Beef up the interface to inline asm constraint parsing, making it more general, useful, and easier to use.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@25866 91177308-0d34-0410-b5e6-96231b3b80d8

lib/CodeGen/SelectionDAG/TargetLowering.cpp

@@ -243,15 +243,22 @@ bool TargetLowering::isMaskedValueZeroForTargetNode(const SDOperand &Op,
 
 std::vector<unsigned> TargetLowering::
 getRegForInlineAsmConstraint(const std::string &Constraint) const {
+  // Not a physreg, must not be a register reference or something.
+  if (Constraint[0] != '{') return std::vector<unsigned>();
+  assert(*(Constraint.end()-1) == '}' && "Not a brace enclosed constraint?");
+
+  // Remove the braces from around the name.
+  std::string RegName(Constraint.begin()+1, Constraint.end()-1);
+  
   // Scan to see if this constraint is a register name.
   const MRegisterInfo *RI = TM.getRegisterInfo();
   for (unsigned i = 1, e = RI->getNumRegs(); i != e; ++i) {
     if (const char *Name = RI->get(i).Name)
-      if (StringsEqualNoCase(Constraint, Name))
+      if (StringsEqualNoCase(RegName, Name))
         return std::vector<unsigned>(1, i);
   }
   
-  // Not a physreg, must not be a register reference or something.
+  // Unknown physreg.
   return std::vector<unsigned>();
 }
 

lib/VMCore/InlineAsm.cpp

@@ -38,50 +38,101 @@ const FunctionType *InlineAsm::getFunctionType() const {
   return cast<FunctionType>(getType()->getElementType());
 }
 
-std::vector<std::pair<InlineAsm::ConstraintPrefix, std::string> >
+/// Parse - Analyze the specified string (e.g. "==&{eax}") and fill in the
+/// fields in this structure.  If the constraint string is not understood,
+/// return true, otherwise return false.
+bool InlineAsm::ConstraintInfo::Parse(const std::string &Str) {
+  std::string::const_iterator I = Str.begin(), E = Str.end();
+  
+  // Initialize
+  Type = isInput;
+  isEarlyClobber = false;
+  isIndirectOutput =false;
+  
+  // Parse the prefix.
+  if (*I == '~') {
+    Type = isClobber;
+    ++I;
+  } else if (*I == '=') {
+    ++I;
+    Type = isOutput;
+    if (I != E && *I == '=') {
+      isIndirectOutput = true;
+      ++I;
+    }
+  }
+  
+  if (I == E) return true;  // Just a prefix, like "==" or "~".
+  
+  // Parse the modifiers.
+  bool DoneWithModifiers = false;
+  while (!DoneWithModifiers) {
+    switch (*I) {
+    default:
+      DoneWithModifiers = true;
+      break;
+    case '&':
+      if (Type != isOutput ||      // Cannot early clobber anything but output.
+          isEarlyClobber)          // Reject &&&&&&
+        return true;
+      isEarlyClobber = true;
+      break;
+    }
+    
+    if (!DoneWithModifiers) {
+      ++I;
+      if (I == E) return true;   // Just prefixes and modifiers!
+    }
+  }
+  
+  // Parse the various constraints.
+  while (I != E) {
+    if (*I == '{') {   // Physical register reference.
+      // Find the end of the register name.
+      std::string::const_iterator ConstraintEnd = std::find(I+1, E, '}');
+      if (ConstraintEnd == E) return true;  // "{foo"
+      Codes.push_back(std::string(I, ConstraintEnd+1));
+      I = ConstraintEnd+1;
+    } else if (isdigit(*I)) {
+      // Maximal munch numbers.
+      std::string::const_iterator NumStart = I;
+      while (I != E && isdigit(*I))
+        ++I;
+      Codes.push_back(std::string(NumStart, I));
+    } else {
+      // Single letter constraint.
+      Codes.push_back(std::string(I, I+1));
+      ++I;
+    }
+  }
+
+  return false;
+}
+
+std::vector<InlineAsm::ConstraintInfo>
 InlineAsm::ParseConstraints(const std::string &Constraints) {
-  std::vector<std::pair<InlineAsm::ConstraintPrefix, std::string> > Result;
+  std::vector<ConstraintInfo> Result;
   
