stop llvm-reduce from introducing undefs

Differential Revision: https://reviews.llvm.org/D128317

Author: regehr

llvm/test/tools/llvm-reduce/operands-to-args.ll

@@ -20,7 +20,7 @@
 ; INTERESTING: store i32 %[[KEEP]], i32* @GlobalKeep, align 4
 
 ; INTERESTING-LABEL: define void @func_caller() {
-; REDUCED:             call void @func(i32 21, i32* undef, i32* undef, float* undef)
+; REDUCED:             call void @func(i32 21, i32* null, i32* null, float* null)
 
 
 @Global = global i32 42

llvm/test/tools/llvm-reduce/remove-all-of-multiple-args.ll

@@ -6,7 +6,7 @@ define i32 @t(i32 %a0, i32 %a1, i32 %a2) {
 ; CHECK-FINAL: () {
 ;
 ; CHECK-INTERESTINGNESS: ret i32
-; CHECK-FINAL: ret i32 undef
+; CHECK-FINAL: ret i32 0
 
   ret i32 %a1
 }

llvm/test/tools/llvm-reduce/remove-args-used-by-ret.ll

@@ -8,7 +8,7 @@ define i32 @t(i32 %a0, i32 %a1, i32 %a2) {
 ; CHECK-FINAL-NOT: %a1
 ;
 ; CHECK-INTERESTINGNESS: ret i32
-; CHECK-FINAL: ret i32 undef
+; CHECK-FINAL: ret i32 0
 
   ret i32 %a1
 }

llvm/test/tools/llvm-reduce/remove-bbs-ret-nonvoid.ll

@@ -13,7 +13,7 @@ define i32 @main(i1 %c) {
 ; CHECK-NEXT:    br label %interesting2
 
 ; CHECK-LABEL: interesting2:
-; CHECK-NEXT:    ret i32 undef
+; CHECK-NEXT:    ret i32 0
 
 interesting:
   br label %interesting2

llvm/test/tools/llvm-reduce/remove-bbs-unwinded-to.ll

@@ -25,7 +25,7 @@ bb1:
 ; CHECK-ALL: bb3:
 bb3:
 ; CHECK-INTERESTINGNESS: call void @did_not_throw(i32
-; CHECK-FINAL: call void @did_not_throw(i32 undef)
+; CHECK-FINAL: call void @did_not_throw(i32 0)
 ; CHECK-ALL: br label %bb4
   call void @did_not_throw(i32 %i0)
   br label %bb4

llvm/test/tools/llvm-reduce/remove-global-vars.ll

@@ -1,5 +1,5 @@
 ; Test that llvm-reduce can remove uninteresting Global Variables as well as
-; their direct uses (which in turn are replaced with 'undef').
+; their direct uses (which in turn are replaced with '0').
 
 ; RUN: llvm-reduce --delta-passes=global-variables,global-initializers --test FileCheck --test-arg --check-prefixes=CHECK-ALL,CHECK-INTERESTINGNESS --test-arg %s --test-arg --input-file %s -o %t
 ; RUN: cat %t | FileCheck --check-prefixes=CHECK-ALL,CHECK-FINAL --implicit-check-not=uninteresting %s
@@ -31,11 +31,11 @@ entry:
   %0 = load i32, i32* @uninteresting, align 4
 
   ; CHECK-INTERESTINGNESS: store i32 {{.*}}, i32* @interesting, align 4
-  ; CHECK-FINAL: store i32 undef, i32* @interesting, align 4
+  ; CHECK-FINAL: store i32 0, i32* @interesting, align 4
   store i32 %0, i32* @interesting, align 4
 
   ; CHECK-INTERESTINGNESS: store i32 {{.*}}, i32* @interesting3, align 4
-  ; CHECK-FINAL: store i32 undef, i32* @interesting3, align 4
+  ; CHECK-FINAL: store i32 0, i32* @interesting3, align 4
   store i32 %0, i32* @interesting3, align 4
 
