[BOLT][NFC] Warning for deprecated option '-reorder-blocks=cache+'

Emit warning when using deprecated option '-reorder-blocks=cache+'.
Auto switch to option '-reorder-blocks=ext-tsp'.

Test Plan:
```
ninja check-bolt
```
Added a new test cache+-deprecated.test.
Run and verify that the upstream tests are passed.

Reviewed By: rafauler, Amir, maksfb

Differential Revision: https://reviews.llvm.org/D126722

Author: nhuhuan

bolt/include/bolt/Passes/BinaryPasses.h

@@ -142,6 +142,8 @@ class ReorderBasicBlocks : public BinaryFunctionPass {
     /// LT_OPTIMIZE_CACHE piggybacks on the idea from Ispike paper (CGO '04)
     /// that suggests putting frequently executed chains first in the layout.
     LT_OPTIMIZE_CACHE,
+    // CACHE_PLUS and EXT_TSP are synonyms, emit warning of deprecation.
+    LT_OPTIMIZE_CACHE_PLUS,
     /// Block reordering guided by the extended TSP metric.
     LT_OPTIMIZE_EXT_TSP,
     /// Create clusters and use random order for them.

bolt/lib/Passes/BinaryPasses.cpp

@@ -176,13 +176,21 @@ cl::opt<bolt::ReorderBasicBlocks::LayoutType> ReorderBlocks(
         clEnumValN(bolt::ReorderBasicBlocks::LT_OPTIMIZE_CACHE, "cache",
                    "perform optimal layout prioritizing I-cache "
                    "behavior"),
-        clEnumValN(bolt::ReorderBasicBlocks::LT_OPTIMIZE_EXT_TSP, "cache+",
+        clEnumValN(bolt::ReorderBasicBlocks::LT_OPTIMIZE_CACHE_PLUS, "cache+",
                    "perform layout optimizing I-cache behavior"),
         clEnumValN(bolt::ReorderBasicBlocks::LT_OPTIMIZE_EXT_TSP, "ext-tsp",
                    "perform layout optimizing I-cache behavior"),
         clEnumValN(bolt::ReorderBasicBlocks::LT_OPTIMIZE_SHUFFLE,
                    "cluster-shuffle", "perform random layout of clusters")),
-    cl::ZeroOrMore, cl::cat(BoltOptCategory));
+    cl::ZeroOrMore, cl::cat(BoltOptCategory),
+    cl::callback([](const bolt::ReorderBasicBlocks::LayoutType &option) {
+      if (option == bolt::ReorderBasicBlocks::LT_OPTIMIZE_CACHE_PLUS) {
+        WithColor::warning()
+            << "'-reorder-blocks=cache+' is deprecated, "
+            << "please use '-reorder-blocks=ext-tsp' instead\n";
+        ReorderBlocks = bolt::ReorderBasicBlocks::LT_OPTIMIZE_EXT_TSP;
+      }
+    }));
 
 static cl::opt<unsigned>
 ReportBadLayout("report-bad-layout",

bolt/test/cache+-deprecated.test

@@ -0,0 +1,8 @@
+
+
+REQUIRES: system-linux
+
+RUN: %clangxx %p/Inputs/bolt_icf.cpp -g -Wl,-q -o %t.exe
+RUN: llvm-bolt %t.exe -reorder-blocks=cache+ -relocs -o %t 2>&1 | FileCheck %s
+
+CHECK: '-reorder-blocks=cache+' is deprecated, please use '-reorder-blocks=ext-tsp' instead