Propagate Undef in llvm.cos Intrinsic

Summary:
The llvm cos intrinsic currently does not propagate undef's. This change
transforms cos(undef) to null value or 0.

There are 2 test cases added as well.

Patch by Anna Thomas!

Reviewers: sanjoy

Subscribers: majnemer, llvm-commits

Differential Revision: http://reviews.llvm.org/D18863

llvm-svn: 265825

2 files changed, 31 insertions, 0 deletions

diff --git a/llvm/lib/Analysis/ConstantFolding.cpp b/llvm/lib/Analysis/ConstantFolding.cpp
index 017d897def7..d87a0800262 100644
--- a/llvm/lib/Analysis/ConstantFolding.cpp
+++ b/llvm/lib/Analysis/ConstantFolding.cpp
@@ -1443,6 +1443,11 @@ Constant *ConstantFoldScalarCall(StringRef Name, unsigned IntrinsicID, Type *Ty,
                                  ArrayRef<Constant *> Operands,
                                  const TargetLibraryInfo *TLI) {
   if (Operands.size() == 1) {
+    if (isa<UndefValue>(Operands[0])) {
+      // cosine(arg) is between -1 and 1. cosine(invalid arg) is NaN
+      if (IntrinsicID == Intrinsic::cos)
+        return Constant::getNullValue(Ty);
+    }
     if (ConstantFP *Op = dyn_cast<ConstantFP>(Operands[0])) {
       if (IntrinsicID == Intrinsic::convert_to_fp16) {
         APFloat Val(Op->getValueAPF());
diff --git a/llvm/test/Transforms/InstCombine/cos-intrinsic.ll b/llvm/test/Transforms/InstCombine/cos-intrinsic.ll
new file mode 100644
index 00000000000..b4d07cf8047
--- /dev/null
+++ b/llvm/test/Transforms/InstCombine/cos-intrinsic.ll
@@ -0,0 +1,26 @@
+; RUN: opt < %s -instcombine -S | FileCheck %s
+; This test makes sure that the undef is propagated for the cos instrinsic
+
+declare double    @llvm.cos.f64(double %Val)
+declare float     @llvm.cos.f32(float %Val)
+
+; Function Attrs: nounwind readnone
+define double @test1() {
+; CHECK-LABEL: define double @test1(
+; CHECK-NEXT: ret double 0.000000e+00
+  %1 = call double @llvm.cos.f64(double undef)
+  ret double %1
+}
+
+
+; Function Attrs: nounwind readnone
+define float @test2(float %d) {
+; CHECK-LABEL: define float @test2(
+; CHECK-NEXT: %cosval = call float @llvm.cos.f32(float %d)
+   %cosval   = call float @llvm.cos.f32(float %d)
+   %cosval2  = call float @llvm.cos.f32(float undef)
+   %fsum   = fadd float %cosval2, %cosval
+   ret float %fsum
+; CHECK-NEXT: %fsum
+; CHECK: ret float %fsum
+}