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+/*============================================================================
+ CMake - Cross Platform Makefile Generator
+ Copyright 2000-2009 Kitware, Inc., Insight Software Consortium
+
+ Distributed under the OSI-approved BSD License (the "License");
+ see accompanying file Copyright.txt for details.
+
+ This software is distributed WITHOUT ANY WARRANTY; without even the
+ implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+ See the License for more information.
+============================================================================*/
+#include "cmComputeTargetDepends.h"
+
+#include "cmComputeComponentGraph.h"
+#include "cmGlobalGenerator.h"
+#include "cmLocalGenerator.h"
+#include "cmMakefile.h"
+#include "cmSystemTools.h"
+#include "cmTarget.h"
+#include "cmake.h"
+
+#include <algorithm>
+
+#include <assert.h>
+
+/*
+
+This class is meant to analyze inter-target dependencies globally
+during the generation step. The goal is to produce a set of direct
+dependencies for each target such that no cycles are left and the
+build order is safe.
+
+For most target types cyclic dependencies are not allowed. However
+STATIC libraries may depend on each other in a cyclic fashion. In
+general the directed dependency graph forms a directed-acyclic-graph
+of strongly connected components. All strongly connected components
+should consist of only STATIC_LIBRARY targets.
+
+In order to safely break dependency cycles we must preserve all other
+dependencies passing through the corresponding strongly connected component.
+The approach taken by this class is as follows:
+
+ - Collect all targets and form the original dependency graph
+ - Run Tarjan's algorithm to extract the strongly connected components
+ (error if any member of a non-trivial component is not STATIC)
+ - The original dependencies imply a DAG on the components.
+ Use the implied DAG to construct a final safe set of dependencies.
+
+The final dependency set is constructed as follows:
+
+ - For each connected component targets are placed in an arbitrary
+ order. Each target depends on the target following it in the order.
+ The first target is designated the head and the last target the tail.
+ (most components will be just 1 target anyway)
+
+ - Original dependencies between targets in different components are
+ converted to connect the depender's component tail to the
+ dependee's component head.
+
+In most cases this will reproduce the original dependencies. However
+when there are cycles of static libraries they will be broken in a
+safe manner.
+
+For example, consider targets A0, A1, A2, B0, B1, B2, and C with these
+dependencies:
+
+ A0 -> A1 -> A2 -> A0 , B0 -> B1 -> B2 -> B0 -> A0 , C -> B0
+
+Components may be identified as
+
+ Component 0: A0, A1, A2
+ Component 1: B0, B1, B2
+ Component 2: C
+
+Intra-component dependencies are:
+
+ 0: A0 -> A1 -> A2 , head=A0, tail=A2
+ 1: B0 -> B1 -> B2 , head=B0, tail=B2
+ 2: head=C, tail=C
+
+The inter-component dependencies are converted as:
+
+ B0 -> A0 is component 1->0 and becomes B2 -> A0
+ C -> B0 is component 2->1 and becomes C -> B0
+
+This leads to the final target dependencies:
+
+ C -> B0 -> B1 -> B2 -> A0 -> A1 -> A2
+
+These produce a safe build order since C depends directly or
+transitively on all the static libraries it links.
+
+*/
+
+//----------------------------------------------------------------------------
+cmComputeTargetDepends::cmComputeTargetDepends(cmGlobalGenerator* gg)
+{
+ this->GlobalGenerator = gg;
+ cmake* cm = this->GlobalGenerator->GetCMakeInstance();
+ this->DebugMode = cm->GetPropertyAsBool("GLOBAL_DEPENDS_DEBUG_MODE");
+ this->NoCycles = cm->GetPropertyAsBool("GLOBAL_DEPENDS_NO_CYCLES");
+}
+
+//----------------------------------------------------------------------------
+cmComputeTargetDepends::~cmComputeTargetDepends()
+{
+}
+
+//----------------------------------------------------------------------------
+bool cmComputeTargetDepends::Compute()
+{
+ // Build the original graph.
+ this->CollectTargets();
+ this->CollectDepends();
+ if(this->DebugMode)
+ {
+ this->DisplayGraph(this->InitialGraph, "initial");
+ }
+
+ // Identify components.
+ cmComputeComponentGraph ccg(this->InitialGraph);
+ if(this->DebugMode)
+ {
+ this->DisplayComponents(ccg);
+ }
+ if(!this->CheckComponents(ccg))
+ {
+ return false;
+ }
+
+ // Compute the final dependency graph.
