[InstCombine] Handle saddo always overflow

Followup to D60483: Handle AlwaysOverflow conditions for saddo as
well.

Differential Revision: https://reviews.llvm.org/D60497

llvm-svn: 358095

diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
index 7ec7535..bc99b17 100644 (file)
--- a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
@@ -3973,15 +3973,15 @@ bool InstCombiner::OptimizeOverflowCheck(OverflowCheckFlavor OCF, Value *LHS,
       if (OR == OverflowResult::NeverOverflows)
         return SetResult(Builder.CreateNUWAdd(LHS, RHS), Builder.getFalse(),
                          true);
-
-      if (OR == OverflowResult::AlwaysOverflows)
-        return SetResult(Builder.CreateAdd(LHS, RHS), Builder.getTrue(), true);
     } else {
       OR = computeOverflowForSignedAdd(LHS, RHS, &OrigI);
       if (OR == OverflowResult::NeverOverflows)
         return SetResult(Builder.CreateNSWAdd(LHS, RHS), Builder.getFalse(),
                          true);
     }
+
+    if (OR == OverflowResult::AlwaysOverflows)
+      return SetResult(Builder.CreateAdd(LHS, RHS), Builder.getTrue(), true);
     break;
   }
 

diff --git a/llvm/test/Transforms/InstCombine/with_overflow.ll b/llvm/test/Transforms/InstCombine/with_overflow.ll
index d5a727e..af9b133 100644 (file)
--- a/llvm/test/Transforms/InstCombine/with_overflow.ll
+++ b/llvm/test/Transforms/InstCombine/with_overflow.ll
@@ -568,8 +568,9 @@ define { i8, i1 } @sadd_always_overflow(i8 %x) nounwind {
 ; CHECK-LABEL: @sadd_always_overflow(
 ; CHECK-NEXT:    [[C:%.*]] = icmp sgt i8 [[X:%.*]], 100
 ; CHECK-NEXT:    [[Y:%.*]] = select i1 [[C]], i8 [[X]], i8 100
-; CHECK-NEXT:    [[A:%.*]] = call { i8, i1 } @llvm.sadd.with.overflow.i8(i8 [[Y]], i8 28)
-; CHECK-NEXT:    ret { i8, i1 } [[A]]
+; CHECK-NEXT:    [[A:%.*]] = add nuw i8 [[Y]], 28
+; CHECK-NEXT:    [[TMP1:%.*]] = insertvalue { i8, i1 } { i8 undef, i1 true }, i8 [[A]], 0
+; CHECK-NEXT:    ret { i8, i1 } [[TMP1]]
 ;
   %c = icmp sgt i8 %x, 100
   %y = select i1 %c, i8 %x, i8 100