[IR] Add 'Append' and 'AppendUnique' module flag behaviors.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@172659 91177308-0d34-0410-b5e6-96231b3b80d8

docs/LangRef.rst

@@ -2508,6 +2508,16 @@ The following behaviors are supported:
            other module. If both modules specify **Override**, but the values
            differ, an error will be emitted.
 
+   * - 5
+     - **Append**
+           Appends the two values, which are required to be metadata nodes.
+
+   * - 6
+     - **AppendUnique**
+           Appends the two values, which are required to be metadata
+           nodes. However, duplicate entries in the second list are dropped
+           during the append operation.
+
 It is an error for a particular unique flag ID to have multiple behaviors,
 except in the case of **Require** (which adds restrictions on another metadata
 value) or **Override**.

include/llvm/IR/Module.h

@@ -147,30 +147,38 @@ public:
   /// An enumeration for describing the size of a pointer on the target machine.
   enum PointerSize { AnyPointerSize, Pointer32, Pointer64 };
 
-  /// An enumeration for the supported behaviors of module flags. The following
-  /// module flags behavior values are supported:
-  ///
-  ///    Value        Behavior
-  ///    -----        --------
-  ///      1          Error
-  ///                   Emits an error if two values disagree.
-  ///
-  ///      2          Warning
-  ///                   Emits a warning if two values disagree.
-  ///
-  ///      3          Require
-  ///                   Emits an error when the specified value is not present
-  ///                   or doesn't have the specified value. It is an error for
-  ///                   two (or more) llvm.module.flags with the same ID to have
-  ///                   the Require behavior but different values. There may be
-  ///                   multiple Require flags per ID.
-  ///
-  ///      4          Override
-  ///                   Uses the specified value if the two values disagree. It
-  ///                   is an error for two (or more) llvm.module.flags with the
-  ///                   same ID to have the Override behavior but different
-  ///                   values.
-  enum ModFlagBehavior { Error = 1, Warning  = 2, Require = 3, Override = 4 };
+  /// This enumeration defines the supported behaviors of module flags.
+  enum ModFlagBehavior {
+    /// Emits an error if two values disagree, otherwise the resulting value is
+    /// that of the operands.
+    Error = 1,
+
+    /// Emits a warning if two values disagree. The result value will be the
+    /// operand for the flag from the first module being linked.
+    Warning  = 2,
+
+    /// Adds a requirement that another module flag be present and have a
+    /// specified value after linking is performed. The value must be a metadata
+    /// pair, where the first element of the pair is the ID of the module flag
+    /// to be restricted, and the second element of the pair is the value the
+    /// module flag should be restricted to. This behavior can be used to
+    /// restrict the allowable results (via triggering of an error) of linking
+    /// IDs with the **Override** behavior.
+    Require = 3,
+
+    /// Uses the specified value, regardless of the behavior or value of the
+    /// other module. If both modules specify **Override**, but the values
+    /// differ, an error will be emitted.
+    Override = 4,
+
+    /// Appends the two values, which are required to be metadata nodes.
+    Append = 5,
+
+    /// Appends the two values, which are required to be metadata
+    /// nodes. However, duplicate entries in the second list are dropped
+    /// during the append operation.
+    AppendUnique = 6
+  };
 
   struct ModuleFlagEntry {
     ModFlagBehavior Behavior;

lib/IR/Verifier.cpp

@@ -571,24 +571,25 @@ void Verifier::visitModuleFlag(MDNode *Op, DenseMap<MDString*, MDNode*>&SeenIDs,
           "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) {
-    bool Inserted = SeenIDs.insert(std::make_pair(ID, Op)).second;
-    Assert1(Inserted,
-            "module flag identifiers must be unique (or of 'require' type)",
-            ID);
-  }
+  // Sanity check the values for behaviors with additional requirements.
+  switch (BehaviorValue) {
+  default:
+    Assert1(false,
+            "invalid behavior operand in module flag (unexpected constant)",
+            Op->getOperand(0));
+    break;
 
-  // If this is a "requires" flag, sanity check the value.
-  if (BehaviorValue == Module::Require) {
+  case Module::Error:
+  case Module::Warning:
+  case Module::Override:
+    // These behavior types accept any value.
+    break;
+
+  case 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));
@@ -603,6 +604,25 @@ void Verifier::visitModuleFlag(MDNode *Op, DenseMap<MDString*, MDNode*>&SeenIDs,
     // Append it to the list of requirements, to check once all module flags are
     // scanned.
     Requirements.push_back(Value);
+    break;
+  }
+
+  case Module::Append:
+  case Module::AppendUnique: {
+    // These behavior types require the operand be an MDNode.
+    Assert1(isa<MDNode>(Op->getOperand(2)),
+            "invalid value for 'append'-type module flag "
+            "(expected a metadata node)", Op->getOperand(2));
+    break;
+  }
+  }
+
+  // Unless this is a "requires" flag, check the ID is unique.
+  if (BehaviorValue != Module::Require) {
+    bool Inserted = SeenIDs.insert(std::make_pair(ID, Op)).second;
+    Assert1(Inserted,
+            "module flag identifiers must be unique (or of 'require' type)",
+            ID);
   }
 }
 

