[X86][Haswell][SchedModel] Add architecture specific scheduling models.

[oota-llvm.git] / lib / Analysis / IPA / InlineCost.cpp

diff --git a/lib/Analysis/IPA/InlineCost.cpp b/lib/Analysis/IPA/InlineCost.cpp
index c43b5ca250698b45d32a33046f98496c57ec7d45..8807529cabac1ba44607fd5645e81eb1eb0e1425 100644 (file)
--- a/lib/Analysis/IPA/InlineCost.cpp
+++ b/lib/Analysis/IPA/InlineCost.cpp
@@ -808,9 +808,29 @@ bool CallAnalyzer::visitBranchInst(BranchInst &BI) {
 bool CallAnalyzer::visitSwitchInst(SwitchInst &SI) {
   // We model unconditional switches as free, see the comments on handling
   // branches.
-  return isa<ConstantInt>(SI.getCondition()) ||
-         dyn_cast_or_null<ConstantInt>(
-             SimplifiedValues.lookup(SI.getCondition()));
+  if (isa<ConstantInt>(SI.getCondition()))
+    return true;
+  if (Value *V = SimplifiedValues.lookup(SI.getCondition()))
+    if (isa<ConstantInt>(V))
+      return true;
+
+  // Otherwise, we need to accumulate a cost proportional to the number of
+  // distinct successor blocks. This fan-out in the CFG cannot be represented
+  // for free even if we can represent the core switch as a jumptable that
+  // takes a single instruction.
+  //
+  // NB: We convert large switches which are just used to initialize large phi
+  // nodes to lookup tables instead in simplify-cfg, so this shouldn't prevent
+  // inlining those. It will prevent inlining in cases where the optimization
+  // does not (yet) fire.
+  SmallPtrSet<BasicBlock *, 8> SuccessorBlocks;
+  SuccessorBlocks.insert(SI.getDefaultDest());
+  for (auto I = SI.case_begin(), E = SI.case_end(); I != E; ++I)
+    SuccessorBlocks.insert(I.getCaseSuccessor());
+  // Add cost corresponding to the number of distinct destinations. The first
+  // we model as free because of fallthrough.
+  Cost += (SuccessorBlocks.size() - 1) * InlineConstants::InstrCost;
+  return false;
 }
 
 bool CallAnalyzer::visitIndirectBrInst(IndirectBrInst &IBI) {
@@ -821,10 +841,7 @@ bool CallAnalyzer::visitIndirectBrInst(IndirectBrInst &IBI) {
   // original function which is extremely undefined behavior.
   // FIXME: This logic isn't really right; we can safely inline functions with
   // indirectbr's as long as no other function or global references the
-  // blockaddress of a block within the current function.  And as a QOI issue,
-  // if someone is using a blockaddress without an indirectbr, and that
-  // reference somehow ends up in another function or global, we probably don't
-  // want to inline this function.
+  // blockaddress of a block within the current function.
   HasIndirectBr = true;
   return false;
 }
@@ -1101,6 +1118,15 @@ bool CallAnalyzer::analyzeCall(CallSite CS) {
     if (BB->empty())
       continue;
 
+    // Disallow inlining a blockaddress. A blockaddress only has defined
+    // behavior for an indirect branch in the same function, and we do not
+    // currently support inlining indirect branches. But, the inliner may not
+    // 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())
+      return false;
+
     // Analyze the cost of this block. If we blow through the threshold, this
     // returns false, and we can bail on out.
     if (!analyzeBlock(BB)) {
@@ -1239,7 +1265,7 @@ InlineCost InlineCostAnalysis::getInlineCost(CallSite CS, Function *Callee,
 
   // Calls to functions with always-inline attributes should be inlined
   // whenever possible.
-  if (Callee->hasFnAttribute(Attribute::AlwaysInline)) {
+  if (CS.hasFnAttr(Attribute::AlwaysInline)) {
     if (isInlineViable(*Callee))
       return llvm::InlineCost::getAlways();
     return llvm::InlineCost::getNever();
@@ -1283,8 +1309,9 @@ bool InlineCostAnalysis::isInlineViable(Function &F) {
     F.getAttributes().hasAttribute(AttributeSet::FunctionIndex,
                                    Attribute::ReturnsTwice);
   for (Function::iterator BI = F.begin(), BE = F.end(); BI != BE; ++BI) {
-    // Disallow inlining of functions which contain an indirect branch.
-    if (isa<IndirectBrInst>(BI->getTerminator()))
+    // Disallow inlining of functions which contain indirect branches or
+    // blockaddresses.
+    if (isa<IndirectBrInst>(BI->getTerminator()) || BI->hasAddressTaken())
       return false;
 
     for (BasicBlock::iterator II = BI->begin(), IE = BI->end(); II != IE;