   // Scan the constraints string.
   for (std::string::const_iterator I = Constraints.begin(), 
        E = Constraints.end(); I != E; ) {
-    if (*I == ',') { Result.clear(); break; } // Empty constraint like ",,"
+    ConstraintInfo Info;
 
-    // Parse the prefix.
+    // Find the end of this constraint.
-    ConstraintPrefix ConstraintType = isInput;
+    std::string::const_iterator ConstraintEnd = std::find(I, E, ',');
 
-    if (*I == '~') {
+    if (ConstraintEnd == I ||  // Empty constraint like ",,"
-      ConstraintType = isClobber;
+        Info.Parse(std::string(I, ConstraintEnd))) {   // Erroneous constraint?
-      ++I;
-    } else if (*I == '=') {
-      ++I;
-      if (I != E && *I == '=') {
-        ConstraintType = isIndirectOutput;
-        ++I;
-      } else {
-        ConstraintType = isOutput;
-      }
-    }
-    
-    if (I == E) { Result.clear(); break; }  // Just a prefix, like "==" or "~".
-    
-    std::string::const_iterator IdStart = I;
-      
-    // Parse the id.  We accept [a-zA-Z0-9] currently.
-    while (I != E && isalnum(*I)) ++I;
-    
-    if (IdStart == I) {                    // Requires more than just a prefix
       Result.clear();
       break;
     }
 
-    // Remember this constraint.
+    Result.push_back(Info);
-    Result.push_back(std::make_pair(ConstraintType, std::string(IdStart, I)));
     
-    // If we reached the end of the ID, we must have the end of the string or a
+    // ConstraintEnd may be either the next comma or the end of the string.  In
-    // comma, which we skip now.
+    // the former case, we skip the comma.
+    I = ConstraintEnd;
     if (I != E) {
-      if (*I != ',') { Result.clear(); break; }
       ++I;
       if (I == E) { Result.clear(); break; }    // don't allow "xyz,"
     }
@@ -96,8 +147,7 @@ InlineAsm::ParseConstraints(const std::string &Constraints) {
 bool InlineAsm::Verify(const FunctionType *Ty, const std::string &ConstStr) {
   if (Ty->isVarArg()) return false;
   
-  std::vector<std::pair<ConstraintPrefix, std::string> >
+  std::vector<ConstraintInfo> Constraints = ParseConstraints(ConstStr);
-  Constraints = ParseConstraints(ConstStr);
   
   // Error parsing constraints.
   if (Constraints.empty() && !ConstStr.empty()) return false;
@@ -105,17 +155,19 @@ bool InlineAsm::Verify(const FunctionType *Ty, const std::string &ConstStr) {
   unsigned NumOutputs = 0, NumInputs = 0, NumClobbers = 0;
   
   for (unsigned i = 0, e = Constraints.size(); i != e; ++i) {
-    switch (Constraints[i].first) {
+    switch (Constraints[i].Type) {
-    case isOutput:
+    case InlineAsm::isOutput:
+      if (!Constraints[i].isIndirectOutput) {
         if (NumInputs || NumClobbers) return false;  // outputs come first.
         ++NumOutputs;
         break;
-    case isInput:
+      }
-    case isIndirectOutput:
+      // FALLTHROUGH for IndirectOutputs.
+    case InlineAsm::isInput:
       if (NumClobbers) return false;               // inputs before clobbers.
       ++NumInputs;
       break;
-    case isClobber:
+    case InlineAsm::isClobber:
       ++NumClobbers;
       break;
     }