Reland "[LLVM] Add IRNormalizer Pass"

llvm/docs/Passes.rst

@@ -543,6 +543,14 @@ variables with initializers are marked as internal.
 An interprocedural variant of :ref:`Sparse Conditional Constant Propagation
 <passes-sccp>`.
 
+``ir-normalizer``: Transforms IR into a normal form that's easier to diff
+----------------------------------------------------------------------------
+
+This pass aims to transform LLVM Modules into a normal form by reordering and
+renaming instructions while preserving the same semantics. The normalizer makes
+it easier to spot semantic differences while diffing two modules which have
+undergone two different passes.
+
 ``jump-threading``: Jump Threading
 ----------------------------------
 

llvm/docs/ReleaseNotes.md

@@ -42,6 +42,11 @@ point (e.g. maybe you would like to give an example of the
 functionality, or simply have a lot to talk about), see the comment below
 for adding a new subsection. -->
 
+* Added a new IRNormalizer pass which aims to transform LLVM modules into
+  a normal form by reordering and renaming instructions while preserving the
+  same semantics. The normalizer makes it easier to spot semantic differences
+  when diffing two modules which have undergone different passes.
+
 * ...
 
 <!-- If you would like to document a larger change, then you can add a

llvm/include/llvm/Transforms/Utils/IRNormalizer.h

@@ -0,0 +1,15 @@
+#ifndef LLVM_TRANSFORMS_UTILS_IRNORMALIZER_H
+#define LLVM_TRANSFORMS_UTILS_IRNORMALIZER_H
+
+#include "llvm/IR/PassManager.h"
+
+namespace llvm {
+
+/// IRNormalizer aims to transform LLVM IR into normal form.
+struct IRNormalizerPass : public PassInfoMixin<IRNormalizerPass> {
+  PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM) const;
+};
+
+} // namespace llvm
+
+#endif // LLVM_TRANSFORMS_UTILS_IRNORMALIZER_H

llvm/lib/Passes/PassBuilder.cpp

@@ -306,9 +306,9 @@
 #include "llvm/Transforms/Utils/EntryExitInstrumenter.h"
 #include "llvm/Transforms/Utils/FixIrreducible.h"
 #include "llvm/Transforms/Utils/HelloWorld.h"
+#include "llvm/Transforms/Utils/IRNormalizer.h"
 #include "llvm/Transforms/Utils/InjectTLIMappings.h"
 #include "llvm/Transforms/Utils/InstructionNamer.h"
-#include "llvm/Transforms/Utils/Instrumentation.h"
 #include "llvm/Transforms/Utils/LCSSA.h"
 #include "llvm/Transforms/Utils/LibCallsShrinkWrap.h"
 #include "llvm/Transforms/Utils/LoopSimplify.h"

llvm/lib/Passes/PassRegistry.def

@@ -415,6 +415,7 @@ FUNCTION_PASS("move-auto-init", MoveAutoInitPass())
 FUNCTION_PASS("nary-reassociate", NaryReassociatePass())
 FUNCTION_PASS("newgvn", NewGVNPass())
 FUNCTION_PASS("no-op-function", NoOpFunctionPass())
+FUNCTION_PASS("normalize", IRNormalizerPass())
 FUNCTION_PASS("objc-arc", ObjCARCOptPass())
 FUNCTION_PASS("objc-arc-contract", ObjCARCContractPass())
 FUNCTION_PASS("objc-arc-expand", ObjCARCExpandPass())

llvm/lib/Transforms/Utils/CMakeLists.txt

@@ -37,6 +37,7 @@ add_llvm_component_library(LLVMTransformUtils
   InstructionNamer.cpp
   Instrumentation.cpp
   IntegerDivision.cpp
+  IRNormalizer.cpp
   LCSSA.cpp
   LibCallsShrinkWrap.cpp
   Local.cpp