Temporarily revert r104655 as it's breaking the bots.

llvm-svn: 104664

include/llvm/CodeGen/MachineFunction.h

@@ -114,13 +114,9 @@ class MachineFunction {
   ///
   unsigned FunctionNumber;
   
-  /// Alignment - The alignment of the function.
+  /// The alignment of the function.
   unsigned Alignment;
 
-  /// HasReturnsTwiceCall - Returns true if there's a call with a
-  /// "returns_twice" attribute, like setjmp.
-  bool HasReturnsTwiceCall;
-
   MachineFunction(const MachineFunction &); // DO NOT IMPLEMENT
   void operator=(const MachineFunction&);   // DO NOT IMPLEMENT
 public:
@@ -185,15 +181,6 @@ public:
   void EnsureAlignment(unsigned A) {
     if (Alignment < A) Alignment = A;
   }
-
-  /// hasReturnsTwiceCall - Returns true if there's a call with a
-  /// "returns_twice" attribute, like setjmp.
-  bool hasReturnsTwiceCall() const {
-    return HasReturnsTwiceCall;
-  }
-  void setReturnsTwiceCall(bool B) {
-    HasReturnsTwiceCall = B;
-  }
   
   /// getInfo - Keep track of various per-function pieces of information for
   /// backends that would like to do so.

lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp

@@ -25,7 +25,6 @@
 #include "llvm/Intrinsics.h"
 #include "llvm/IntrinsicInst.h"
 #include "llvm/LLVMContext.h"
-#include "llvm/Module.h"
 #include "llvm/CodeGen/FastISel.h"
 #include "llvm/CodeGen/GCStrategy.h"
 #include "llvm/CodeGen/GCMetadata.h"
@@ -254,39 +253,6 @@ bool SelectionDAGISel::runOnMachineFunction(MachineFunction &mf) {
   done:;
   }
 
-  // Set a flag indicating if the machine function makes a call to setjmp /
-  // sigsetjmp (i.e., a function marked "returns_twice"). We'll use this to
-  // disable certain optimizations which cannot handle such control flows.
-  // 
-  // FIXME: This goes beyond the setjmp/sigsetjmp functions. We should check for
-  // the GCC "returns twice" attribute.
-  const Module *M = Fn.getParent();
-  const Function *SetJmp = M->getFunction("setjmp");
-  const Function *SigSetJmp = M->getFunction("sigsetjmp");
-  bool HasReturnsTwiceCall = false;
-
-  if (SetJmp || SigSetJmp) {
-    if (SetJmp && !SetJmp->use_empty())
-      for (Value::const_use_iterator
-             I = SetJmp->use_begin(), E = SetJmp->use_end(); I != E; ++I)
-        if (const CallInst *CI = dyn_cast<CallInst>(I))
-          if (CI->getParent()->getParent() == &Fn) {
-            HasReturnsTwiceCall = true;
-            break;
-          }
-
-    if (!HasReturnsTwiceCall && SigSetJmp && !SigSetJmp->use_empty())
-      for (Value::const_use_iterator
-             I = SigSetJmp->use_begin(), E = SigSetJmp->use_end(); I != E; ++I)
-        if (const CallInst *CI = dyn_cast<CallInst>(I))
-          if (CI->getParent()->getParent() == &Fn) {
-            HasReturnsTwiceCall = true;
-            break;
-          }
-
-    mf.setReturnsTwiceCall(HasReturnsTwiceCall);
-  }
-
   // Release function-specific state. SDB and CurDAG are already cleared
   // at this point.
   FuncInfo->clear();

lib/CodeGen/StackSlotColoring.cpp

@@ -118,6 +118,7 @@ namespace {
 
   private:
     void InitializeSlots();
+    bool CheckForSetJmpCall(const MachineFunction &MF) const;
     void ScanForSpillSlotRefs(MachineFunction &MF);
     bool OverlapWithAssignments(LiveInterval *li, int Color) const;
     int ColorSlot(LiveInterval *li);
@@ -161,6 +162,34 @@ namespace {
   };
 }
 
+/// CheckForSetJmpCall - Return true if there's a call to setjmp/sigsetjmp in
+/// this function.
+bool StackSlotColoring::CheckForSetJmpCall(const MachineFunction &MF) const {
+  const Function *F = MF.getFunction();
+  const Module *M = F->getParent();
+  const Function *SetJmp = M->getFunction("setjmp");
+  const Function *SigSetJmp = M->getFunction("sigsetjmp");
+
+  if (!SetJmp && !SigSetJmp)
+    return false;
+
+  if (SetJmp && !SetJmp->use_empty())
+    for (Value::const_use_iterator
+           I = SetJmp->use_begin(), E = SetJmp->use_end(); I != E; ++I)
+      if (const CallInst *CI = dyn_cast<CallInst>(I))
+        if (CI->getParent()->getParent() == F)
+          return true;
+
+  if (SigSetJmp && !SigSetJmp->use_empty())
+    for (Value::const_use_iterator
+           I = SigSetJmp->use_begin(), E = SigSetJmp->use_end(); I != E; ++I)
+      if (const CallInst *CI = dyn_cast<CallInst>(I))
+        if (CI->getParent()->getParent() == F)
+          return true;
+
+  return false;
+}
+
 /// ScanForSpillSlotRefs - Scan all the machine instructions for spill slot
 /// references and update spill slot weights.
 void StackSlotColoring::ScanForSpillSlotRefs(MachineFunction &MF) {
@@ -724,11 +753,14 @@ bool StackSlotColoring::runOnMachineFunction(MachineFunction &MF) {
       return false;
   }
 
-  // If there is a call to a function with the attribute "returns_twice" (like
+  // If there are calls to setjmp or sigsetjmp, don't perform stack slot
-  // setjmp or sigsetjmp), don't perform stack slot coloring. The stack could be
+  // coloring. The stack could be modified before the longjmp is executed,
-  // modified before the the second return, resulting in the wrong value being
+  // resulting in the wrong value being used afterwards. (See
-  // used afterwards. (See <rdar://problem/8007500>.)
+  // <rdar://problem/8007500>.)
-  if (MF.hasReturnsTwiceCall())
+  //
+  // FIXME: This goes beyond the setjmp/sigsetjmp functions. Ideally, we should
+  // check for the GCC "returns twice" attribute.
+  if (CheckForSetJmpCall(MF))
     return false;
 
   // Gather spill slot references