+ if(!this->ComputeFinalDepends(ccg))
+ {
+ return false;
+ }
+ if(this->DebugMode)
+ {
+ this->DisplayGraph(this->FinalGraph, "final");
+ }
+
+ return true;
+}
+
+//----------------------------------------------------------------------------
+void
+cmComputeTargetDepends::GetTargetDirectDepends(cmTarget* t,
+ cmTargetDependSet& deps)
+{
+ // Lookup the index for this target. All targets should be known by
+ // this point.
+ std::map<cmTarget*, int>::const_iterator tii = this->TargetIndex.find(t);
+ assert(tii != this->TargetIndex.end());
+ int i = tii->second;
+
+ // Get its final dependencies.
+ EdgeList const& nl = this->FinalGraph[i];
+ for(EdgeList::const_iterator ni = nl.begin(); ni != nl.end(); ++ni)
+ {
+ cmTarget* dep = this->Targets[*ni];
+ cmTargetDependSet::iterator di = deps.insert(dep).first;
+ di->SetType(ni->IsStrong());
+ }
+}
+
+//----------------------------------------------------------------------------
+void cmComputeTargetDepends::CollectTargets()
+{
+ // Collect all targets from all generators.
+ std::vector<cmLocalGenerator*> const& lgens =
+ this->GlobalGenerator->GetLocalGenerators();
+ for(unsigned int i = 0; i < lgens.size(); ++i)
+ {
+ cmTargets& targets = lgens[i]->GetMakefile()->GetTargets();
+ for(cmTargets::iterator ti = targets.begin(); ti != targets.end(); ++ti)
+ {
+ cmTarget* target = &ti->second;
+ int index = static_cast<int>(this->Targets.size());
+ this->TargetIndex[target] = index;
+ this->Targets.push_back(target);
+ }
+ }
+}
+
+//----------------------------------------------------------------------------
+void cmComputeTargetDepends::CollectDepends()
+{
+ // Allocate the dependency graph adjacency lists.
+ this->InitialGraph.resize(this->Targets.size());
+
+ // Compute each dependency list.
+ for(unsigned int i=0; i < this->Targets.size(); ++i)
+ {
+ this->CollectTargetDepends(i);
+ }
+}
+
+//----------------------------------------------------------------------------
+void cmComputeTargetDepends::CollectTargetDepends(int depender_index)
+{
+ // Get the depender.
+ cmTarget* depender = this->Targets[depender_index];
+
+ // Loop over all targets linked directly.
+ {
+ cmTarget::LinkLibraryVectorType const& tlibs =
+ depender->GetOriginalLinkLibraries();
+ std::set<cmStdString> emitted;
+ // A target should not depend on itself.
+ emitted.insert(depender->GetName());
+ for(cmTarget::LinkLibraryVectorType::const_iterator lib = tlibs.begin();
+ lib != tlibs.end(); ++lib)
+ {
+ // Don't emit the same library twice for this target.
+ if(emitted.insert(lib->first).second)
+ {
+ this->AddTargetDepend(depender_index, lib->first.c_str(), true);
+ }
+ }
+ }
+
+ // Loop over all utility dependencies.
+ {
+ std::set<cmStdString> const& tutils = depender->GetUtilities();
+ std::set<cmStdString> emitted;
+ // A target should not depend on itself.
+ emitted.insert(depender->GetName());
+ for(std::set<cmStdString>::const_iterator util = tutils.begin();
+ util != tutils.end(); ++util)
+ {
+ // Don't emit the same utility twice for this target.
+ if(emitted.insert(*util).second)
+ {
+ this->AddTargetDepend(depender_index, util->c_str(), false);
+ }
+ }
+ }
+}
+
+//----------------------------------------------------------------------------
+void cmComputeTargetDepends::AddTargetDepend(int depender_index,
+ const char* dependee_name,
+ bool linking)
+{
+ // Get the depender.
+ cmTarget* depender = this->Targets[depender_index];
+
+ // Check the target's makefile first.
+ cmTarget* dependee =
+ depender->GetMakefile()->FindTargetToUse(dependee_name);
+
+ // Skip targets that will not really be linked. This is probably a
+ // name conflict between an external library and an executable
+ // within the project.
+ if(linking && dependee &&
+ dependee->GetType() == cmTarget::EXECUTABLE &&
+ !dependee->IsExecutableWithExports())
+ {
+ dependee = 0;
+ }
+
+ if(dependee)
+ {
+ this->AddTargetDepend(depender_index, dependee, linking);
+ }
+}
+
+//----------------------------------------------------------------------------
+void cmComputeTargetDepends::AddTargetDepend(int depender_index,
+ cmTarget* dependee,
+ bool linking)
+{
+ if(dependee->IsImported())
+ {
+ // Skip imported targets but follow their utility dependencies.
