Commit 56edbc93 authored by Meador Inge's avatar Meador Inge
Browse files

instcombine: Migrate strstr optimizations 

This patch migrates the strstr optimizations from the simplify-libcalls
pass into the instcombine library call simplifier.

llvm-svn: 167682
parent 76fc1a47

llvm/lib/Transforms/Scalar/SimplifyLibCalls.cpp

+3 −88
Original line number Diff line number Diff line
@@ -99,94 +99,11 @@ static bool CallHasFloatingPointArgument(const CallInst *CI) { 
  return false;

}



/// IsOnlyUsedInEqualityComparison - Return true if it is only used in equality

/// comparisons with With.

static bool IsOnlyUsedInEqualityComparison(Value *V, Value *With) {

  for (Value::use_iterator UI = V->use_begin(), E = V->use_end();

       UI != E; ++UI) {

    if (ICmpInst *IC = dyn_cast<ICmpInst>(*UI))

      if (IC->isEquality() && IC->getOperand(1) == With)

        continue;

    // Unknown instruction.

    return false;

  }

  return true;

}



//===----------------------------------------------------------------------===//

// String and Memory LibCall Optimizations

// Memory LibCall Optimizations

//===----------------------------------------------------------------------===//



namespace {

//===---------------------------------------===//

// 'strstr' Optimizations



struct StrStrOpt : public LibCallOptimization {

  virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {

    FunctionType *FT = Callee->getFunctionType();

    if (FT->getNumParams() != 2 ||

        !FT->getParamType(0)->isPointerTy() ||

        !FT->getParamType(1)->isPointerTy() ||

        !FT->getReturnType()->isPointerTy())

      return 0;



    // fold strstr(x, x) -> x.

    if (CI->getArgOperand(0) == CI->getArgOperand(1))

      return B.CreateBitCast(CI->getArgOperand(0), CI->getType());



    // fold strstr(a, b) == a -> strncmp(a, b, strlen(b)) == 0

    if (TD && IsOnlyUsedInEqualityComparison(CI, CI->getArgOperand(0))) {

      Value *StrLen = EmitStrLen(CI->getArgOperand(1), B, TD, TLI);

      if (!StrLen)

        return 0;

      Value *StrNCmp = EmitStrNCmp(CI->getArgOperand(0), CI->getArgOperand(1),

                                   StrLen, B, TD, TLI);

      if (!StrNCmp)

        return 0;

      for (Value::use_iterator UI = CI->use_begin(), UE = CI->use_end();

           UI != UE; ) {

        ICmpInst *Old = cast<ICmpInst>(*UI++);

        Value *Cmp = B.CreateICmp(Old->getPredicate(), StrNCmp,

                                  ConstantInt::getNullValue(StrNCmp->getType()),

                                  "cmp");

        Old->replaceAllUsesWith(Cmp);

        Old->eraseFromParent();

      }

      return CI;

    }



    // See if either input string is a constant string.

    StringRef SearchStr, ToFindStr;

    bool HasStr1 = getConstantStringInfo(CI->getArgOperand(0), SearchStr);

    bool HasStr2 = getConstantStringInfo(CI->getArgOperand(1), ToFindStr);



    // fold strstr(x, "") -> x.

    if (HasStr2 && ToFindStr.empty())

      return B.CreateBitCast(CI->getArgOperand(0), CI->getType());



    // If both strings are known, constant fold it.

    if (HasStr1 && HasStr2) {

      std::string::size_type Offset = SearchStr.find(ToFindStr);



      if (Offset == StringRef::npos) // strstr("foo", "bar") -> null

        return Constant::getNullValue(CI->getType());



      // strstr("abcd", "bc") -> gep((char*)"abcd", 1)

      Value *Result = CastToCStr(CI->getArgOperand(0), B);

      Result = B.CreateConstInBoundsGEP1_64(Result, Offset, "strstr");

      return B.CreateBitCast(Result, CI->getType());

    }



    // fold strstr(x, "y") -> strchr(x, 'y').

    if (HasStr2 && ToFindStr.size() == 1) {

      Value *StrChr= EmitStrChr(CI->getArgOperand(0), ToFindStr[0], B, TD, TLI);

      return StrChr ? B.CreateBitCast(StrChr, CI->getType()) : 0;

    }

    return 0;

