[SCEVExpander] Try harder to avoid introducing inttoptr

Summary:
This fixes introduction of an incorrect inttoptr/ptrtoint pair in
the included test case which makes use of non-integral pointers. I
suspect there are more cases like this left, but this takes care of
the one I was seeing at the moment.

Reviewers: sanjoy

Subscribers: mzolotukhin, llvm-commits

Differential Revision: https://reviews.llvm.org/D33129

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@304058 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Analysis/ScalarEvolutionExpander.cpp

@@ -1305,12 +1305,17 @@ Value *SCEVExpander::expandAddRecExprLiterally(const SCEVAddRecExpr *S) {
   // Expand the core addrec. If we need post-loop scaling, force it to
   // expand to an integer type to avoid the need for additional casting.
   Type *ExpandTy = PostLoopScale ? IntTy : STy;
+  // We can't use a pointer type for the addrec if the pointer type is
+  // non-integral.
+  Type *AddRecPHIExpandTy =
+      DL.isNonIntegralPointerType(STy) ? Normalized->getType() : ExpandTy;
+
   // In some cases, we decide to reuse an existing phi node but need to truncate
   // it and/or invert the step.
   Type *TruncTy = nullptr;
   bool InvertStep = false;
-  PHINode *PN = getAddRecExprPHILiterally(Normalized, L, ExpandTy, IntTy,
-                                          TruncTy, InvertStep);
+  PHINode *PN = getAddRecExprPHILiterally(Normalized, L, AddRecPHIExpandTy,
+                                          IntTy, TruncTy, InvertStep);
 
   // Accommodate post-inc mode, if necessary.
   Value *Result;
@@ -1383,8 +1388,15 @@ Value *SCEVExpander::expandAddRecExprLiterally(const SCEVAddRecExpr *S) {
   // Re-apply any non-loop-dominating offset.
   if (PostLoopOffset) {
     if (PointerType *PTy = dyn_cast<PointerType>(ExpandTy)) {
-      const SCEV *const OffsetArray[1] = { PostLoopOffset };
-      Result = expandAddToGEP(OffsetArray, OffsetArray+1, PTy, IntTy, Result);
+      if (Result->getType()->isIntegerTy()) {
+        Value *Base = expandCodeFor(PostLoopOffset, ExpandTy);
+        const SCEV *const OffsetArray[1] = {SE.getUnknown(Result)};
+        Result = expandAddToGEP(OffsetArray, OffsetArray + 1, PTy, IntTy, Base);
+      } else {
+        const SCEV *const OffsetArray[1] = {PostLoopOffset};
+        Result =
+            expandAddToGEP(OffsetArray, OffsetArray + 1, PTy, IntTy, Result);
+      }
     } else {
       Result = InsertNoopCastOfTo(Result, IntTy);
       Result = Builder.CreateAdd(Result,

test/Transforms/LoopStrengthReduce/nonintegral.ll

@@ -0,0 +1,45 @@
+; RUN: opt -S -loop-reduce < %s | FileCheck %s
+
+; Address Space 10 is non-integral. The optimizer is not allowed to use
+; ptrtoint/inttoptr instructions. Make sure that this doesn't happen
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128-ni:10:11:12"
+target triple = "x86_64-unknown-linux-gnu"
+
+define void @japi1__unsafe_getindex_65028(i64 addrspace(10)* %arg) {
+; CHECK-NOT: inttoptr
+; CHECK-NOT: ptrtoint
+; How exactly SCEV chooses to materialize isn't all that important, as
+; long as it doesn't try to round-trip through integers. As of this writing,
+; it emits a byte-wise gep, which is fine.
+; CHECK: getelementptr i64, i64 addrspace(10)* {{.*}}, i64 {{.*}}
+top:
+  br label %L86
+
+L86:                                              ; preds = %L86, %top
+  %i.0 = phi i64 [ 0, %top ], [ %tmp, %L86 ]
+  %tmp = add i64 %i.0, 1
+  br i1 undef, label %L86, label %if29
+
+if29:                                             ; preds = %L86
+  %tmp1 = shl i64 %tmp, 1
+  %tmp2 = add i64 %tmp1, -2
+  br label %if31
+
+if31:                                             ; preds = %if38, %if29
+  %"#temp#1.sroa.0.022" = phi i64 [ 0, %if29 ], [ %tmp3, %if38 ]
+  br label %L119
+
+L119:                                             ; preds = %L119, %if31
+  %i5.0 = phi i64 [ %"#temp#1.sroa.0.022", %if31 ], [ %tmp3, %L119 ]
+  %tmp3 = add i64 %i5.0, 1
+  br i1 undef, label %L119, label %if38
+
+if38:                                             ; preds = %L119
+  %tmp4 = add i64 %tmp2, %i5.0
+  %tmp5 = getelementptr i64, i64 addrspace(10)* %arg, i64 %tmp4
+  %tmp6 = load i64, i64 addrspace(10)* %tmp5
+  br i1 undef, label %done, label %if31
+
+done:                                             ; preds = %if38
+  ret void
+}

unittests/Analysis/ScalarEvolutionTest.cpp

@@ -7,21 +7,22 @@
 //
 //===----------------------------------------------------------------------===//
 
