Move the check for "calls setjmp" to SelectionDAGISel so that it can be used by

more than just the stack slot coloring algorithm.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@104722 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/CodeGen/MachineFunction.h

@@ -114,9 +114,14 @@ class MachineFunction {
   ///
   unsigned FunctionNumber;
   
-  /// The alignment of the function.
+  /// Alignment - The alignment of the function.
   unsigned Alignment;
 
+  /// CallsSetJmp - True if the function calls setjmp or sigsetjmp. This is used
+  /// to limit optimizations which cannot reason about the control flow of
+  /// setjmp.
+  bool CallsSetJmp;
+
   MachineFunction(const MachineFunction &); // DO NOT IMPLEMENT
   void operator=(const MachineFunction&);   // DO NOT IMPLEMENT
 public:
@@ -181,6 +186,17 @@ public:
   void EnsureAlignment(unsigned A) {
     if (Alignment < A) Alignment = A;
   }
+
+  /// callsSetJmp - Returns true if the function calls setjmp or sigsetjmp.
+  bool callsSetJmp() const {
+    return CallsSetJmp;
+  }
+
+  /// setCallsSetJmp - Set a flag that indicates if there's a call to setjmp or
+  /// sigsetjmp.
+  void setCallsSetJmp(bool B) {
+    CallsSetJmp = B;
+  }
   
   /// getInfo - Keep track of various per-function pieces of information for
   /// backends that would like to do so.

lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp

@@ -25,6 +25,7 @@
 #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"
@@ -191,6 +192,34 @@ void SelectionDAGISel::getAnalysisUsage(AnalysisUsage &AU) const {
   MachineFunctionPass::getAnalysisUsage(AU);
 }
 
+/// FunctionCallsSetJmp - Return true if the function has a call to setjmp or
+/// sigsetjmp. This is used to limit code-gen optimizations on the machine
+/// function.
+static bool FunctionCallsSetJmp(const Function *F) {
+  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;
+}
+
 bool SelectionDAGISel::runOnMachineFunction(MachineFunction &mf) {
   // Do some sanity-checking on the command-line options.
   assert((!EnableFastISelVerbose || EnableFastISel) &&
@@ -253,6 +282,9 @@ bool SelectionDAGISel::runOnMachineFunction(MachineFunction &mf) {
   done:;
   }
 
+  // Determine if there is a call to setjmp in the machine function.
+  MF->setCallsSetJmp(FunctionCallsSetJmp(&Fn));
+
   // Release function-specific state. SDB and CurDAG are already cleared
   // at this point.
   FuncInfo->clear();

lib/CodeGen/StackSlotColoring.cpp

@@ -162,34 +162,6 @@ 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) {
@@ -757,10 +729,7 @@ bool StackSlotColoring::runOnMachineFunction(MachineFunction &MF) {
   // coloring. The stack could be modified before the longjmp is executed,
   // resulting in the wrong value being used afterwards. (See
   // <rdar://problem/8007500>.)
-  //
+  if (MF.callsSetJmp())
-  // 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