  }

};





//===---------------------------------------===//

// 'memcmp' Optimizations
@@ -969,8 +886,7 @@ namespace { 
    TargetLibraryInfo *TLI;



    StringMap<LibCallOptimization*> Optimizations;

    // String and Memory LibCall Optimizations

    StrStrOpt StrStr;

    // Memory LibCall Optimizations

    MemCmpOpt MemCmp; MemCpyOpt MemCpy; MemMoveOpt MemMove; MemSetOpt MemSet;

    // Math Library Optimizations

    CosOpt Cos; PowOpt Pow; Exp2Opt Exp2;
@@ -1037,8 +953,7 @@ void SimplifyLibCalls::AddOpt(LibFunc::Func F1, LibFunc::Func F2, 
/// Optimizations - Populate the Optimizations map with all the optimizations

/// we know.

void SimplifyLibCalls::InitOptimizations() {

  // String and Memory LibCall Optimizations

  Optimizations["strstr"] = &StrStr;

  // Memory LibCall Optimizations

  Optimizations["memcmp"] = &MemCmp;

  AddOpt(LibFunc::memcpy, &MemCpy);

  Optimizations["memmove"] = &MemMove;

llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp

+80 −0
Original line number Diff line number Diff line
@@ -86,6 +86,20 @@ static bool isOnlyUsedInZeroEqualityComparison(Value *V) { 
  return true;

}



/// isOnlyUsedInEqualityComparison - Return true if it is only used in equality

/// comparisons with With.

static bool isOnlyUsedInEqualityComparison(Value *V, Value *With) {

  for (Value::use_iterator UI = V->use_begin(), E = V->use_end();

       UI != E; ++UI) {

    if (ICmpInst *IC = dyn_cast<ICmpInst>(*UI))

      if (IC->isEquality() && IC->getOperand(1) == With)

        continue;

    // Unknown instruction.

    return false;

  }

  return true;

}



//===----------------------------------------------------------------------===//

// Fortified Library Call Optimizations

//===----------------------------------------------------------------------===//
@@ -836,6 +850,70 @@ struct StrCSpnOpt : public LibCallOptimization { 
  }

};



struct StrStrOpt : public LibCallOptimization {

  virtual Value *callOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {

    FunctionType *FT = Callee->getFunctionType();

    if (FT->getNumParams() != 2 ||

        !FT->getParamType(0)->isPointerTy() ||

        !FT->getParamType(1)->isPointerTy() ||

        !FT->getReturnType()->isPointerTy())

      return 0;



    // fold strstr(x, x) -> x.

    if (CI->getArgOperand(0) == CI->getArgOperand(1))

      return B.CreateBitCast(CI->getArgOperand(0), CI->getType());



    // fold strstr(a, b) == a -> strncmp(a, b, strlen(b)) == 0

    if (TD && isOnlyUsedInEqualityComparison(CI, CI->getArgOperand(0))) {

      Value *StrLen = EmitStrLen(CI->getArgOperand(1), B, TD, TLI);

      if (!StrLen)

        return 0;

      Value *StrNCmp = EmitStrNCmp(CI->getArgOperand(0), CI->getArgOperand(1),

                                   StrLen, B, TD, TLI);

      if (!StrNCmp)

        return 0;

      for (Value::use_iterator UI = CI->use_begin(), UE = CI->use_end();

           UI != UE; ) {

        ICmpInst *Old = cast<ICmpInst>(*UI++);

        Value *Cmp = B.CreateICmp(Old->getPredicate(), StrNCmp,

                                  ConstantInt::getNullValue(StrNCmp->getType()),

                                  "cmp");

        LCS->replaceAllUsesWith(Old, Cmp);

      }

      return CI;

    }



    // See if either input string is a constant string.