   ; CHECK-ALL: load i32, i32* @interesting, align 4

llvm/test/tools/llvm-reduce/remove-operands-fp.ll

@@ -1,8 +1,5 @@
 ; Test that llvm-reduce can reduce floating point operands
 ;
-; RUN: llvm-reduce --abort-on-invalid-reduction --delta-passes=operands-undef --test FileCheck --test-arg --check-prefixes=CHECK-INTERESTINGNESS --test-arg %s --test-arg --input-file %s -o %t
-; RUN: FileCheck --check-prefixes=CHECK,UNDEF %s < %t
-
 ; RUN: llvm-reduce --abort-on-invalid-reduction --delta-passes=operands-one --test FileCheck --test-arg --check-prefixes=CHECK-INTERESTINGNESS --test-arg %s --test-arg --input-file %s -o %t
 ; RUN: FileCheck --check-prefixes=CHECK,ONE %s < %t
 
@@ -28,19 +25,6 @@
 
 ; CHECK-LABEL: define void @foo(
 
-; UNDEF: %fadd0 = fadd float %arg0, undef
-; UNDEF: %fadd1 = fadd float undef, undef
-; UNDEF: %fadd2 = fadd float undef, 0.000000e+00
-; UNDEF: %fadd3 = fadd float undef, 1.000000e+00
-; UNDEF: %fadd4 = fadd float undef, 0x7FF8000000000000
-; UNDEF: %fadd5 = fadd float undef, undef
-; UNDEF: %fadd6 = fadd <2 x float> %arg2, undef
-; UNDEF: %fadd7 = fadd <2 x float> undef, undef
-; UNDEF: %fadd8 = fadd <2 x float> undef, zeroinitializer
-; UNDEF: %fadd9 = fadd <2 x float> undef, <float 1.000000e+00, float 1.000000e+00>
-; UNDEF: %fadd10 = fadd <2 x float> undef, undef
-; UNDEF: %fadd11 = fadd <2 x float> undef, <float 0x7FF8000000000000, float 0x7FF8000000000000>
-
 
 ; ONE: %fadd0 = fadd float %arg0, 1.000000e+00
 ; ONE: %fadd1 = fadd float 1.000000e+00, 1.000000e+00

llvm/test/tools/llvm-reduce/remove-operands.ll

@@ -1,7 +1,5 @@
 ; Test that llvm-reduce can reduce operands
 ;
-; RUN: llvm-reduce --abort-on-invalid-reduction --delta-passes=operands-undef --test FileCheck --test-arg --check-prefixes=CHECK-INTERESTINGNESS --test-arg %s --test-arg --input-file %s -o %t
-; RUN: cat %t | FileCheck %s --check-prefixes=CHECK,UNDEF
 ; RUN: llvm-reduce --abort-on-invalid-reduction --delta-passes=operands-one --test FileCheck --test-arg --check-prefixes=CHECK-INTERESTINGNESS --test-arg %s --test-arg --input-file %s -o %t
 ; RUN: cat %t | FileCheck %s --check-prefixes=CHECK,ONE
 ; RUN: llvm-reduce --abort-on-invalid-reduction --delta-passes=operands-zero --test FileCheck --test-arg --check-prefixes=CHECK-INTERESTINGNESS --test-arg %s --test-arg --input-file %s -o %t
@@ -24,10 +22,6 @@ declare void @llvm.foo(metadata)
 define i32 @main(%t* %a, i32 %a2) {
 
 ; CHECK-LABEL: lb1:
-; UNDEF: inttoptr i16 0
-; UNDEF: inttoptr i16 1
-; UNDEF: inttoptr i16 2
-; UNDEF: inttoptr i16 undef
 ; ONE: inttoptr i16 0
 ; ONE: inttoptr i16 1
 ; ONE: inttoptr i16 1
@@ -47,7 +41,6 @@ lb1:
   br label %lb2
 
