Kristóf Umann via llvm-dev
2019-Jun-03 23:51 UTC
[llvm-dev] [IDF][analyzer] Generalizing IDFCalculator to be used for Clang's CFG
Hi! As the title suggests, I'd like to generalize llvm::IDFCalculator to be able to calculate control dependencies on clang's CFG. The issue is however, that many data structures it uses are "hardcoded" to use llvm::BasicBlock, and requires a lot of code to turn it into template arguments. I managed to pull this off by hammering the code until it compiled, and it works perfectly, but I'm not really happy with how the patch came out: https://github.com/Szelethus/llvm-project/compare/domtree_unittest...Szelethus:control_dependency?expand=1 Sadly, my knowledge on LLVM IR and phi nodes in general is very limited. My questions are: 1. I read the article IDFCalculator is based on[1], but I found no references to IDFCalculator::setLiveInBlocks, and the file header seems to confirm that it's an implementation specific thing. Could I get away restricting the clang::CFG tailored version to not contain this function? 2. I didn't really manage to understand the logic for GraphDiff. What does it really do in IDFCalculator's context? I dag out the patch[2] that added an extra constructor to use a snapshot of the CFG, but it seems to be unused. Is it also unlikely that we find any use for this? Mind you, the patch size grew a lot because I also "templatized" GraphDiff and all related classes to handle clang's CFG. If the answer to both of these questions is "no", I'd separate out a base of IDFCalculator, to a new class called IDFCalculatorBase that wouldn't contain either of said functions. Cheers! Kristóf [1] Sreedhar, Vugranam C., and Guang R. Gao. "A linear time algorithm for placing ϕ-nodes." Proceedings of the 22nd ACM SIGPLAN-SIGACT symposium on Principles of programming languages. ACM, 1995. [2] [IDF] Teach Iterated Dominance Frontier to use a snapshot CFG based on a GraphDiff. https://reviews.llvm.org/D50675 -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20190604/66ac16d0/attachment.html>
Kristóf Umann via llvm-dev
2019-Jun-08 19:21 UTC
[llvm-dev] [IDF][analyzer] Generalizing IDFCalculator to be used for Clang's CFG
A polite ping on this matter :) On Tue, 4 Jun 2019 at 01:51, Kristóf Umann <dkszelethus at gmail.com> wrote:> Hi! > > As the title suggests, I'd like to generalize llvm::IDFCalculator to be > able to calculate control dependencies on clang's CFG. The issue is > however, that many data structures it uses are "hardcoded" to use > llvm::BasicBlock, and requires a lot of code to turn it into template > arguments. > > I managed to pull this off by hammering the code until it compiled, and it > works perfectly, but I'm not really happy with how the patch came out: > > https://github.com/Szelethus/llvm-project/compare/domtree_unittest...Szelethus:control_dependency?expand=1 > > Sadly, my knowledge on LLVM IR and phi nodes in general is very limited. > My questions are: > > 1. I read the article IDFCalculator is based on[1], but I found no > references to IDFCalculator::setLiveInBlocks, and the file header seems to > confirm that it's an implementation specific thing. Could I get away > restricting the clang::CFG tailored version to not contain this function? > > 2. I didn't really manage to understand the logic for GraphDiff. What does > it really do in IDFCalculator's context? I dag out the patch[2] that added > an extra constructor to use a snapshot of the CFG, but it seems to be > unused. Is it also unlikely that we find any use for this? Mind you, the > patch size grew a lot because I also "templatized" GraphDiff and all > related classes to handle clang's CFG. > > If the answer to both of these questions is "no", I'd separate out a base > of IDFCalculator, to a new class called IDFCalculatorBase that wouldn't > contain either of said functions. > > Cheers! > Kristóf > > > [1] Sreedhar, Vugranam C., and Guang R. Gao. "A linear time algorithm for > placing ϕ-nodes." Proceedings of the 22nd ACM SIGPLAN-SIGACT symposium on > Principles of programming languages. ACM, 1995. > [2] [IDF] Teach Iterated Dominance Frontier to use a snapshot CFG based on > a GraphDiff. https://reviews.llvm.org/D50675 >-------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20190608/27cc4103/attachment.html>
Kristóf Umann via llvm-dev
2019-Jun-16 14:55 UTC
[llvm-dev] [IDF][analyzer] Generalizing IDFCalculator to be used for Clang's CFG
A polite ping, could someone please share a thought about this? On Sat, 8 Jun 2019 at 21:21, Kristóf Umann <dkszelethus at gmail.com> wrote:> A polite ping on this matter :) > > On Tue, 4 Jun 2019 at 01:51, Kristóf Umann <dkszelethus at gmail.com> wrote: > >> Hi! >> >> As the title suggests, I'd like to generalize llvm::IDFCalculator to be >> able to calculate control dependencies on clang's CFG. The issue is >> however, that many data structures it uses are "hardcoded" to use >> llvm::BasicBlock, and requires a lot of code to turn it into template >> arguments. >> >> I managed to pull this off by hammering the code until it compiled, and >> it works perfectly, but I'm not really happy with how the patch came out: >> >> https://github.com/Szelethus/llvm-project/compare/domtree_unittest...Szelethus:control_dependency?expand=1 >> >> Sadly, my knowledge on LLVM IR and phi nodes in general is very limited. >> My questions are: >> >> 1. I read the article IDFCalculator is based on[1], but I found no >> references to IDFCalculator::setLiveInBlocks, and the file header seems to >> confirm that it's an implementation specific thing. Could I get away >> restricting the clang::CFG tailored version to not contain this function? >> >> 2. I didn't really manage to understand the logic for GraphDiff. What >> does it really do in IDFCalculator's context? I dag out the patch[2] that >> added an extra constructor to use a snapshot of the CFG, but it seems to be >> unused. Is it also unlikely that we find any use for this? Mind you, the >> patch size grew a lot because I also "templatized" GraphDiff and all >> related classes to handle clang's CFG. >> >> If the answer to both of these questions is "no", I'd separate out a base >> of IDFCalculator, to a new class called IDFCalculatorBase that wouldn't >> contain either of said functions. >> >> Cheers! >> Kristóf >> >> >> [1] Sreedhar, Vugranam C., and Guang R. Gao. "A linear time algorithm for >> placing ϕ-nodes." Proceedings of the 22nd ACM SIGPLAN-SIGACT symposium on >> Principles of programming languages. ACM, 1995. >> [2] [IDF] Teach Iterated Dominance Frontier to use a snapshot CFG based >> on a GraphDiff. https://reviews.llvm.org/D50675 >> >-------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20190616/4c9cfdfb/attachment.html>
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