IR: Add Value::reverseUseList()

I'm going to use this to improve `verify-uselistorder`.  Part of PR5680.

llvm-svn: 214594

1 files changed, 43 insertions, 0 deletions

diff --git a/llvm/unittests/IR/UseTest.cpp b/llvm/unittests/IR/UseTest.cpp
index 980175c..fa73fe7 100644
--- a/llvm/unittests/IR/UseTest.cpp
+++ b/llvm/unittests/IR/UseTest.cpp
@@ -66,4 +66,47 @@ TEST(UseTest, sort) {
   ASSERT_EQ(8u, I);
 }
 
+TEST(UseTest, reverse) {
+  LLVMContext C;
+
+  const char *ModuleString = "define void @f(i32 %x) {\n"
+                             "entry:\n"
+                             "  %v0 = add i32 %x, 0\n"
+                             "  %v2 = add i32 %x, 2\n"
+                             "  %v5 = add i32 %x, 5\n"
+                             "  %v1 = add i32 %x, 1\n"
+                             "  %v3 = add i32 %x, 3\n"
+                             "  %v7 = add i32 %x, 7\n"
+                             "  %v6 = add i32 %x, 6\n"
+                             "  %v4 = add i32 %x, 4\n"
+                             "  ret void\n"
+                             "}\n";
+  SMDiagnostic Err;
+  char vnbuf[8];
+  Module *M = ParseAssemblyString(ModuleString, nullptr, Err, C);
+  Function *F = M->getFunction("f");
+  ASSERT_TRUE(F);
+  ASSERT_TRUE(F->arg_begin() != F->arg_end());
+  Argument &X = *F->arg_begin();
+  ASSERT_EQ("x", X.getName());
+
+  X.sortUseList([](const Use &L, const Use &R) {
+    return L.getUser()->getName() < R.getUser()->getName();
+  });
+  unsigned I = 0;
+  for (User *U : X.users()) {
+    snprintf(vnbuf, sizeof(vnbuf), "v%u", I++);
+    EXPECT_EQ(vnbuf, U->getName());
+  }
+  ASSERT_EQ(8u, I);
+
+  X.reverseUseList();
+  I = 0;
+  for (User *U : X.users()) {
+    snprintf(vnbuf, sizeof(vnbuf), "v%u", (7 - I++));
+    EXPECT_EQ(vnbuf, U->getName());
+  }
+  ASSERT_EQ(8u, I);
+}
+
 } // end anonymous namespace