[Comgr][Cache] Enable the cache by default (llvm#1084)

Author: jmmartinez

amd/comgr/README.md

@@ -120,10 +120,10 @@ and eviction policy can be manipulated through specific environment variables.
 If an issue arises during cache initialization, the execution will proceed with
 the cache turned off.
 
-By default, the cache is turned off, set the environment variable
-`AMD_COMGR_CACHE=1` to enable it.
+By default, the cache is enabled.
 
-* `AMD_COMGR_CACHE`: When unset or set to 0, the cache is turned off.
+* `AMD_COMGR_CACHE`: When unset or set to a value different than "0", the cache is enabled.
+  Disabled when set to "0".
 * `AMD_COMGR_CACHE_DIR`: If assigned a non-empty value, that value is used as
   the path for cache storage. If the variable is unset or set to an empty string `""`,
   it is directed to "$XDG_CACHE_HOME/comgr" (which defaults to

amd/comgr/src/comgr-env.cpp

@@ -81,10 +81,9 @@ StringRef getCachePolicy() {
 }
 
 StringRef getCacheDirectory() {
-  // By default the cache is deactivated. We hope to remove this variable in the
-  // future.
+  // By default the cache is enabled
   static const char *Enable = std::getenv("AMD_COMGR_CACHE");
-  bool CacheDisabled = !Enable || StringRef(Enable) == "0";
+  bool CacheDisabled = StringRef(Enable) == "0";
   if (CacheDisabled)
     return "";
 

amd/comgr/test-lit/compile-minimal-test-cached.cl

@@ -3,7 +3,9 @@
 // RUN: unset AMD_COMGR_CACHE
 // RUN: AMD_COMGR_CACHE_DIR=%t.cache compile-minimal-test %S/compile-minimal-test.cl %t.bin
 // RUN: llvm-objdump -d %t.bin | FileCheck %S/compile-minimal-test.cl
-// RUN: [ ! -d %t.cache ]
+// RUN: [ -d %t.cache ]
+//
+// RUN: rm -fr %t.cache
 //
 // RUN: export AMD_COMGR_CACHE=0
 // RUN: AMD_COMGR_CACHE_DIR=%t.cache compile-minimal-test %S/compile-minimal-test.cl %t.bin