3 files changed, 49 insertions, 17 deletions

diff --git a/llvm/lib/Analysis/InstructionSimplify.cpp b/llvm/lib/Analysis/InstructionSimplify.cpp
index 11e24e5e3e9..097b99eb0a5 100644
--- a/llvm/lib/Analysis/InstructionSimplify.cpp
+++ b/llvm/lib/Analysis/InstructionSimplify.cpp
@@ -3556,14 +3556,53 @@ static bool IsIdempotent(Intrinsic::ID ID) {
 }
 
 template <typename IterTy>
-static Value *SimplifyIntrinsic(Intrinsic::ID IID, IterTy ArgBegin, IterTy ArgEnd,
+static Value *SimplifyIntrinsic(Function *F, IterTy ArgBegin, IterTy ArgEnd,
                                 const Query &Q, unsigned MaxRecurse) {
+  Intrinsic::ID IID = F->getIntrinsicID();
+  unsigned NumOperands = std::distance(ArgBegin, ArgEnd);
+  Type *ReturnType = F->getReturnType();
+
+  // Binary Ops
+  if (NumOperands == 2) {
+    Value *LHS = *ArgBegin;
+    Value *RHS = *(ArgBegin + 1);
+    if (IID == Intrinsic::usub_with_overflow ||
+        IID == Intrinsic::ssub_with_overflow) {
+      // X - X -> { 0, false }
+      if (LHS == RHS)
+        return Constant::getNullValue(ReturnType);
+
+      // X - undef -> undef
+      // undef - X -> undef
+      if (isa<UndefValue>(LHS) || isa<UndefValue>(RHS))
+        return UndefValue::get(ReturnType);
+    }
+
+    if (IID == Intrinsic::uadd_with_overflow ||
+        IID == Intrinsic::sadd_with_overflow) {
+      // X + undef -> undef
+      if (isa<UndefValue>(RHS))
+        return UndefValue::get(ReturnType);
+    }
+
+    if (IID == Intrinsic::umul_with_overflow ||
+        IID == Intrinsic::smul_with_overflow) {
+      // X * 0 -> { 0, false }
+      if (match(RHS, m_Zero()))
+        return Constant::getNullValue(ReturnType);
+
+      // X * undef -> { 0, false }
+      if (match(RHS, m_Undef()))
+        return Constant::getNullValue(ReturnType);
+    }
+  }
+
   // Perform idempotent optimizations
   if (!IsIdempotent(IID))
     return nullptr;
 
   // Unary Ops
-  if (std::distance(ArgBegin, ArgEnd) == 1)
+  if (NumOperands == 1)
     if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(*ArgBegin))
       if (II->getIntrinsicID() == IID)
         return II;
@@ -3587,9 +3626,8 @@ static Value *SimplifyCall(Value *V, IterTy ArgBegin, IterTy ArgEnd,
   if (!F)
     return nullptr;
 
-  if (Intrinsic::ID IID = F->getIntrinsicID())
-    if (Value *Ret =
-        SimplifyIntrinsic(IID, ArgBegin, ArgEnd, Q, MaxRecurse))
+  if (F->isIntrinsic())
+    if (Value *Ret = SimplifyIntrinsic(F, ArgBegin, ArgEnd, Q, MaxRecurse))
       return Ret;
 
   if (!canConstantFoldCallTo(F))
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
index 3b925eda16b..e83b9dd36ae 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
@@ -13,6 +13,7 @@
 
 #include "InstCombineInternal.h"
 #include "llvm/ADT/Statistic.h"
+#include "llvm/Analysis/InstructionSimplify.h"
 #include "llvm/Analysis/MemoryBuiltins.h"
 #include "llvm/IR/CallSite.h"
 #include "llvm/IR/Dominators.h"
@@ -323,6 +324,11 @@ static Value *SimplifyX86vperm2(const IntrinsicInst &II,
 /// the heavy lifting.
 ///
 Instruction *InstCombiner::visitCallInst(CallInst &CI) {
+  auto Args = CI.arg_operands();
+  if (Value *V = SimplifyCall(CI.getCalledValue(), Args.begin(), Args.end(), DL,
+                              TLI, DT, AC))
+    return ReplaceInstUsesWith(CI, V);
+
   if (isFreeCall(&CI, TLI))
     return visitFree(CI);
 
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
index 09ab16511e7..2dafa58d305 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
@@ -2139,10 +2139,6 @@ bool InstCombiner::OptimizeOverflowCheck(OverflowCheckFlavor OCF, Value *LHS,
   }
   // FALL THROUGH uadd into sadd
   case OCF_SIGNED_ADD: {
-    // X + undef -> undef
-    if (isa<UndefValue>(RHS))
-      return SetResult(RHS, UndefValue::get(Builder->getInt1Ty()), false);
-
     // X + 0 -> {X, false}
     if (match(RHS, m_Zero()))
       return SetResult(LHS, Builder->getFalse(), false);
@@ -2157,14 +2153,6 @@ bool InstCombiner::OptimizeOverflowCheck(OverflowCheckFlavor OCF, Value *LHS,
 
   case OCF_UNSIGNED_SUB:
   case OCF_SIGNED_SUB: {
-    // undef - X -> undef
-    if (isa<UndefValue>(LHS))
-      return SetResult(LHS, UndefValue::get(Builder->getInt1Ty()), false);
-
-    // X - undef -> undef
-    if (isa<UndefValue>(RHS))
-      return SetResult(RHS, UndefValue::get(Builder->getInt1Ty()), false);
-
     // X - 0 -> {X, false}
     if (match(RHS, m_Zero()))
       return SetResult(LHS, Builder->getFalse(), false);