    StringRef SearchStr, ToFindStr;

    bool HasStr1 = getConstantStringInfo(CI->getArgOperand(0), SearchStr);

    bool HasStr2 = getConstantStringInfo(CI->getArgOperand(1), ToFindStr);



    // fold strstr(x, "") -> x.

    if (HasStr2 && ToFindStr.empty())

      return B.CreateBitCast(CI->getArgOperand(0), CI->getType());



    // If both strings are known, constant fold it.

    if (HasStr1 && HasStr2) {

      std::string::size_type Offset = SearchStr.find(ToFindStr);



      if (Offset == StringRef::npos) // strstr("foo", "bar") -> null

        return Constant::getNullValue(CI->getType());



      // strstr("abcd", "bc") -> gep((char*)"abcd", 1)

      Value *Result = CastToCStr(CI->getArgOperand(0), B);

      Result = B.CreateConstInBoundsGEP1_64(Result, Offset, "strstr");

      return B.CreateBitCast(Result, CI->getType());

    }



    // fold strstr(x, "y") -> strchr(x, 'y').

    if (HasStr2 && ToFindStr.size() == 1) {

      Value *StrChr= EmitStrChr(CI->getArgOperand(0), ToFindStr[0], B, TD, TLI);

      return StrChr ? B.CreateBitCast(StrChr, CI->getType()) : 0;

    }

    return 0;

  }

};



} // End anonymous namespace.



namespace llvm {
@@ -869,6 +947,7 @@ class LibCallSimplifierImpl { 
  StrToOpt StrTo;

  StrSpnOpt StrSpn;

  StrCSpnOpt StrCSpn;

  StrStrOpt StrStr;



  void initOptimizations();

  void addOpt(LibFunc::Func F, LibCallOptimization* Opt);
@@ -914,6 +993,7 @@ void LibCallSimplifierImpl::initOptimizations() { 
  addOpt(LibFunc::strtoull, &StrTo);

  addOpt(LibFunc::strspn, &StrSpn);

  addOpt(LibFunc::strcspn, &StrCSpn);

  addOpt(LibFunc::strstr, &StrStr);

}



Value *LibCallSimplifierImpl::optimizeCall(CallInst *CI) {

llvm/test/Transforms/InstCombine/strstr-1.ll

0 → 100644
+65 −0
Original line number Diff line number Diff line 
; Test that the strstr library call simplifier works correctly.

;

; RUN: opt < %s -instcombine -S | FileCheck %s



target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"



@.str = private constant [1 x i8] zeroinitializer

@.str1 = private constant [2 x i8] c"a\00"

@.str2 = private constant [6 x i8] c"abcde\00"

@.str3 = private constant [4 x i8] c"bcd\00"



declare i8* @strstr(i8*, i8*)



; Check strstr(str, "") -> str.



define i8* @test_simplify1(i8* %str) {

; CHECK: @test_simplify1

  %pat = getelementptr inbounds [1 x i8]* @.str, i32 0, i32 0

  %ret = call i8* @strstr(i8* %str, i8* %pat)

  ret i8* %ret

; CHECK-NEXT: ret i8* %str

}



; Check strstr(str, "a") -> strchr(str, 'a').



define i8* @test_simplify2(i8* %str) {

; CHECK: @test_simplify2

  %pat = getelementptr inbounds [2 x i8]* @.str1, i32 0, i32 0

  %ret = call i8* @strstr(i8* %str, i8* %pat)

  ret i8* %ret

; CHECK-NEXT: @strchr(i8* %str, i32 97)

}



; Check strstr("abcde", "bcd") -> "abcde" + 1.



define i8* @test_simplify3() {

; CHECK: @test_simplify3

  %str = getelementptr inbounds [6 x i8]* @.str2, i32 0, i32 0

  %pat = getelementptr inbounds [4 x i8]* @.str3, i32 0, i32 0

  %ret = call i8* @strstr(i8* %str, i8* %pat)

  ret i8* %ret

; CHECK-NEXT: getelementptr inbounds ([6 x i8]* @.str2, i64 0, i64 1)

}



; Check strstr(str, str) -> str.



define i8* @test_simplify4(i8* %str) {

; CHECK: @test_simplify4

  %ret = call i8* @strstr(i8* %str, i8* %str)

  ret i8* %ret

; CHECK-NEXT: ret i8* %str

}



; Check strstr(str, pat) == str -> strncmp(str, pat, strlen(str)) == 0.



define i1 @test_simplify5(i8* %str, i8* %pat) {

; CHECK: @test_simplify5

  %ret = call i8* @strstr(i8* %str, i8* %pat)

  %cmp = icmp eq i8* %ret, %str

  ret i1 %cmp

; CHECK: [[LEN:%[a-z]+]] = call {{i[0-9]+}} @strlen(i8* %pat)

; CHECK: [[NCMP:%[a-z]+]] = call {{i[0-9]+}} @strncmp(i8* %str, i8* %pat, {{i[0-9]+}} [[LEN]])

; CHECK: icmp eq {{i[0-9]+}} [[NCMP]], 0

; CHECK: ret i1

}

llvm/test/Transforms/InstCombine/strstr-2.ll

0 → 100644
+18 −0
Original line number Diff line number Diff line 
; Test that the strstr library call simplifier works correctly.