-#include "llvm/Analysis/ScalarEvolutionExpander.h"
-#include "llvm/Analysis/ScalarEvolutionExpressions.h"
+#include "llvm/ADT/SmallVector.h"
 #include "llvm/Analysis/AssumptionCache.h"
 #include "llvm/Analysis/LoopInfo.h"
-#include "llvm/Analysis/TargetLibraryInfo.h"
-#include "llvm/ADT/SmallVector.h"
 #include "llvm/Analysis/LoopInfo.h"
+#include "llvm/Analysis/ScalarEvolutionExpander.h"
+#include "llvm/Analysis/ScalarEvolutionExpressions.h"
+#include "llvm/Analysis/TargetLibraryInfo.h"
 #include "llvm/AsmParser/Parser.h"
 #include "llvm/IR/Constants.h"
 #include "llvm/IR/Dominators.h"
 #include "llvm/IR/GlobalVariable.h"
+#include "llvm/IR/IRBuilder.h"
 #include "llvm/IR/InstIterator.h"
 #include "llvm/IR/LLVMContext.h"
-#include "llvm/IR/Module.h"
 #include "llvm/IR/LegacyPassManager.h"
+#include "llvm/IR/Module.h"
 #include "llvm/IR/Verifier.h"
 #include "llvm/Support/SourceMgr.h"
 #include "gtest/gtest.h"
@@ -853,5 +854,82 @@ TEST_F(ScalarEvolutionsTest, SCEVZeroExtendExpr) {
   Type *I128Ty = Type::getInt128Ty(Context);
   SE.getZeroExtendExpr(S, I128Ty);
 }
+
+// Make sure that SCEV doesn't introduce illegal ptrtoint/inttoptr instructions
+TEST_F(ScalarEvolutionsTest, SCEVZeroExtendExprNonIntegral) {
+  /*
+   * Create the following code:
+   * func(i64 addrspace(10)* %arg)
+   * top:
+   *  br label %L.ph
+   * L.ph:
+   *  br label %L
+   * L:
+   *  %phi = phi i64 [i64 0, %L.ph], [ %add, %L2 ]
+   *  %add = add i64 %phi2, 1
+   *  br i1 undef, label %post, label %L2
+   * post:
+   *  %gepbase = getelementptr i64 addrspace(10)* %arg, i64 1
+   *  #= %gep = getelementptr i64 addrspace(10)* %gepbase, i64 %add =#
+   *  ret void
+   *
+   * We will create the appropriate SCEV expression for %gep and expand it,
+   * then check that no inttoptr/ptrtoint instructions got inserted.
+   */
+
+  // Create a module with non-integral pointers in it's datalayout
+  Module NIM("nonintegral", Context);
+  std::string DataLayout = M.getDataLayoutStr();
+  if (!DataLayout.empty())
+    DataLayout += "-";
+  DataLayout += "ni:10";
+  NIM.setDataLayout(DataLayout);
+
+  Type *T_int1 = Type::getInt1Ty(Context);
+  Type *T_int64 = Type::getInt64Ty(Context);
+  Type *T_pint64 = T_int64->getPointerTo(10);
+
+  FunctionType *FTy =
+      FunctionType::get(Type::getVoidTy(Context), {T_pint64}, false);
+  Function *F = cast<Function>(NIM.getOrInsertFunction("foo", FTy));
+
+  Argument *Arg = &*F->arg_begin();
+
+  BasicBlock *Top = BasicBlock::Create(Context, "top", F);
+  BasicBlock *LPh = BasicBlock::Create(Context, "L.ph", F);
+  BasicBlock *L = BasicBlock::Create(Context, "L", F);
+  BasicBlock *Post = BasicBlock::Create(Context, "post", F);
+
+  IRBuilder<> Builder(Top);
+  Builder.CreateBr(LPh);
+
+  Builder.SetInsertPoint(LPh);
+  Builder.CreateBr(L);
+
+  Builder.SetInsertPoint(L);
+  PHINode *Phi = Builder.CreatePHI(T_int64, 2);
+  Value *Add = Builder.CreateAdd(Phi, ConstantInt::get(T_int64, 1), "add");
+  Builder.CreateCondBr(UndefValue::get(T_int1), L, Post);
+  Phi->addIncoming(ConstantInt::get(T_int64, 0), LPh);
+  Phi->addIncoming(Add, L);
+
+  Builder.SetInsertPoint(Post);
+  Value *GepBase = Builder.CreateGEP(Arg, {ConstantInt::get(T_int64, 1)});
+  Instruction *Ret = Builder.CreateRetVoid();
+
+  ScalarEvolution SE = buildSE(*F);
+  auto *AddRec =
+      SE.getAddRecExpr(SE.getUnknown(GepBase), SE.getConstant(T_int64, 1),
+                       LI->getLoopFor(L), SCEV::FlagNUW);
+
+  SCEVExpander Exp(SE, NIM.getDataLayout(), "expander");
+  Exp.disableCanonicalMode();
+  Exp.expandCodeFor(AddRec, T_pint64, Ret);
+
+  // Make sure none of the instructions inserted were inttoptr/ptrtoint.
+  // The verifier will check this.
+  EXPECT_FALSE(verifyFunction(*F, &errs()));
+}
+
 }  // end anonymous namespace
 }  // end namespace llvm