 ; CHECK-LABEL: lb2:
-; UNDEF: ret i32 undef
 ; ONE: ret i32 1
 ; ZERO: ret i32 0
 lb2:

llvm/tools/llvm-reduce/CMakeLists.txt

@@ -21,6 +21,7 @@ add_llvm_tool(llvm-reduce
   ReducerWorkItem.cpp
   TestRunner.cpp
   deltas/Delta.cpp
+  deltas/Utils.cpp
   deltas/ReduceAliases.cpp
   deltas/ReduceArguments.cpp
   deltas/ReduceAttributes.cpp

llvm/tools/llvm-reduce/DeltaManager.cpp

@@ -66,7 +66,6 @@ static cl::opt<std::string>
   DELTA_PASS("simplify-instructions", simplifyInstructionsDeltaPass)           \
   DELTA_PASS("operands-zero", reduceOperandsZeroDeltaPass)                     \
   DELTA_PASS("operands-one", reduceOperandsOneDeltaPass)                       \
-  DELTA_PASS("operands-undef", reduceOperandsUndefDeltaPass)                   \
   DELTA_PASS("operands-to-args", reduceOperandsToArgsDeltaPass)                \
   DELTA_PASS("operands-skip", reduceOperandsSkipDeltaPass)                     \
   DELTA_PASS("operand-bundles", reduceOperandBundesDeltaPass)                  \

llvm/tools/llvm-reduce/deltas/ReduceArguments.cpp

@@ -13,6 +13,7 @@
 
 #include "ReduceArguments.h"
 #include "Delta.h"
+#include "Utils.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/IR/Constants.h"
 #include "llvm/IR/Instructions.h"
@@ -79,7 +80,7 @@ static void extractArgumentsFromModule(Oracle &O, Module &Program) {
       if (!ArgsToKeep.count(&A)) {
         // By adding undesired arguments to the VMap, CloneFunction will remove
         // them from the resulting Function
-        VMap[&A] = UndefValue::get(A.getType());
+        VMap[&A] = getDefaultValue(A.getType());
         for (auto *U : A.users())
           if (auto *I = dyn_cast<Instruction>(*&U))
             InstToDelete.push_back(I);
@@ -89,7 +90,7 @@ static void extractArgumentsFromModule(Oracle &O, Module &Program) {
       if (!V)
         continue;
       auto *I = cast<Instruction>(V);
-      I->replaceAllUsesWith(UndefValue::get(I->getType()));
+      I->replaceAllUsesWith(getDefaultValue(I->getType()));
       if (!I->isTerminator())
         I->eraseFromParent();
     }

llvm/tools/llvm-reduce/deltas/ReduceBasicBlocks.cpp

@@ -12,6 +12,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "ReduceBasicBlocks.h"
+#include "Utils.h"
 #include "llvm/ADT/DenseSet.h"
 #include "llvm/IR/BasicBlock.h"
 #include "llvm/IR/Constants.h"
@@ -43,7 +44,7 @@ static void replaceBranchTerminator(BasicBlock &BB,
   if (auto *IndBI = dyn_cast<IndirectBrInst>(Term))
     Address = IndBI->getAddress();
 
-  Term->replaceAllUsesWith(UndefValue::get(Term->getType()));
+  Term->replaceAllUsesWith(getDefaultValue(Term->getType()));
   Term->eraseFromParent();
 
   if (ChunkSuccessors.empty()) {
@@ -62,7 +63,7 @@ static void replaceBranchTerminator(BasicBlock &BB,
     // If that fails then resort to replacing with a ret.
     auto *FnRetTy = BB.getParent()->getReturnType();
     ReturnInst::Create(BB.getContext(),
-                       FnRetTy->isVoidTy() ? nullptr : UndefValue::get(FnRetTy),
+                       FnRetTy->isVoidTy() ? nullptr : getDefaultValue(FnRetTy),
                        &BB);
     return;
   }
@@ -87,7 +88,7 @@ removeUninterestingBBsFromSwitch(SwitchInst &SwInst,
   if (!BBsToKeep.count(SwInst.getDefaultDest())) {
     auto *FnRetTy = SwInst.getParent()->getParent()->getReturnType();
     ReturnInst::Create(SwInst.getContext(),
-                       FnRetTy->isVoidTy() ? nullptr : UndefValue::get(FnRetTy),
+                       FnRetTy->isVoidTy() ? nullptr : getDefaultValue(FnRetTy),
                        SwInst.getParent());
     SwInst.eraseFromParent();
   } else
@@ -133,7 +134,7 @@ static void extractBasicBlocksFromModule(Oracle &O, Module &Program) {
   for (auto &BB : BBsToDelete) {
     // Instructions might be referenced in other BBs
     for (auto &I : *BB)
-      I.replaceAllUsesWith(UndefValue::get(I.getType()));
+      I.replaceAllUsesWith(getDefaultValue(I.getType()));
     if (BB->getParent()->size() == 1) {
       // this is the last basic block of the function, thus we must also make
       // sure to remove comdat and set linkage to external