;

; RUN: opt < %s -instcombine -S | FileCheck %s



target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"



@null = private constant [1 x i8] zeroinitializer



declare i8 @strstr(i8*, i8*)



define i8 @test_no_simplify1(i8* %str) {

; CHECK: @test_no_simplify1

  %pat = getelementptr inbounds [1 x i8]* @null, i32 0, i32 0

  %ret = call i8 @strstr(i8* %str, i8* %pat)

; CHECK-NEXT: call i8 @strstr

  ret i8 %ret

; CHECK-NEXT: ret i8 %ret

}

llvm/test/Transforms/SimplifyLibCalls/StrStr.ll

deleted100644 → 0
+0 −60
Original line number Diff line number Diff line 
; RUN: opt < %s -simplify-libcalls -S | FileCheck %s

; PR5783



target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:128:128-n8:16:32"

target triple = "i386-apple-darwin9.0"



@.str = private constant [1 x i8] zeroinitializer ; <[1 x i8]*> [#uses=1]

@.str1 = private constant [2 x i8] c"a\00"        ; <[2 x i8]*> [#uses=1]

@.str2 = private constant [6 x i8] c"abcde\00"    ; <[6 x i8]*> [#uses=1]

@.str3 = private constant [4 x i8] c"bcd\00"      ; <[4 x i8]*> [#uses=1]



define i8* @test1(i8* %P) nounwind readonly {

entry:

  %call = tail call i8* @strstr(i8* %P, i8* getelementptr inbounds ([1 x i8]* @.str, i32 0, i32 0)) nounwind ; <i8*> [#uses=1]

  ret i8* %call

; strstr(P, "") -> P

; CHECK: @test1

; CHECK: ret i8* %P

}



declare i8* @strstr(i8*, i8* nocapture) nounwind readonly



define i8* @test2(i8* %P) nounwind readonly {

entry:

  %call = tail call i8* @strstr(i8* %P, i8* getelementptr inbounds ([2 x i8]* @.str1, i32 0, i32 0)) nounwind ; <i8*> [#uses=1]

  ret i8* %call

; strstr(P, "a") -> strchr(P, 'a')

; CHECK: @test2

; CHECK: @strchr(i8* %P, i32 97)

}



define i8* @test3(i8* nocapture %P) nounwind readonly {

entry:

  %call = tail call i8* @strstr(i8* getelementptr inbounds ([6 x i8]* @.str2, i32 0, i32 0), i8* getelementptr inbounds ([4 x i8]* @.str3, i32 0, i32 0)) nounwind ; <i8*> [#uses=1]

  ret i8* %call

; strstr("abcde", "bcd") -> "abcde"+1

; CHECK: @test3

; CHECK: getelementptr inbounds ([6 x i8]* @.str2, i32 0, i64 1)

}



define i8* @test4(i8* %P) nounwind readonly {

entry:

  %call = tail call i8* @strstr(i8* %P, i8* %P) nounwind ; <i8*> [#uses=1]

  ret i8* %call

; strstr(P, P) -> P

; CHECK: @test4

; CHECK: ret i8* %P

}



define i1 @test5(i8* %P, i8* %Q) nounwind readonly {

entry:

  %call = tail call i8* @strstr(i8* %P, i8* %Q) nounwind ; <i8*> [#uses=1]

  %cmp = icmp eq i8* %call, %P

  ret i1 %cmp

; CHECK: @test5

; CHECK: [[LEN:%[a-z]+]] = call {{i[0-9]+}} @strlen(i8* %Q)

; CHECK: [[NCMP:%[a-z]+]] = call {{i[0-9]+}} @strncmp(i8* %P, i8* %Q, {{i[0-9]+}} [[LEN]])

; CHECK: icmp eq {{i[0-9]+}} [[NCMP]], 0

; CHECK: ret i1

}