I just figured I should announce this IR data structure change...

...much and insert instructions without renumbering the BB, we get miscompiles. My solution is to hook into the actual BB ilist modification methods, so that we can have greater confidence that our cache invalidation is correct. >> >> I created a patch for this at https://reviews.llvm.org/D51664, which adds a lazily calculated position integer to every llvm::Instruction. I stole a bit from BasicBlock's Value subclass data to indicate whether the orders are valid. >> >> Hopefully everyone agrees that this a reasonable direction. I just figured I should announce this IR data...