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, 10 insertions, 6 deletions

diff --git a/lib/VMCore/Verifier.cpp b/lib/VMCore/Verifier.cpp
index ab79d8ce62..2576766928 100644
--- a/lib/VMCore/Verifier.cpp
+++ b/lib/VMCore/Verifier.cpp
@@ -1657,12 +1657,16 @@ void Verifier::visitInstruction(Instruction &I) {
     Assert1(I.getType()->isFPOrFPVectorTy(),
             "fpmath requires a floating point result!", &I);
     Assert1(MD->getNumOperands() == 1, "fpmath takes one operand!", &I);
-    ConstantFP *Op = dyn_cast_or_null<ConstantFP>(MD->getOperand(0));
-    Assert1(Op, "fpmath ULPs not a floating point number!", &I);
-    APFloat ULPs = Op->getValueAPF();
-    Assert1(ULPs.isNormal() || ULPs.isZero(),
-            "fpmath ULPs not a normal number!", &I);
-    Assert1(!ULPs.isNegative(), "fpmath ULPs is negative!", &I);
+    Value *Op0 = MD->getOperand(0);
+    if (ConstantFP *CFP0 = dyn_cast_or_null<ConstantFP>(Op0)) {
+      APFloat Accuracy = CFP0->getValueAPF();
+      Assert1(Accuracy.isNormal() && !Accuracy.isNegative(),
+              "fpmath accuracy not a positive number!", &I);
+    } else if (MDString *S0 = dyn_cast_or_null<MDString>(Op0)) {
+      Assert1(S0->getString() == "fast", "wrong fpmath accuracy keyword!", &I);
+    } else {
+      Assert1(false, "invalid fpmath accuracy!", &I);
+    }
   }
 
   MDNode *MD = I.getMetadata(LLVMContext::MD_range);