[Inliner] Don't treat inalloca allocas as static

They aren't static, and moving them to the entry block across something
else will only result in tears.

Root cause of http://crbug.com/636558.

llvm-svn: 278571

1 files changed, 10 insertions, 3 deletions

diff --git a/llvm/lib/Transforms/Utils/InlineFunction.cpp b/llvm/lib/Transforms/Utils/InlineFunction.cpp
index e101412..6b2ff14f 100644
--- a/llvm/lib/Transforms/Utils/InlineFunction.cpp
+++ b/llvm/lib/Transforms/Utils/InlineFunction.cpp
@@ -1294,6 +1294,13 @@ updateInlinedAtInfo(const DebugLoc &DL, DILocation *InlinedAtNode,
   return DebugLoc::get(DL.getLine(), DL.getCol(), DL.getScope(), Last);
 }
 
+/// Return the result of AI->isStaticAlloca() if AI were moved to the entry
+/// block. Allocas used in inalloca calls and allocas of dynamic array size
+/// cannot be static.
+static bool allocaWouldBeStaticInEntry(const AllocaInst *AI ) {
+  return isa<Constant>(AI->getArraySize()) && !AI->isUsedWithInAlloca();
+}
+
 /// Update inlined instructions' line numbers to
 /// to encode location where these instructions are inlined.
 static void fixupLineNumbers(Function *Fn, Function::iterator FI,
@@ -1328,7 +1335,7 @@ static void fixupLineNumbers(Function *Fn, Function::iterator FI,
 
         // Don't update static allocas, as they may get moved later.
         if (auto *AI = dyn_cast<AllocaInst>(BI))
-          if (isa<Constant>(AI->getArraySize()))
+          if (allocaWouldBeStaticInEntry(AI))
             continue;
 
         BI->setDebugLoc(TheCallDL);
@@ -1626,7 +1633,7 @@ bool llvm::InlineFunction(CallSite CS, InlineFunctionInfo &IFI,
         continue;
       }
 
-      if (!isa<Constant>(AI->getArraySize()))
+      if (!allocaWouldBeStaticInEntry(AI))
         continue;
       
       // Keep track of the static allocas that we inline into the caller.
@@ -1635,7 +1642,7 @@ bool llvm::InlineFunction(CallSite CS, InlineFunctionInfo &IFI,
       // Scan for the block of allocas that we can move over, and move them
       // all at once.
       while (isa<AllocaInst>(I) &&
-             isa<Constant>(cast<AllocaInst>(I)->getArraySize())) {
+             allocaWouldBeStaticInEntry(cast<AllocaInst>(I))) {
         IFI.StaticAllocas.push_back(cast<AllocaInst>(I));
         ++I;
       }