Keep track of *which* input constraint matches an output

constraint.  Reject asms where an output has multiple
input constraints tied to it.

llvm-svn: 57687

1 files changed, 7 insertions, 2 deletions

diff --git a/llvm/lib/VMCore/InlineAsm.cpp b/llvm/lib/VMCore/InlineAsm.cpp
index 5eefc8842ba..524e294ab75 100644
--- a/llvm/lib/VMCore/InlineAsm.cpp
+++ b/llvm/lib/VMCore/InlineAsm.cpp
@@ -57,7 +57,7 @@ bool InlineAsm::ConstraintInfo::Parse(const std::string &Str,
   // Initialize
   Type = isInput;
   isEarlyClobber = false;
-  hasMatchingInput = false;
+  MatchingInput = -1;
   isCommutative = false;
   isIndirect = false;
   
@@ -127,8 +127,13 @@ bool InlineAsm::ConstraintInfo::Parse(const std::string &Str,
           Type != isInput)
         return true;  // Invalid constraint number.
       
+      // If Operand N already has a matching input, reject this.  An output
+      // can't be constrained to the same value as multiple inputs.
+      if (ConstraintsSoFar[N].hasMatchingInput())
+        return true;
+      
       // Note that operand #n has a matching input.
-      ConstraintsSoFar[N].hasMatchingInput = true;
+      ConstraintsSoFar[N].MatchingInput = ConstraintsSoFar.size();
     } else {
       // Single letter constraint.
       Codes.push_back(std::string(I, I+1));