Identify and simplify idempotent intrinsics. Test case included.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@174650 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Analysis/InstructionSimplify.cpp b/lib/Analysis/InstructionSimplify.cpp
index 34ff64d..4a3c74e 100644
--- a/lib/Analysis/InstructionSimplify.cpp
+++ b/lib/Analysis/InstructionSimplify.cpp
@@ -2925,6 +2925,37 @@
RecursionLimit);
}
+static bool IsIdempotent(Intrinsic::ID ID) {
+ switch (ID) {
+ default: return false;
+
+ // Unary idempotent: f(f(x)) = f(x)
+ case Intrinsic::fabs:
+ case Intrinsic::floor:
+ case Intrinsic::ceil:
+ case Intrinsic::trunc:
+ case Intrinsic::rint:
+ case Intrinsic::nearbyint:
+ return true;
+ }
+}
+
+template <typename IterTy>
+static Value *SimplifyIntrinsic(Intrinsic::ID IID, IterTy ArgBegin, IterTy ArgEnd,
+ const Query &Q, unsigned MaxRecurse) {
+ // Perform idempotent optimizations
+ if (!IsIdempotent(IID))
+ return 0;
+
+ // Unary Ops
+ if (std::distance(ArgBegin, ArgEnd) == 1)
+ if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(*ArgBegin))
+ if (II->getIntrinsicID() == IID)
+ return II;
+
+ return 0;
+}
+
template <typename IterTy>
static Value *SimplifyCall(Value *V, IterTy ArgBegin, IterTy ArgEnd,
const Query &Q, unsigned MaxRecurse) {
@@ -2941,6 +2972,11 @@
if (!F)
return 0;
+ if (unsigned IID = F->getIntrinsicID())
+ if (Value *Ret =
+ SimplifyIntrinsic((Intrinsic::ID) IID, ArgBegin, ArgEnd, Q, MaxRecurse))
+ return Ret;
+
if (!canConstantFoldCallTo(F))
return 0;