Use the function attributes to pass along the stack protector buffer size.

Now that we have robust function attributes, don't use a command line option to
specify the stack protecto buffer size.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@186217 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/CodeGen/CommandFlags.h

@@ -220,8 +220,4 @@ cl::opt<std::string> StartAfter("start-after",
                           cl::value_desc("pass-name"),
                           cl::init(""));
 
-cl::opt<unsigned>
-SSPBufferSize("stack-protector-buffer-size", cl::init(8),
-              cl::desc("Lower bound for a buffer to be considered for "
-                       "stack protection"));
 #endif

include/llvm/Target/TargetOptions.h

@@ -48,7 +48,7 @@ namespace llvm {
           UseSoftFloat(false), NoZerosInBSS(false),
           JITEmitDebugInfo(false), JITEmitDebugInfoToDisk(false),
           GuaranteedTailCallOpt(false), DisableTailCalls(false),
-          StackAlignmentOverride(0), RealignStack(true), SSPBufferSize(0),
+          StackAlignmentOverride(0), RealignStack(true),
           EnableFastISel(false), PositionIndependentExecutable(false),
           EnableSegmentedStacks(false), UseInitArray(false), TrapFuncName(""),
           FloatABIType(FloatABI::Default), AllowFPOpFusion(FPOpFusion::Standard)
@@ -151,10 +151,6 @@ namespace llvm {
     /// automatically realigned, if needed.
     unsigned RealignStack : 1;
 
-    /// SSPBufferSize - The minimum size of buffers that will receive stack
-    /// smashing protection when -fstack-protection is used.
-    unsigned SSPBufferSize;
-
     /// EnableFastISel - This flag enables fast-path instruction selection
     /// which trades away generated code quality in favor of reducing
     /// compile time.
@@ -224,7 +220,6 @@ inline bool operator==(const TargetOptions &LHS,
     ARE_EQUAL(DisableTailCalls) &&
     ARE_EQUAL(StackAlignmentOverride) &&
     ARE_EQUAL(RealignStack) &&
-    ARE_EQUAL(SSPBufferSize) &&
     ARE_EQUAL(EnableFastISel) &&
     ARE_EQUAL(PositionIndependentExecutable) &&
     ARE_EQUAL(EnableSegmentedStacks) &&

lib/CodeGen/StackProtector.cpp

@@ -33,6 +33,7 @@
 #include "llvm/Pass.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Target/TargetLowering.h"
+#include <cstdlib>
 using namespace llvm;
 
 STATISTIC(NumFunProtected, "Number of functions protected");
@@ -53,6 +54,10 @@ namespace {
 
     DominatorTree *DT;
 
+    /// \brief The minimum size of buffers that will receive stack smashing
+    /// protection when -fstack-protection is used.
+    unsigned SSPBufferSize;
+
     /// VisitedPHIs - The set of PHI nodes visited when determining
     /// if a variable's reference has been taken.  This set 
     /// is maintained to ensure we don't visit the same PHI node multiple
@@ -85,11 +90,12 @@ namespace {
     bool RequiresStackProtector();
   public:
     static char ID;             // Pass identification, replacement for typeid.
-    StackProtector() : FunctionPass(ID), TM(0), TLI(0) {
+    StackProtector() : FunctionPass(ID), TM(0), TLI(0), SSPBufferSize(0) {
       initializeStackProtectorPass(*PassRegistry::getPassRegistry());
     }
     StackProtector(const TargetMachine *TM)
-      : FunctionPass(ID), TM(TM), TLI(0), Trip(TM->getTargetTriple()) {
+      : FunctionPass(ID), TM(TM), TLI(0), Trip(TM->getTargetTriple()),
+        SSPBufferSize(8) {
       initializeStackProtectorPass(*PassRegistry::getPassRegistry());
     }
 
@@ -117,6 +123,12 @@ bool StackProtector::runOnFunction(Function &Fn) {
 
   if (!RequiresStackProtector()) return false;
 