llvm/tools/llvm-reduce/deltas/ReduceFunctions.cpp

@@ -14,6 +14,7 @@
 
 #include "ReduceFunctions.h"
 #include "Delta.h"
+#include "Utils.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/IR/Constants.h"
 #include "llvm/IR/Instructions.h"
@@ -42,8 +43,8 @@ static void extractFunctionsFromModule(Oracle &O, Module &Program) {
 
   // And finally, we can actually delete them.
   for (Function &F : FuncsToRemove) {
-    // Replace all *still* remaining uses with undef.
-    F.replaceAllUsesWith(UndefValue::get(F.getType()));
+    // Replace all *still* remaining uses with the default value.
+    F.replaceAllUsesWith(getDefaultValue(F.getType()));
     // And finally, fully drop it.
     F.eraseFromParent();
   }

llvm/tools/llvm-reduce/deltas/ReduceGlobalVars.cpp

@@ -12,6 +12,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "ReduceGlobalVars.h"
+#include "Utils.h"
 #include "llvm/IR/Constants.h"
 #include <set>
 
@@ -40,7 +41,7 @@ static void extractGVsFromModule(Oracle &O, Module &Program) {
         if (auto *Inst = dyn_cast<Instruction>(U))
           InstToRemove.push_back(Inst);
 
-      GV.replaceAllUsesWith(UndefValue::get(GV.getType()));
+      GV.replaceAllUsesWith(getDefaultValue(GV.getType()));
       ToRemove.push_back(&GV);
     }
 
@@ -49,7 +50,7 @@ static void extractGVsFromModule(Oracle &O, Module &Program) {
     if (!V)
       continue;
     auto *Inst = cast<Instruction>(V);
-    Inst->replaceAllUsesWith(UndefValue::get(Inst->getType()));
+    Inst->replaceAllUsesWith(getDefaultValue(Inst->getType()));
     Inst->eraseFromParent();
   }
 

llvm/tools/llvm-reduce/deltas/ReduceInstructions.cpp

@@ -12,6 +12,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "ReduceInstructions.h"
+#include "Utils.h"
 #include "llvm/IR/Constants.h"
 
 using namespace llvm;
@@ -42,7 +43,7 @@ static void extractInstrFromModule(Oracle &O, Module &Program) {
     for (auto &BB : F)
       for (auto &Inst : BB)
         if (!InstToKeep.count(&Inst)) {
-          Inst.replaceAllUsesWith(UndefValue::get(Inst.getType()));
+          Inst.replaceAllUsesWith(getDefaultValue(Inst.getType()));
           InstToDelete.push_back(&Inst);
         }
 

llvm/tools/llvm-reduce/deltas/ReduceOperands.cpp

@@ -62,19 +62,6 @@ static bool shouldReduceOperand(Use &Op) {
   return true;
 }
 
-void llvm::reduceOperandsUndefDeltaPass(TestRunner &Test) {
-  errs() << "*** Reducing Operands to undef...\n";
-  auto ReduceValue = [](Use &Op) -> Value * {
-    if (!shouldReduceOperand(Op))
-      return nullptr;
-    // Don't replace existing ConstantData Uses.
-    return isa<ConstantData>(*Op) ? nullptr : UndefValue::get(Op->getType());
-  };
-  runDeltaPass(Test, [ReduceValue](Oracle &O, Module &Program) {
-    extractOperandsFromModule(O, Program, ReduceValue);
-  });
-}
-
 void llvm::reduceOperandsOneDeltaPass(TestRunner &Test) {
   errs() << "*** Reducing Operands to one...\n";
   auto ReduceValue = [](Use &Op) -> Value * {

