Stub out a new lazy value info pass, which will eventually

vend value constraint information to the optimizer.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@86767 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/Analysis/LazyValueInfo.h

@@ -0,0 +1,43 @@
+//===- LazyValueInfo.h - Value constraint analysis --------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines the interface for lazy computation of value constraint
+// information.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_ANALYSIS_LIVEVALUES_H
+#define LLVM_ANALYSIS_LIVEVALUES_H
+
+#include "llvm/Pass.h"
+
+namespace llvm {
+
+/// LazyValueInfo - This pass computes, caches, and vends lazy value constraint
+/// information.
+class LazyValueInfo : public FunctionPass {
+public:
+  static char ID;
+  LazyValueInfo();
+
+  virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+    AU.setPreservesAll();
+  }
+  virtual void releaseMemory();
+  
+  virtual bool runOnFunction(Function &F) {
+    // Fully lazy.
+    return false;
+  }
+};
+
+}  // end namespace llvm
+
+#endif
+

include/llvm/Analysis/Passes.h

@@ -139,6 +139,12 @@ namespace llvm {
   // createLiveValuesPass - This creates an instance of the LiveValues pass.
   //
   FunctionPass *createLiveValuesPass();
+  
+  //===--------------------------------------------------------------------===//
+  //
+  /// createLazyValueInfoPass - This creates an instance of the LazyValueInfo
+  /// pass.
+  FunctionPass *createLazyValueInfoPass();
 
   //===--------------------------------------------------------------------===//
   //

include/llvm/LinkAllPasses.h

@@ -82,6 +82,7 @@ namespace {
       (void) llvm::createInternalizePass(false);
       (void) llvm::createLCSSAPass();
       (void) llvm::createLICMPass();
+      (void) llvm::createLazyValueInfoPass();
       (void) llvm::createLiveValuesPass();
       (void) llvm::createLoopDependenceAnalysisPass();
       (void) llvm::createLoopExtractorPass();

lib/Analysis/CMakeLists.txt

@@ -18,6 +18,7 @@ add_llvm_library(LLVMAnalysis
   InstructionSimplify.cpp
   Interval.cpp
   IntervalPartition.cpp
+  LazyValueInfo.cpp
   LibCallAliasAnalysis.cpp
   LibCallSemantics.cpp
   LiveValues.cpp

lib/Analysis/LazyValueInfo.cpp

@@ -0,0 +1,31 @@
+//===- LazyValueInfo.cpp - Value constraint analysis ----------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines the interface for lazy computation of value constraint
+// information.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Analysis/LazyValueInfo.h"
+using namespace llvm;
+
+char LazyValueInfo::ID = 0;
+static RegisterPass<LazyValueInfo>
+X("lazy-value-info", "Lazy Value Information Analysis", false, true);
+
+namespace llvm {
+  FunctionPass *createLazyValueInfoPass() { return new LazyValueInfo(); }
+}
+
+LazyValueInfo::LazyValueInfo() : FunctionPass(&ID) {
+}
+
+void LazyValueInfo::releaseMemory() {
+  
+}

test/Transforms/JumpThreading/basic.ll

@@ -284,3 +284,29 @@ F2:
 }
 
 
+
+
+;;; Duplicate condition to avoid xor of cond.
+define i32 @test10(i1 %cond, i1 %cond2) {
+Entry:
+; CHECK: @test10
+	%v1 = call i32 @f1()
+	br i1 %cond, label %Merge, label %F1
+
+F1:
+	br label %Merge
+
+Merge:
+	%B = phi i1 [true, %Entry], [%cond2, %F1]
+        %M = icmp eq i32 %v1, 192
+        %N = xor i1 %B, %M
+	br i1 %N, label %T2, label %F2
+
+T2:
+	ret i32 123
+
+F2:
+	ret i32 %v1
+}
+
+