[ConstantRange] Add API for intrinsics (NFC)

This adds a common API for compute constant ranges of intrinsics.
The intention here is that
a) we can reuse the same code across different passes that handle
   constant ranges, i.e. this can be reused in SCCP
b) we only have to add knowledge about supported intrinsics to
   ConstantRange, not any consumers.

Differential Revision: https://reviews.llvm.org/D84587

1 files changed, 30 insertions, 0 deletions

diff --git a/llvm/lib/IR/ConstantRange.cpp b/llvm/lib/IR/ConstantRange.cpp
index eabaaa2..26cff91 100644
--- a/llvm/lib/IR/ConstantRange.cpp
+++ b/llvm/lib/IR/ConstantRange.cpp
@@ -26,6 +26,7 @@
 #include "llvm/IR/Constants.h"
 #include "llvm/IR/InstrTypes.h"
 #include "llvm/IR/Instruction.h"
+#include "llvm/IR/Intrinsics.h"
 #include "llvm/IR/Metadata.h"
 #include "llvm/IR/Operator.h"
 #include "llvm/Support/Compiler.h"
@@ -835,6 +836,35 @@ ConstantRange ConstantRange::overflowingBinaryOp(Instruction::BinaryOps BinOp,
   }
 }
 
+bool ConstantRange::isIntrinsicSupported(Intrinsic::ID IntrinsicID) {
+  switch (IntrinsicID) {
+  case Intrinsic::uadd_sat:
+  case Intrinsic::usub_sat:
+  case Intrinsic::sadd_sat:
+  case Intrinsic::ssub_sat:
+    return true;
+  default:
+    return false;
+  }
+}
+
+ConstantRange ConstantRange::intrinsic(Intrinsic::ID IntrinsicID,
+                                       ArrayRef<ConstantRange> Ops) {
+  switch (IntrinsicID) {
+  case Intrinsic::uadd_sat:
+    return Ops[0].uadd_sat(Ops[1]);
+  case Intrinsic::usub_sat:
+    return Ops[0].usub_sat(Ops[1]);
+  case Intrinsic::sadd_sat:
+    return Ops[0].sadd_sat(Ops[1]);
+  case Intrinsic::ssub_sat:
+    return Ops[0].ssub_sat(Ops[1]);
+  default:
+    assert(!isIntrinsicSupported(IntrinsicID) && "Shouldn't be supported");
+    llvm_unreachable("Unsupported intrinsic");
+  }
+}
+
 ConstantRange
 ConstantRange::add(const ConstantRange &Other) const {
   if (isEmptySet() || Other.isEmptySet())