commit efc3d1dfaae18a3da135504098174002d42cc76f
author Sanjay Patel <spatel@rotateright.com> Tue Nov 20 17:05:55 2018 +0000
committer Sanjay Patel <spatel@rotateright.com> Tue Nov 20 17:05:55 2018 +0000
tree 24f2ae943bd3ad513cd3500468d987348a546df9
parent 537a5bfb7f1e9b85d615df95d7facacb5fb1638b

[ConstantFolding] Add support for saturating add/sub

Support saturating add/sub in constant folding, based on the APInt methods introduced in D54332.

Patch by: @nikic (Nikita Popov)

Differential Revision: https://reviews.llvm.org/D54531

llvm-svn: 347328

llvm/lib/Analysis/ConstantFolding.cpp

diff --git a/llvm/lib/Analysis/ConstantFolding.cpp b/llvm/lib/Analysis/ConstantFolding.cpp
index 92b0555..fded0c6 100644
--- a/llvm/lib/Analysis/ConstantFolding.cpp
+++ b/llvm/lib/Analysis/ConstantFolding.cpp
@@ -1399,6 +1399,10 @@
   case Intrinsic::usub_with_overflow:
   case Intrinsic::smul_with_overflow:
   case Intrinsic::umul_with_overflow:
+  case Intrinsic::sadd_sat:
+  case Intrinsic::uadd_sat:
+  case Intrinsic::ssub_sat:
+  case Intrinsic::usub_sat:
   case Intrinsic::convert_from_fp16:
   case Intrinsic::convert_to_fp16:
   case Intrinsic::bitreverse:
@@ -2019,6 +2023,14 @@
           };
           return ConstantStruct::get(cast<StructType>(Ty), Ops);
         }
+        case Intrinsic::uadd_sat:
+          return ConstantInt::get(Ty, Op1->getValue().uadd_sat(Op2->getValue()));
+        case Intrinsic::sadd_sat:
+          return ConstantInt::get(Ty, Op1->getValue().sadd_sat(Op2->getValue()));
+        case Intrinsic::usub_sat:
+          return ConstantInt::get(Ty, Op1->getValue().usub_sat(Op2->getValue()));
+        case Intrinsic::ssub_sat:
+          return ConstantInt::get(Ty, Op1->getValue().ssub_sat(Op2->getValue()));
         case Intrinsic::cttz:
           if (Op2->isOne() && Op1->isZero()) // cttz(0, 1) is undef.
             return UndefValue::get(Ty);