lib/Linker/LinkModules.cpp

@@ -1086,6 +1086,34 @@ bool ModuleLinker::linkModuleFlagsMetadata() {
       }
       continue;
     }
+    case Module::Append: {
+      MDNode *DstValue = cast<MDNode>(DstOp->getOperand(2));
+      MDNode *SrcValue = cast<MDNode>(SrcOp->getOperand(2));
+      unsigned NumOps = DstValue->getNumOperands() + SrcValue->getNumOperands();
+      Value **VP, **Values = VP = new Value*[NumOps];
+      for (unsigned i = 0, e = DstValue->getNumOperands(); i != e; ++i, ++VP)
+        *VP = DstValue->getOperand(i);
+      for (unsigned i = 0, e = SrcValue->getNumOperands(); i != e; ++i, ++VP)
+        *VP = SrcValue->getOperand(i);
+      DstOp->replaceOperandWith(2, MDNode::get(DstM->getContext(),
+                                               ArrayRef<Value*>(Values,
+                                                                NumOps)));
+      delete[] Values;
+      break;
+    }
+    case Module::AppendUnique: {
+      SmallSetVector<Value*, 16> Elts;
+      MDNode *DstValue = cast<MDNode>(DstOp->getOperand(2));
+      MDNode *SrcValue = cast<MDNode>(SrcOp->getOperand(2));
+      for (unsigned i = 0, e = DstValue->getNumOperands(); i != e; ++i)
+        Elts.insert(DstValue->getOperand(i));
+      for (unsigned i = 0, e = SrcValue->getNumOperands(); i != e; ++i)
+        Elts.insert(SrcValue->getOperand(i));
+      DstOp->replaceOperandWith(2, MDNode::get(DstM->getContext(),
+                                               ArrayRef<Value*>(Elts.begin(),
+                                                                Elts.end())));
+      break;
+    }
     }
   }
 

test/Linker/module-flags-8-a.ll

@@ -0,0 +1,14 @@
+; RUN: llvm-link %s %p/module-flags-8-b.ll -S -o - | sort | FileCheck %s
+
+; Test append-type module flags.
+
+; CHECK: !0 = metadata !{i32 5, metadata !"flag-0", metadata !1}
+; CHECK: !1 = metadata !{i32 0, i32 0, i32 1}
+; CHECK: !2 = metadata !{i32 6, metadata !"flag-1", metadata !3}
+; CHECK: !3 = metadata !{i32 0, i32 1, i32 2}
+; CHECK: !llvm.module.flags = !{!0, !2}
+
+!0 = metadata !{ i32 5, metadata !"flag-0", metadata !{ i32 0 } }
+!1 = metadata !{ i32 6, metadata !"flag-1", metadata !{ i32 0, i32 1 } }
+
+!llvm.module.flags = !{ !0, !1 }

test/Linker/module-flags-8-b.ll

@@ -0,0 +1,7 @@
+; This file is used with module-flags-6-a.ll
+; RUN: true
+
+!0 = metadata !{ i32 5, metadata !"flag-0", metadata !{ i32 0, i32 1 } }
+!1 = metadata !{ i32 6, metadata !"flag-1", metadata !{ i32 1, i32 2 } }
+
+!llvm.module.flags = !{ !0, !1 }

test/Verifier/module-flags-1.ll

@@ -33,6 +33,14 @@
 !9 = metadata !{ i32 2, metadata !"bar", i32 51 }
 !10 = metadata !{ i32 3, metadata !"bar", metadata !{ metadata !"bar", i32 51 } }
 
+; Check that any 'append'-type module flags are valid.
+; CHECK: invalid value for 'append'-type module flag (expected a metadata node)
+!16 = metadata !{ i32 5, metadata !"flag-2", i32 56 }
+; CHECK: invalid value for 'append'-type module flag (expected a metadata node)
+!17 = metadata !{ i32 5, metadata !"flag-3", i32 57 }
+; CHECK-NOT: invalid value for 'append'-type module flag (expected a metadata node)
+!18 = metadata !{ i32 5, metadata !"flag-4", metadata !{ i32 57 } }
+
 ; Check that any 'require' module flags are valid.
 ; CHECK: invalid requirement on flag, flag is not present in module
 !11 = metadata !{ i32 3, metadata !"bar",
@@ -48,4 +56,5 @@
      metadata !{ metadata !"flag-1", i32 55 } }
 
 !llvm.module.flags = !{
-  !0, !1, !2, !3, !4, !5, !6, !7, !8, !9, !10, !11, !12, !13, !14, !15 }
+  !0, !1, !2, !3, !4, !5, !6, !7, !8, !9, !10, !11, !12, !13, !14, !15,
+  !16, !17, !18 }