[PATCH] D33908: [cmake] Enable reverse iteration by default through build macro

[Mandeep Singh Grang via Phabricator via llvm-commits]

mgrang created this revision.
Herald added a subscriber: mgorny.

Reverse iteration can be turned on, by default, by setting -DLLVM_REVERSE_ITERATION:BOOL=ON during cmake.
With this enabled, we can uncover lots of cases of non-determinism in codegen by simply running our tests (without any other change).
We can then setup a buildbot which will have this turned on by default. Initially, a lot of unit tests will fail in this configuration.
Once we start fixing non-determinism issues, we can gradually make this a blocker for patches.


Repository:
  rL LLVM

https://reviews.llvm.org/D33908

Files:
  cmake/modules/HandleLLVMOptions.cmake
  include/llvm/ADT/SmallPtrSet.h
  include/llvm/Config/abi-breaking.h.cmake


Index: include/llvm/Config/abi-breaking.h.cmake
===================================================================
--- include/llvm/Config/abi-breaking.h.cmake
+++ include/llvm/Config/abi-breaking.h.cmake
@@ -15,6 +15,9 @@
 /* Define to enable checks that alter the LLVM C++ ABI */
 #cmakedefine01 LLVM_ENABLE_ABI_BREAKING_CHECKS
 
+/* Define to enable reverse iteration of unordered llvm containers */
+#cmakedefine01 LLVM_ENABLE_REVERSE_ITERATION
+
 /* Allow selectively disabling link-time mismatch checking so that header-only
    ADT content from LLVM can be used without linking libSupport. */
 #if !LLVM_DISABLE_ABI_BREAKING_CHECKS_ENFORCING
Index: include/llvm/ADT/SmallPtrSet.h
===================================================================
--- include/llvm/ADT/SmallPtrSet.h
+++ include/llvm/ADT/SmallPtrSet.h
@@ -31,8 +31,12 @@
 
 #if LLVM_ENABLE_ABI_BREAKING_CHECKS
 template <class T = void> struct ReverseIterate { static bool value; };
+#if LLVM_ENABLE_REVERSE_ITERATION
+template <class T> bool ReverseIterate<T>::value = true;
+#else
 template <class T> bool ReverseIterate<T>::value = false;
 #endif
+#endif
 
 /// SmallPtrSetImplBase - This is the common code shared among all the
 /// SmallPtrSet<>'s, which is almost everything.  SmallPtrSet has two modes, one
Index: cmake/modules/HandleLLVMOptions.cmake
===================================================================
--- cmake/modules/HandleLLVMOptions.cmake
+++ cmake/modules/HandleLLVMOptions.cmake
@@ -101,6 +101,10 @@
   message(FATAL_ERROR "Unknown value for LLVM_ABI_BREAKING_CHECKS: \"${LLVM_ABI_BREAKING_CHECKS}\"!")
 endif()
 
+if( LLVM_REVERSE_ITERATION )
+  set( LLVM_ENABLE_REVERSE_ITERATION 1 )
+endif()
+
 if(WIN32)
   set(LLVM_HAVE_LINK_VERSION_SCRIPT 0)
   if(CYGWIN)


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