1 files changed, 14 insertions, 9 deletions

diff --git a/llvm/lib/Analysis/InlineCost.cpp b/llvm/lib/Analysis/InlineCost.cpp
index 48666566dd9..c66b9f38942 100644
--- a/llvm/lib/Analysis/InlineCost.cpp
+++ b/llvm/lib/Analysis/InlineCost.cpp
@@ -2022,9 +2022,10 @@ InlineCost llvm::getInlineCost(
   // Calls to functions with always-inline attributes should be inlined
   // whenever possible.
   if (CS.hasFnAttr(Attribute::AlwaysInline)) {
-    if (isInlineViable(*Callee))
+    auto IsViable = isInlineViable(*Callee);
+    if (IsViable)
       return llvm::InlineCost::getAlways("always inline attribute");
-    return llvm::InlineCost::getNever("inapplicable always inline attribute");
+    return llvm::InlineCost::getNever(IsViable.message);
   }
 
   // Never inline functions with conflicting attributes (unless callee has
@@ -2072,14 +2073,16 @@ InlineCost llvm::getInlineCost(
   return llvm::InlineCost::get(CA.getCost(), CA.getThreshold());
 }
 
-bool llvm::isInlineViable(Function &F) {
+InlineResult llvm::isInlineViable(Function &F) {
   bool ReturnsTwice = F.hasFnAttribute(Attribute::ReturnsTwice);
   for (Function::iterator BI = F.begin(), BE = F.end(); BI != BE; ++BI) {
     // Disallow inlining of functions which contain indirect branches or
     // blockaddresses.
-    if (isa<IndirectBrInst>(BI->getTerminator()) ||
-        BI->hasAddressTaken())
-      return false;
+    if (isa<IndirectBrInst>(BI->getTerminator()))
+      return "contains indirect branches";
+
+    if (BI->hasAddressTaken())
+      return "uses block address";
 
     for (auto &II : *BI) {
       CallSite CS(&II);
@@ -2088,13 +2091,13 @@ bool llvm::isInlineViable(Function &F) {
 
       // Disallow recursive calls.
       if (&F == CS.getCalledFunction())
-        return false;
+        return "recursive call";
 
       // Disallow calls which expose returns-twice to a function not previously
       // attributed as such.
       if (!ReturnsTwice && CS.isCall() &&
           cast<CallInst>(CS.getInstruction())->canReturnTwice())
-        return false;
+        return "exposes returns-twice attribute";
 
       if (CS.getCalledFunction())
         switch (CS.getCalledFunction()->getIntrinsicID()) {
@@ -2103,12 +2106,14 @@ bool llvm::isInlineViable(Function &F) {
         // Disallow inlining of @llvm.icall.branch.funnel because current
         // backend can't separate call targets from call arguments.
         case llvm::Intrinsic::icall_branch_funnel:
+          return "disallowed inlining of @llvm.icall.branch.funnel";
         // Disallow inlining functions that call @llvm.localescape. Doing this
         // correctly would require major changes to the inliner.
         case llvm::Intrinsic::localescape:
+          return "disallowed inlining of @llvm.localescape";
         // Disallow inlining of functions that initialize VarArgs with va_start.
         case llvm::Intrinsic::vastart:
-          return false;
+          return "contains VarArgs initialized with va_start";
         }
     }
   }