Add some support for diagnosing possibly mismatched constraint, type size and

modifiers. (From an idea by Eric...)
<rdar://problem/12284092>

llvm-svn: 166647

2 files changed, 71 insertions, 0 deletions

diff --git a/clang/lib/Basic/Targets.cpp b/clang/lib/Basic/Targets.cpp
index ba96185f72d..960a2858e41 100644
--- a/clang/lib/Basic/Targets.cpp
+++ b/clang/lib/Basic/Targets.cpp
@@ -3315,6 +3315,29 @@ public:
     }
     return R;
   }
+  virtual bool validateConstraintModifier(StringRef Constraint,
+                                          const char Modifier,
+                                          unsigned Size) const {
+    // Strip off constraint modifiers.
+    while (Constraint[0] == '=' ||
+           Constraint[0] == '+' ||
+           Constraint[0] == '&')
+      Constraint = Constraint.substr(1);
+
+    switch (Constraint[0]) {
+    default: break;
+    case 'r': {
+      switch (Modifier) {
+      default: return Size == 32;
+      case 'q':
+        // A register of size 32 cannot fit a vector type.
+        return false;
+      }
+    }
+    }
+
+    return true;
+  }
   virtual const char *getClobbers() const {
     // FIXME: Is this really right?
     return "";
diff --git a/clang/lib/Sema/SemaStmtAsm.cpp b/clang/lib/Sema/SemaStmtAsm.cpp
index 3a5f40c74fa..138d6714701 100644
--- a/clang/lib/Sema/SemaStmtAsm.cpp
+++ b/clang/lib/Sema/SemaStmtAsm.cpp
@@ -208,6 +208,54 @@ StmtResult Sema::ActOnGCCAsmStmt(SourceLocation AsmLoc, bool IsSimple,
     return StmtError();
   }
 
+  // Validate constraints and modifiers.
+  for (unsigned i = 0, e = Pieces.size(); i != e; ++i) {
+    GCCAsmStmt::AsmStringPiece &Piece = Pieces[i];
+    if (!Piece.isOperand()) continue;
+
+    // Look for the correct constraint index.
+    unsigned Idx = 0;
+    unsigned ConstraintIdx = 0;
+    for (unsigned i = 0, e = NS->getNumOutputs(); i != e; ++i, ++ConstraintIdx) {
+      TargetInfo::ConstraintInfo &Info = OutputConstraintInfos[i];
+      if (Idx == Piece.getOperandNo())
+        break;
+      ++Idx;
+
+      if (Info.isReadWrite()) {
+        if (Idx == Piece.getOperandNo())
+          break;
+        ++Idx;
+      }
+    }
+
+    for (unsigned i = 0, e = NS->getNumInputs(); i != e; ++i, ++ConstraintIdx) {
+      TargetInfo::ConstraintInfo &Info = InputConstraintInfos[i];
+      if (Idx == Piece.getOperandNo())
+        break;
+      ++Idx;
+
+      if (Info.isReadWrite()) {
+        if (Idx == Piece.getOperandNo())
+          break;
+        ++Idx;
+      }
+    }
+    
+    // Now that we have the right indexes go ahead and check.
+    StringLiteral *Literal = Constraints[ConstraintIdx];
+    const Type *Ty = Exprs[ConstraintIdx]->getType().getTypePtr();
+    if (Ty->isDependentType() || Ty->isIncompleteType())
+      continue;
+
+    unsigned Size = Context.getTypeSize(Ty);
+    if (!Context.getTargetInfo()
+        .validateConstraintModifier(Literal->getString(),
+                                    Piece.getModifier(), Size))
+      Diag(Exprs[ConstraintIdx]->getLocStart(),
+           diag::warn_mismatched_size_modifier);
+  }
+
   // Validate tied input operands for type mismatches.
   for (unsigned i = 0, e = InputConstraintInfos.size(); i != e; ++i) {
     TargetInfo::ConstraintInfo &Info = InputConstraintInfos[i];