[IR] Add verifier support for llvm.module.flags.

 - Also, update the LangRef documentation on module flags to match the
   implementation.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@172498 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 57 insertions, 0 deletions

diff --git a/lib/IR/Verifier.cpp b/lib/IR/Verifier.cpp
index 4252764..5a4a5a7 100644
--- a/lib/IR/Verifier.cpp
+++ b/lib/IR/Verifier.cpp
@@ -200,6 +200,8 @@ namespace {
            E = M.named_metadata_end(); I != E; ++I)
         visitNamedMDNode(*I);
 
+      visitModuleFlags(M);
+
       // If the module is broken, abort at this time.
       return abortIfBroken();
     }
@@ -240,6 +242,8 @@ namespace {
     void visitGlobalAlias(GlobalAlias &GA);
     void visitNamedMDNode(NamedMDNode &NMD);
     void visitMDNode(MDNode &MD, Function *F);
+    void visitModuleFlags(Module &M);
+    void visitModuleFlag(MDNode *Op, SmallSetVector<MDString*, 16> &SeenIDs);
     void visitFunction(Function &F);
     void visitBasicBlock(BasicBlock &BB);
     using InstVisitor<Verifier>::visit;
@@ -521,6 +525,59 @@ void Verifier::visitMDNode(MDNode &MD, Function *F) {
   }
 }
 
+void Verifier::visitModuleFlags(Module &M) {
+  const NamedMDNode *Flags = M.getModuleFlagsMetadata();
+  if (!Flags) return;
+
+  // Scan each flag.
+  SmallSetVector<MDString*, 16> SeenIDs;
+  for (unsigned I = 0, E = Flags->getNumOperands(); I != E; ++I) {
+    visitModuleFlag(Flags->getOperand(I), SeenIDs);
+  }
+}
+
+void Verifier::visitModuleFlag(MDNode *Op, 
+                               SmallSetVector<MDString*, 16> &SeenIDs) {
+  // Each module flag should have three arguments, the merge behavior (a
+  // constant int), the flag ID (an MDString), and the value.
+  Assert1(Op->getNumOperands() == 3,
+          "incorrect number of operands in module flag", Op);
+  ConstantInt *Behavior = dyn_cast<ConstantInt>(Op->getOperand(0));
+  MDString *ID = dyn_cast<MDString>(Op->getOperand(1));
+  Assert1(Behavior,
+          "invalid behavior operand in module flag (expected constant integer)",
+          Op->getOperand(0));
+  unsigned BehaviorValue = Behavior->getZExtValue();
+  Assert1((Module::Error <= BehaviorValue &&
+           BehaviorValue <= Module::Override),
+          "invalid behavior operand in module flag (unexpected constant)",
+          Op->getOperand(0));
+  Assert1(ID,
+          "invalid ID operand in module flag (expected metadata string)",
+          Op->getOperand(1));
+
+  // Unless this is a "requires" flag, check the ID is unique.
+  if (BehaviorValue != Module::Require) {
+    Assert1(SeenIDs.insert(ID),
+            "module flag identifiers must be unique (or of 'require' type)",
+            ID);
+  }
+
+  // If this is a "requires" flag, sanity check the value.
+  if (BehaviorValue == Module::Require) {
+    // The value should itself be an MDNode with two operands, a flag ID (an
+    // MDString), and a value.
+    MDNode *Value = dyn_cast<MDNode>(Op->getOperand(2));
+    Assert1(Value && Value->getNumOperands() == 2,
+            "invalid value for 'require' module flag (expected metadata pair)",
+            Op->getOperand(2));
+    Assert1(isa<MDString>(Value->getOperand(0)),
+            ("invalid value for 'require' module flag "
+             "(first value operand should be a string)"),
+            Value->getOperand(0));
+  }
+}
+
 // VerifyParameterAttrs - Check the given attributes for an argument or return
 // value of the specified type.  The value V is printed in error messages.
 void Verifier::VerifyParameterAttrs(Attribute Attrs, Type *Ty,