+  Attribute Attr =
+    Fn.getAttributes().getAttribute(AttributeSet::FunctionIndex,
+                                    "ssp-buffer-size");
+  if (Attr.isStringAttribute())
+    SSPBufferSize = atoi(Attr.getValueAsString().data());
+
   ++NumFunProtected;
   return InsertStackProtectors();
 }
@@ -132,7 +144,6 @@ bool StackProtector::ContainsProtectableArray(Type *Ty, bool Strong,
     // protector
     if (Strong)
       return true;
-    const TargetMachine &TM = TLI->getTargetMachine();
     if (!AT->getElementType()->isIntegerTy(8)) {
       // If we're on a non-Darwin platform or we're inside of a structure, don't
       // add stack protectors unless the array is a character array.
@@ -142,7 +153,7 @@ bool StackProtector::ContainsProtectableArray(Type *Ty, bool Strong,
 
     // If an array has more than SSPBufferSize bytes of allocated space, then we
     // emit stack protectors.
-    if (TM.Options.SSPBufferSize <= TLI->getDataLayout()->getTypeAllocSize(AT))
+    if (SSPBufferSize <= TLI->getDataLayout()->getTypeAllocSize(AT))
       return true;
   }
 
@@ -230,13 +241,14 @@ bool StackProtector::RequiresStackProtector() {
   
           if (const ConstantInt *CI =
                dyn_cast<ConstantInt>(AI->getArraySize())) {
-            unsigned BufferSize = TLI->getTargetMachine().Options.SSPBufferSize;
-            if (CI->getLimitedValue(BufferSize) >= BufferSize)
+            if (CI->getLimitedValue(SSPBufferSize) >= SSPBufferSize)
               // A call to alloca with size >= SSPBufferSize requires
               // stack protectors.
               return true;
-          } else // A call to alloca with a variable size requires protectors.
+          } else {
+            // A call to alloca with a variable size requires protectors.
             return true;
+          }
         }
 
         if (ContainsProtectableArray(AI->getAllocatedType(), Strong))

tools/llc/llc.cpp

@@ -280,7 +280,6 @@ static int compileModule(char **argv, LLVMContext &Context) {
   Options.PositionIndependentExecutable = EnablePIE;
   Options.EnableSegmentedStacks = SegmentedStacks;
   Options.UseInitArray = UseInitArray;
-  Options.SSPBufferSize = SSPBufferSize;
 
   OwningPtr<TargetMachine>
     target(TheTarget->createTargetMachine(TheTriple.getTriple(),

tools/lto/LTOModule.cpp

@@ -151,11 +151,6 @@ UseInitArray("use-init-array",
   cl::desc("Use .init_array instead of .ctors."),
   cl::init(false));
 
-static cl::opt<unsigned>
-SSPBufferSize("stack-protector-buffer-size", cl::init(8),
-              cl::desc("Lower bound for a buffer to be considered for "
-                       "stack protection"));
-
 LTOModule::LTOModule(llvm::Module *m, llvm::TargetMachine *t)
   : _module(m), _target(t),
     _context(_target->getMCAsmInfo(), _target->getRegisterInfo(), NULL),
@@ -261,7 +256,6 @@ void LTOModule::getTargetOptions(TargetOptions &Options) {
   Options.PositionIndependentExecutable = EnablePIE;
   Options.EnableSegmentedStacks = SegmentedStacks;
   Options.UseInitArray = UseInitArray;
-  Options.SSPBufferSize = SSPBufferSize;
 }
 
 LTOModule *LTOModule::makeLTOModule(MemoryBuffer *buffer,

tools/opt/opt.cpp

@@ -510,7 +510,6 @@ static TargetOptions GetTargetOptions() {
   Options.PositionIndependentExecutable = EnablePIE;
   Options.EnableSegmentedStacks = SegmentedStacks;
   Options.UseInitArray = UseInitArray;
-  Options.SSPBufferSize = SSPBufferSize;
   return Options;
 }