Re: basic bloc chaining: using dominance
On Wed, May 11, 2011 at 10:03 PM, Ian Lance Taylor i...@google.com wrote: Pierre Vittet pier...@pvittet.com writes: First, thanks for your help. I have looked at several function using calculate_dominance_info(). From what I understand, when you have finish to use it, you have to clear the structure by making a free_dominance_info(). In the function flow_loops_find (file gcc/cfgloop.c), there is a call to calculate_dominance_info() without call to free_dominance_info(). I feel it is a bug, no? Not in this case, no. The caller or a later pass is responsible for freeing it in this case. There should ideally be a comment about this. dominator information should be freed if it is made invalid by CFG transformations. Otherwise the policy is to keep it around to avoid re-computing it (too many passes need it). For post-dominator info the policy is to always free it. Richard. Ian
Re: basic bloc chaining: using dominance
On 10/05/2011 16:23, Ian Lance Taylor wrote: Pierre Vittetpier...@pvittet.com writes: I am working on a plugin at the GIMPLE state, I am parsing basic blocks and I need to check that a call to foo() is only present once in a function. Howerver, it can be present several times if it is in different basic blocks and only one is executed at execution time. I think the most convenient way is to use dominance relation between the basic blocks: I can warn in a basic block A calling the foo() function only if there is a block B calling foo and dominating A. In others cases, I cannot be sure that there is several calls to foo(). In the file gcc/dominance.c, there is a dominated_by_p function which allows to test dominance between 2 basic blocks and I would like to use it to solve this problem. I would like to have your opinion, does it looks the google solution to the problem or is there another way to do this? If this is a good solution, I will implement a primitive in MELT allowing to use dominated_by_p function in MELT. Yes, dominated_by_p and friends are the right way to test for basic block dominance. Note that you have to build the graph first; see uses of calculate_dominance_info. Ian First, thanks for your help. I have looked at several function using calculate_dominance_info(). From what I understand, when you have finish to use it, you have to clear the structure by making a free_dominance_info(). In the function flow_loops_find (file gcc/cfgloop.c), there is a call to calculate_dominance_info() without call to free_dominance_info(). I feel it is a bug, no?
Re: basic bloc chaining: using dominance
Pierre Vittet pier...@pvittet.com writes: First, thanks for your help. I have looked at several function using calculate_dominance_info(). From what I understand, when you have finish to use it, you have to clear the structure by making a free_dominance_info(). In the function flow_loops_find (file gcc/cfgloop.c), there is a call to calculate_dominance_info() without call to free_dominance_info(). I feel it is a bug, no? Not in this case, no. The caller or a later pass is responsible for freeing it in this case. There should ideally be a comment about this. Ian
basic bloc chaining: using dominance
Hello, I am working on a plugin at the GIMPLE state, I am parsing basic blocks and I need to check that a call to foo() is only present once in a function. Howerver, it can be present several times if it is in different basic blocks and only one is executed at execution time. I think the most convenient way is to use dominance relation between the basic blocks: I can warn in a basic block A calling the foo() function only if there is a block B calling foo and dominating A. In others cases, I cannot be sure that there is several calls to foo(). In the file gcc/dominance.c, there is a dominated_by_p function which allows to test dominance between 2 basic blocks and I would like to use it to solve this problem. I would like to have your opinion, does it looks the google solution to the problem or is there another way to do this? If this is a good solution, I will implement a primitive in MELT allowing to use dominated_by_p function in MELT. Thanks! Pierre Vittet My Google Summer Of Code projet: http://www.google-melange.com/gsoc/project/google/gsoc2011/piervit/15001
Re: basic bloc chaining: using dominance
Pierre Vittet pier...@pvittet.com writes: I am working on a plugin at the GIMPLE state, I am parsing basic blocks and I need to check that a call to foo() is only present once in a function. Howerver, it can be present several times if it is in different basic blocks and only one is executed at execution time. I think the most convenient way is to use dominance relation between the basic blocks: I can warn in a basic block A calling the foo() function only if there is a block B calling foo and dominating A. In others cases, I cannot be sure that there is several calls to foo(). In the file gcc/dominance.c, there is a dominated_by_p function which allows to test dominance between 2 basic blocks and I would like to use it to solve this problem. I would like to have your opinion, does it looks the google solution to the problem or is there another way to do this? If this is a good solution, I will implement a primitive in MELT allowing to use dominated_by_p function in MELT. Yes, dominated_by_p and friends are the right way to test for basic block dominance. Note that you have to build the graph first; see uses of calculate_dominance_info. Ian
