[analyzer] Add ipa-always-inline-size option (with 3 as the default).

The option allows to always inline very small functions, whose size (in
number of basic blocks) is set using -analyzer-config
ipa-always-inline-size option.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@163558 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 39 insertions, 7 deletions

diff --git a/lib/StaticAnalyzer/Core/AnalyzerOptions.cpp b/lib/StaticAnalyzer/Core/AnalyzerOptions.cpp
index 29e2783476..5cbbb8d462 100644
--- a/lib/StaticAnalyzer/Core/AnalyzerOptions.cpp
+++ b/lib/StaticAnalyzer/Core/AnalyzerOptions.cpp
@@ -16,6 +16,7 @@
 #include "llvm/ADT/StringSwitch.h"
 
 using namespace clang;
+using namespace llvm;
 
 bool
 AnalyzerOptions::mayInlineCXXMemberFunction(CXXInlineableMemberKind K) const {
@@ -80,3 +81,26 @@ bool AnalyzerOptions::mayInlineTemplateFunctions() const {
   
   return *InlineTemplateFunctions;
 }
+
+int AnalyzerOptions::getOptionAsInteger(StringRef Name, int DefaultVal) const {
+  std::string OptStr = Config.lookup(Name);
+  if (OptStr.empty())
+    return DefaultVal;
+
+  int Res = DefaultVal;
+  assert(StringRef(OptStr).getAsInteger(10, Res) == false &&
+         "analyzer-config option should be numeric.");
+
+  return Res;
+}
+
+unsigned AnalyzerOptions::getAlwaysInlineSize() const {
+  if (!AlwaysInlineSize.hasValue()) {
+    unsigned DefaultSize = 3;
+    Optional<unsigned> &MutableOption =
+      const_cast<Optional<unsigned> &>(AlwaysInlineSize);
+    MutableOption = getOptionAsInteger("ipa-always-inline-size", DefaultSize);
+  }
+
+  return AlwaysInlineSize.getValue();
+}
diff --git a/lib/StaticAnalyzer/Core/ExprEngineCallAndReturn.cpp b/lib/StaticAnalyzer/Core/ExprEngineCallAndReturn.cpp
index 9bf63c5b96..a4e1eb2f4c 100644
--- a/lib/StaticAnalyzer/Core/ExprEngineCallAndReturn.cpp
+++ b/lib/StaticAnalyzer/Core/ExprEngineCallAndReturn.cpp
@@ -247,14 +247,18 @@ void ExprEngine::processCallExit(ExplodedNode *CEBNode) {
   }
 }
 
-static unsigned getNumberStackFrames(const LocationContext *LCtx) {
-  unsigned count = 0;
+static void examineStackFrames(const Decl *D, const LocationContext *LCtx,
+                               bool &IsRecursive, unsigned &StackDepth) {
+  IsRecursive = false;
+  StackDepth = 0;
   while (LCtx) {
-    if (isa<StackFrameContext>(LCtx))
-      ++count;
+    if (const StackFrameContext *SFC = dyn_cast<StackFrameContext>(LCtx)) {
+      ++StackDepth;
+      if (SFC->getDecl() == D)
+        IsRecursive = true;
+    }
     LCtx = LCtx->getParent();
   }
-  return count;  
 }
 
 static bool IsInStdNamespace(const FunctionDecl *FD) {
@@ -282,8 +286,12 @@ bool ExprEngine::shouldInlineDecl(const Decl *D, ExplodedNode *Pred) {
   if (!CalleeCFG)
     return false;
 
-  if (getNumberStackFrames(Pred->getLocationContext())
-        == AMgr.options.InlineMaxStackDepth)
+  bool IsRecursive = false;
+  unsigned StackDepth = 0;
+  examineStackFrames(D, Pred->getLocationContext(), IsRecursive, StackDepth);
+  if ((StackDepth >= AMgr.options.InlineMaxStackDepth) &&
+       ((CalleeCFG->getNumBlockIDs() > AMgr.options.getAlwaysInlineSize())
+         || IsRecursive))
     return false;
 
   if (Engine.FunctionSummaries->hasReachedMaxBlockCount(D))