llvm/tools/llvm-reduce/deltas/ReduceOperands.h

@@ -12,7 +12,6 @@
 #include "Delta.h"
 
 namespace llvm {
-void reduceOperandsUndefDeltaPass(TestRunner &Test);
 void reduceOperandsOneDeltaPass(TestRunner &Test);
 void reduceOperandsZeroDeltaPass(TestRunner &Test);
 } // namespace llvm

llvm/tools/llvm-reduce/deltas/ReduceOperandsSkip.cpp

@@ -61,7 +61,7 @@ static bool shouldReduceOperand(Use &Op) {
 static int classifyReductivePower(Value *V) {
   if (auto *C = dyn_cast<ConstantData>(V)) {
     if (isa<UndefValue>(V))
-      return 4;
+      return -2;
     if (C->isNullValue())
       return 7;
     if (C->isOneValue())

llvm/tools/llvm-reduce/deltas/ReduceOperandsToArgs.cpp

@@ -8,6 +8,7 @@
 
 #include "ReduceOperandsToArgs.h"
 #include "Delta.h"
+#include "Utils.h"
 #include "llvm/ADT/Sequence.h"
 #include "llvm/IR/Constants.h"
 #include "llvm/IR/InstIterator.h"
@@ -67,10 +68,10 @@ static void replaceFunctionCalls(Function *OldF, Function *NewF) {
   // Call arguments for NewF.
   SmallVector<Value *> Args(NewF->arg_size(), nullptr);
 
-  // Fill up the additional parameters with undef values.
+  // Fill up the additional parameters with default values.
   for (auto ArgIdx : llvm::seq<size_t>(OldF->arg_size(), NewF->arg_size())) {
     Type *NewArgTy = NewF->getArg(ArgIdx)->getType();
-    Args[ArgIdx] = UndefValue::get(NewArgTy);
+    Args[ArgIdx] = getDefaultValue(NewArgTy);
   }
 
   for (CallBase *CI : Callers) {

llvm/tools/llvm-reduce/deltas/ReduceSpecialGlobals.cpp

@@ -16,6 +16,7 @@
 
 #include "ReduceSpecialGlobals.h"
 #include "Delta.h"
+#include "Utils.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/IR/Constants.h"
 #include "llvm/IR/GlobalValue.h"
@@ -29,7 +30,7 @@ static StringRef SpecialGlobalNames[] = {"llvm.used", "llvm.compiler.used"};
 static void extractSpecialGlobalsFromModule(Oracle &O, Module &Program) {
   for (StringRef Name : SpecialGlobalNames) {
     if (auto *Used = Program.getNamedGlobal(Name)) {
-      Used->replaceAllUsesWith(UndefValue::get(Used->getType()));
+      Used->replaceAllUsesWith(getDefaultValue(Used->getType()));
       Used->eraseFromParent();
     }
   }

llvm/tools/llvm-reduce/deltas/Utils.cpp

@@ -0,0 +1,20 @@
+//===- Utils.cpp - llvm-reduce utility functions --------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file contains some utility functions supporting llvm-reduce.
+//
+//===----------------------------------------------------------------------===//
+
+#include "Utils.h"
+#include "llvm/IR/Constants.h"
+
+using namespace llvm;
+
+Value *llvm::getDefaultValue(Type *T) {
+  return T->isVoidTy() ? PoisonValue::get(T) : Constant::getNullValue(T);
+}

llvm/tools/llvm-reduce/deltas/Utils.h

@@ -0,0 +1,24 @@
+//===- Utils.h - llvm-reduce utility functions ----------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file contains some utility functions supporting llvm-reduce.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_TOOLS_LLVM_REDUCE_DELTAS_UTILS_H
+#define LLVM_TOOLS_LLVM_REDUCE_DELTAS_UTILS_H
+
+#include "llvm/IR/Value.h"
+
+namespace llvm {
+
+Value *getDefaultValue(Type *T);
+
+} // namespace llvm
+
+#endif