fix the quotient returned by sdivrem() for the case when LHS is negative and RHS is positive

based on a patch by Preston Briggs, with some modifications

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@157231 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 31 insertions, 2 deletions

diff --git a/include/llvm/ADT/APInt.h b/include/llvm/ADT/APInt.h
index 4101989976..eb7192cb95 100644
--- a/include/llvm/ADT/APInt.h
+++ b/include/llvm/ADT/APInt.h
@@ -817,9 +817,10 @@ public:
     if (LHS.isNegative()) {
       if (RHS.isNegative())
         APInt::udivrem(-LHS, -RHS, Quotient, Remainder);
-      else
+      else {
         APInt::udivrem(-LHS, RHS, Quotient, Remainder);
-      Quotient = -Quotient;
+        Quotient = -Quotient;
+      }
       Remainder = -Remainder;
     } else if (RHS.isNegative()) {
       APInt::udivrem(LHS, -RHS, Quotient, Remainder);
diff --git a/unittests/ADT/APIntTest.cpp b/unittests/ADT/APIntTest.cpp
index 89b8aa94e4..49d7e703de 100644
--- a/unittests/ADT/APIntTest.cpp
+++ b/unittests/ADT/APIntTest.cpp
@@ -171,6 +171,34 @@ TEST(APIntTest, i1) {
   EXPECT_EQ(zero, neg_one.srem(one));
   EXPECT_EQ(zero, neg_one.urem(one));
   EXPECT_EQ(zero, one.srem(neg_one));
+
+  // sdivrem
+  {
+  APInt q(8, 0);
+  APInt r(8, 0);
+  APInt one(8, 1);
+  APInt two(8, 2);
+  APInt nine(8, 9);
+  APInt four(8, 4);
+
+  EXPECT_EQ(nine.srem(two), one);
+  EXPECT_EQ(nine.srem(-two), one);
+  EXPECT_EQ((-nine).srem(two), -one);
+  EXPECT_EQ((-nine).srem(-two), -one);
+
+  APInt::sdivrem(nine, two, q, r);
+  EXPECT_EQ(four, q);
+  EXPECT_EQ(one, r);
+  APInt::sdivrem(-nine, two, q, r);
+  EXPECT_EQ(-four, q);
+  EXPECT_EQ(-one, r);
+  APInt::sdivrem(nine, -two, q, r);
+  EXPECT_EQ(-four, q);
+  EXPECT_EQ(one, r);
+  APInt::sdivrem(-nine, -two, q, r);
+  EXPECT_EQ(four, q);
+  EXPECT_EQ(-one, r);
+  }
 }
 
 TEST(APIntTest, fromString) {