Make it possible to indicate relaxed floating point requirements at the IR level

through the use of 'fpmath' metadata.  Currently this only provides a 'fpaccuracy'
value, which may be a number in ULPs or the keyword 'fast', however the intent is
that this will be extended with additional information about NaN's, infinities
etc later.  No optimizations have been hooked up to this so far.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@154822 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 44 insertions, 18 deletions

diff --git a/include/llvm/Support/MDBuilder.h b/include/llvm/Support/MDBuilder.h
index 022e8e375c..f6d84526ab 100644
--- a/include/llvm/Support/MDBuilder.h
+++ b/include/llvm/Support/MDBuilder.h
@@ -26,20 +26,46 @@ namespace llvm {
   class MDBuilder {
     LLVMContext &Context;
 
+    MDString *getFastString() {
+      return createString("fast");
+    }
   public:
     MDBuilder(LLVMContext &context) : Context(context) {}
 
-    /// CreateString - Return the given string as metadata.
-    MDString *CreateString(StringRef Str) {
+    /// \brief Return the given string as metadata.
+    MDString *createString(StringRef Str) {
       return MDString::get(Context, Str);
     }
 
     //===------------------------------------------------------------------===//
+    // FPMath metadata.
+    //===------------------------------------------------------------------===//
+
+    /// \brief Return metadata with appropriate settings for 'fast math'.
+    MDNode *createFastFPMath() {
+      return MDNode::get(Context, getFastString());
+    }
+
+    /// \brief Return metadata with the given settings.  Special values for the
+    /// Accuracy parameter are 0.0, which means the default (maximal precision)
+    /// setting; and negative values which all mean 'fast'.
+    MDNode *createFPMath(float Accuracy) {
+      if (Accuracy == 0.0)
+        return 0;
+      if (Accuracy < 0.0)
+        return MDNode::get(Context, getFastString());
+      assert(Accuracy > 0.0 && "Invalid fpmath accuracy!");
+      Value *Op = ConstantFP::get(Type::getFloatTy(Context), Accuracy);
+      return MDNode::get(Context, Op);
+    }
+
+
+    //===------------------------------------------------------------------===//
     // Range metadata.
     //===------------------------------------------------------------------===//
 
-    /// CreateRange - Return metadata describing the range [Lo, Hi).
-    MDNode *CreateRange(const APInt &Lo, const APInt &Hi) {
+    /// \brief Return metadata describing the range [Lo, Hi).
+    MDNode *createRange(const APInt &Lo, const APInt &Hi) {
       assert(Lo.getBitWidth() == Hi.getBitWidth() && "Mismatched bitwidths!");
       // If the range is everything then it is useless.
       if (Hi == Lo)
@@ -56,10 +82,10 @@ namespace llvm {
     // TBAA metadata.
     //===------------------------------------------------------------------===//
 
-    /// CreateAnonymousTBAARoot - Return metadata appropriate for a TBAA root
-    /// node.  Each returned node is distinct from all other metadata and will
-    /// never be identified (uniqued) with anything else.
-    MDNode *CreateAnonymousTBAARoot() {
+    /// \brief Return metadata appropriate for a TBAA root node.  Each returned
+    /// node is distinct from all other metadata and will never be identified
+    /// (uniqued) with anything else.
+    MDNode *createAnonymousTBAARoot() {
       // To ensure uniqueness the root node is self-referential.
       MDNode *Dummy = MDNode::getTemporary(Context, ArrayRef<Value*>());
       MDNode *Root = MDNode::get(Context, Dummy);
@@ -74,23 +100,23 @@ namespace llvm {
       return Root;
     }
 
-    /// CreateTBAARoot - Return metadata appropriate for a TBAA root node with
-    /// the given name.  This may be identified (uniqued) with other roots with
-    /// the same name.
-    MDNode *CreateTBAARoot(StringRef Name) {
-      return MDNode::get(Context, CreateString(Name));
+    /// \brief Return metadata appropriate for a TBAA root node with the given
+    /// name.  This may be identified (uniqued) with other roots with the same
+    /// name.
+    MDNode *createTBAARoot(StringRef Name) {
+      return MDNode::get(Context, createString(Name));
     }
 
-    /// CreateTBAANode - Return metadata for a non-root TBAA node with the given
-    /// name, parent in the TBAA tree, and value for 'pointsToConstantMemory'.
-    MDNode *CreateTBAANode(StringRef Name, MDNode *Parent,
+    /// \brief Return metadata for a non-root TBAA node with the given name,
+    /// parent in the TBAA tree, and value for 'pointsToConstantMemory'.
+    MDNode *createTBAANode(StringRef Name, MDNode *Parent,
                            bool isConstant = false) {
       if (isConstant) {
         Constant *Flags = ConstantInt::get(Type::getInt64Ty(Context), 1);
-        Value *Ops[3] = { CreateString(Name), Parent, Flags };
+        Value *Ops[3] = { createString(Name), Parent, Flags };
         return MDNode::get(Context, Ops);
       } else {
-        Value *Ops[2] = { CreateString(Name), Parent };
+        Value *Ops[2] = { createString(Name), Parent };
         return MDNode::get(Context, Ops);
       }
     }