+ std::set<cmStdString> const& utils = dependee->GetUtilities();
+ for(std::set<cmStdString>::const_iterator i = utils.begin();
+ i != utils.end(); ++i)
+ {
+ if(cmTarget* transitive_dependee =
+ dependee->GetMakefile()->FindTargetToUse(i->c_str()))
+ {
+ this->AddTargetDepend(depender_index, transitive_dependee, false);
+ }
+ }
+ }
+ else
+ {
+ // Lookup the index for this target. All targets should be known by
+ // this point.
+ std::map<cmTarget*, int>::const_iterator tii =
+ this->TargetIndex.find(dependee);
+ assert(tii != this->TargetIndex.end());
+ int dependee_index = tii->second;
+
+ // Add this entry to the dependency graph.
+ this->InitialGraph[depender_index].push_back(
+ cmGraphEdge(dependee_index, !linking));
+ }
+}
+
+//----------------------------------------------------------------------------
+void
+cmComputeTargetDepends::DisplayGraph(Graph const& graph, const char* name)
+{
+ fprintf(stderr, "The %s target dependency graph is:\n", name);
+ int n = static_cast<int>(graph.size());
+ for(int depender_index = 0; depender_index < n; ++depender_index)
+ {
+ EdgeList const& nl = graph[depender_index];
+ cmTarget* depender = this->Targets[depender_index];
+ fprintf(stderr, "target %d is [%s]\n",
+ depender_index, depender->GetName());
+ for(EdgeList::const_iterator ni = nl.begin(); ni != nl.end(); ++ni)
+ {
+ int dependee_index = *ni;
+ cmTarget* dependee = this->Targets[dependee_index];
+ fprintf(stderr, " depends on target %d [%s] (%s)\n", dependee_index,
+ dependee->GetName(), ni->IsStrong()? "strong" : "weak");
+ }
+ }
+ fprintf(stderr, "\n");
+}
+
+//----------------------------------------------------------------------------
+void
+cmComputeTargetDepends
+::DisplayComponents(cmComputeComponentGraph const& ccg)
+{
+ fprintf(stderr, "The strongly connected components are:\n");
+ std::vector<NodeList> const& components = ccg.GetComponents();
+ int n = static_cast<int>(components.size());
+ for(int c = 0; c < n; ++c)
+ {
+ NodeList const& nl = components[c];
+ fprintf(stderr, "Component (%d):\n", c);
+ for(NodeList::const_iterator ni = nl.begin(); ni != nl.end(); ++ni)
+ {
+ int i = *ni;
+ fprintf(stderr, " contains target %d [%s]\n",
+ i, this->Targets[i]->GetName());
+ }
+ }
+ fprintf(stderr, "\n");
+}
+
+//----------------------------------------------------------------------------
+bool
+cmComputeTargetDepends
+::CheckComponents(cmComputeComponentGraph const& ccg)
+{
+ // All non-trivial components should consist only of static
+ // libraries.
+ std::vector<NodeList> const& components = ccg.GetComponents();
+ int nc = static_cast<int>(components.size());
+ for(int c=0; c < nc; ++c)
+ {
+ // Get the current component.
+ NodeList const& nl = components[c];
+
+ // Skip trivial components.
+ if(nl.size() < 2)
+ {
+ continue;
+ }
+
+ // Immediately complain if no cycles are allowed at all.
+ if(this->NoCycles)
+ {
+ this->ComplainAboutBadComponent(ccg, c);
+ return false;
+ }
+
+ // Make sure the component is all STATIC_LIBRARY targets.
+ for(NodeList::const_iterator ni = nl.begin(); ni != nl.end(); ++ni)
+ {
+ if(this->Targets[*ni]->GetType() != cmTarget::STATIC_LIBRARY)
+ {
+ this->ComplainAboutBadComponent(ccg, c);
+ return false;
+ }
+ }
+ }
+ return true;
+}
+
+//----------------------------------------------------------------------------
+void
+cmComputeTargetDepends
+::ComplainAboutBadComponent(cmComputeComponentGraph const& ccg, int c,
+ bool strong)
+{
+ // Construct the error message.
+ cmOStringStream e;
+ e << "The inter-target dependency graph contains the following "
+ << "strongly connected component (cycle):\n";
+ std::vector<NodeList> const& components = ccg.GetComponents();
+ std::vector<int> const& cmap = ccg.GetComponentMap();
+ NodeList const& cl = components[c];
+ for(NodeList::const_iterator ci = cl.begin(); ci != cl.end(); ++ci)
+ {
+ // Get the depender.
+ int i = *ci;
+ cmTarget* depender = this->Targets[i];
+
+ // Describe the depender.
