vendor/llvm/llvm-trunk-r240225

1 files changed, 17 insertions, 2 deletions

diff --git a/lib/Analysis/InstructionSimplify.cpp b/lib/Analysis/InstructionSimplify.cpp
index ec56d888dc2f..12e406bb1a2d 100644
--- a/lib/Analysis/InstructionSimplify.cpp
+++ b/lib/Analysis/InstructionSimplify.cpp
@@ -854,8 +854,8 @@ static Value *SimplifyFSubInst(Value *Op0, Value *Op1, FastMathFlags FMF,
       return X;
   }
 
-  // fsub nnan ninf x, x ==> 0.0
-  if (FMF.noNaNs() && FMF.noInfs() && Op0 == Op1)
+  // fsub nnan x, x ==> 0.0
+  if (FMF.noNaNs() && Op0 == Op1)
     return Constant::getNullValue(Op0->getType());
 
   return nullptr;
@@ -1126,6 +1126,21 @@ static Value *SimplifyFDivInst(Value *Op0, Value *Op1, FastMathFlags FMF,
   if (FMF.noNaNs() && FMF.noSignedZeros() && match(Op0, m_AnyZero()))
     return Op0;
 
+  if (FMF.noNaNs()) {
+    // X / X -> 1.0 is legal when NaNs are ignored.
+    if (Op0 == Op1)
+      return ConstantFP::get(Op0->getType(), 1.0);
+
+    // -X /  X -> -1.0 and
+    //  X / -X -> -1.0 are legal when NaNs are ignored.
+    // We can ignore signed zeros because +-0.0/+-0.0 is NaN and ignored.
+    if ((BinaryOperator::isFNeg(Op0, /*IgnoreZeroSign=*/true) &&
+         BinaryOperator::getFNegArgument(Op0) == Op1) ||
+        (BinaryOperator::isFNeg(Op1, /*IgnoreZeroSign=*/true) &&
+         BinaryOperator::getFNegArgument(Op1) == Op0))
+      return ConstantFP::get(Op0->getType(), -1.0);
+  }
+
   return nullptr;
 }