[INLINER] allow inlining of address taken blocks

as long as their uses does not contain calls to functions that capture
the argument (potentially allowing the blockaddress to "escape" the
lifetime of the caller).

TODO:
- add more tests
- fix crash in llvm::updateCGAndAnalysisManagerForFunctionPass when
  invoking Transforms/Inline/blockaddress.ll

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@354079 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/include/llvm/IR/BasicBlock.h b/include/llvm/IR/BasicBlock.h
index fd9efb8417ea9a7fe27bea4473e9e6251fd6c825..076adad7cf73ec1ad06ace2b3fa81b6cb9a00654 100644 (file)
--- a/include/llvm/IR/BasicBlock.h
+++ b/include/llvm/IR/BasicBlock.h
@@ -390,6 +390,11 @@ public:
   /// direct branches, switches, etc. to it.
   bool hasAddressTaken() const { return getSubclassDataFromValue() != 0; }
 
+  /// Returns true if there are any uses of the address of this basic block
+  /// that are call instructions (which may allow the address of this basic
+  /// block to escape).
+  bool addressPotentiallyEscapesFunction();
+
   /// Update all phi nodes in this basic block's successors to refer to basic
   /// block \p New instead of to it.
   void replaceSuccessorsPhiUsesWith(BasicBlock *New);

diff --git a/lib/Analysis/InlineCost.cpp b/lib/Analysis/InlineCost.cpp
index 574a1b6c8410a8d4ec29fd6edc877e374cea354a..2f5aa4a25766bd82e8208eefde85922780f2d5f8 100644 (file)
--- a/lib/Analysis/InlineCost.cpp
+++ b/lib/Analysis/InlineCost.cpp
@@ -1832,7 +1832,7 @@ InlineResult CallAnalyzer::analyzeCall(CallSite CS) {
     // see an indirect branch that ends up being dead code at a particular call
     // site. If the blockaddress escapes the function, e.g., via a global
     // variable, inlining may lead to an invalid cross-function reference.
-    if (BB->hasAddressTaken())
+    if (BB->hasAddressTaken() && BB->addressPotentiallyEscapesFunction())
       return "blockaddress";
 
     // Analyze the cost of this block. If we blow through the threshold, this
@@ -2082,7 +2082,7 @@ InlineResult llvm::isInlineViable(Function &F) {
     if (isa<IndirectBrInst>(BI->getTerminator()))
       return "contains indirect branches";
 
-    if (BI->hasAddressTaken())
+    if (BI->hasAddressTaken() && BI->addressPotentiallyEscapesFunction())
       return "uses block address";
 
     for (auto &II : *BI) {

diff --git a/lib/IR/BasicBlock.cpp b/lib/IR/BasicBlock.cpp
index 18e2fd898f72b3a7c75e8eb21eb83b70dc548993..7f2e762c29a60dcc627a97da9c4a3b729821f9b0 100644 (file)
--- a/lib/IR/BasicBlock.cpp
+++ b/lib/IR/BasicBlock.cpp
@@ -442,6 +442,14 @@ BasicBlock *BasicBlock::splitBasicBlock(iterator I, const Twine &BBName) {
   return New;
 }
 
+bool BasicBlock::addressPotentiallyEscapesFunction() {
+  for (const Use& U : BlockAddress::get(this)->uses())
+    if (const CallInst* CI = dyn_cast<CallInst>(U))
+      if (!CI->paramHasAttr(U.getOperandNo(), Attribute::NoCapture))
+        return true;
+  return false;
+}
+
 void BasicBlock::replaceSuccessorsPhiUsesWith(BasicBlock *New) {
   Instruction *TI = getTerminator();
   if (!TI)