+ e << " \"" << depender->GetName() << "\" of type "
+ << cmTarget::GetTargetTypeName(depender->GetType()) << "\n";
+
+ // List its dependencies that are inside the component.
+ EdgeList const& nl = this->InitialGraph[i];
+ for(EdgeList::const_iterator ni = nl.begin(); ni != nl.end(); ++ni)
+ {
+ int j = *ni;
+ if(cmap[j] == c)
+ {
+ cmTarget* dependee = this->Targets[j];
+ e << " depends on \"" << dependee->GetName() << "\""
+ << " (" << (ni->IsStrong()? "strong" : "weak") << ")\n";
+ }
+ }
+ }
+ if(strong)
+ {
+ // Custom command executable dependencies cannot occur within a
+ // component of static libraries. The cycle must appear in calls
+ // to add_dependencies.
+ e << "The component contains at least one cycle consisting of strong "
+ << "dependencies (created by add_dependencies) that cannot be broken.";
+ }
+ else if(this->NoCycles)
+ {
+ e << "The GLOBAL_DEPENDS_NO_CYCLES global property is enabled, so "
+ << "cyclic dependencies are not allowed even among static libraries.";
+ }
+ else
+ {
+ e << "At least one of these targets is not a STATIC_LIBRARY. "
+ << "Cyclic dependencies are allowed only among static libraries.";
+ }
+ cmSystemTools::Error(e.str().c_str());
+}
+
+//----------------------------------------------------------------------------
+bool
+cmComputeTargetDepends
+::IntraComponent(std::vector<int> const& cmap, int c, int i, int* head,
+ std::set<int>& emitted, std::set<int>& visited)
+{
+ if(!visited.insert(i).second)
+ {
+ // Cycle in utility depends!
+ return false;
+ }
+ if(emitted.insert(i).second)
+ {
+ // Honor strong intra-component edges in the final order.
+ EdgeList const& el = this->InitialGraph[i];
+ for(EdgeList::const_iterator ei = el.begin(); ei != el.end(); ++ei)
+ {
+ int j = *ei;
+ if(cmap[j] == c && ei->IsStrong())
+ {
+ this->FinalGraph[i].push_back(cmGraphEdge(j, true));
+ if(!this->IntraComponent(cmap, c, j, head, emitted, visited))
+ {
+ return false;
+ }
+ }
+ }
+
+ // Prepend to a linear linked-list of intra-component edges.
+ if(*head >= 0)
+ {
+ this->FinalGraph[i].push_back(cmGraphEdge(*head, false));
+ }
+ else
+ {
+ this->ComponentTail[c] = i;
+ }
+ *head = i;
+ }
+ return true;
+}
+
+//----------------------------------------------------------------------------
+bool
+cmComputeTargetDepends
+::ComputeFinalDepends(cmComputeComponentGraph const& ccg)
+{
+ // Get the component graph information.
+ std::vector<NodeList> const& components = ccg.GetComponents();
+ Graph const& cgraph = ccg.GetComponentGraph();
+
+ // Allocate the final graph.
+ this->FinalGraph.resize(0);
+ this->FinalGraph.resize(this->InitialGraph.size());
+
+ // Choose intra-component edges to linearize dependencies.
+ std::vector<int> const& cmap = ccg.GetComponentMap();
+ this->ComponentHead.resize(components.size());
+ this->ComponentTail.resize(components.size());
+ int nc = static_cast<int>(components.size());
+ for(int c=0; c < nc; ++c)
+ {
+ int head = -1;
+ std::set<int> emitted;
+ NodeList const& nl = components[c];
+ for(NodeList::const_reverse_iterator ni = nl.rbegin();
+ ni != nl.rend(); ++ni)
+ {
+ std::set<int> visited;
+ if(!this->IntraComponent(cmap, c, *ni, &head, emitted, visited))
+ {
+ // Cycle in add_dependencies within component!
+ this->ComplainAboutBadComponent(ccg, c, true);
+ return false;
+ }
+ }
+ this->ComponentHead[c] = head;
+ }
+
+ // Convert inter-component edges to connect component tails to heads.
+ int n = static_cast<int>(cgraph.size());
+ for(int depender_component=0; depender_component < n; ++depender_component)
+ {
+ int depender_component_tail = this->ComponentTail[depender_component];
+ EdgeList const& nl = cgraph[depender_component];
+ for(EdgeList::const_iterator ni = nl.begin(); ni != nl.end(); ++ni)
+ {
+ int dependee_component = *ni;
+ int dependee_component_head = this->ComponentHead[dependee_component];
+ this->FinalGraph[depender_component_tail]
+ .push_back(cmGraphEdge(dependee_component_head, ni->IsStrong()));
+ }
+ }
+ return true;
+}