Teach SimplifyLibCalls about stpcpy.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@156815 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Transforms/Scalar/SimplifyLibCalls.cpp

@@ -458,6 +458,50 @@ struct StrCpyOpt : public LibCallOptimization {
   }
 };
 
+//===---------------------------------------===//
+// 'stpcpy' Optimizations
+
+struct StpCpyOpt: public LibCallOptimization {
+  bool OptChkCall;  // True if it's optimizing a __stpcpy_chk libcall.
+
+  StpCpyOpt(bool c) : OptChkCall(c) {}
+
+  virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
+    // Verify the "stpcpy" function prototype.
+    unsigned NumParams = OptChkCall ? 3 : 2;
+    FunctionType *FT = Callee->getFunctionType();
+    if (FT->getNumParams() != NumParams ||
+        FT->getReturnType() != FT->getParamType(0) ||
+        FT->getParamType(0) != FT->getParamType(1) ||
+        FT->getParamType(0) != B.getInt8PtrTy())
+      return 0;
+
+    // These optimizations require TargetData.
+    if (!TD) return 0;
+
+    Value *Dst = CI->getArgOperand(0), *Src = CI->getArgOperand(1);
+    if (Dst == Src)  // stpcpy(x,x)  -> x+strlen(x)
+      return B.CreateInBoundsGEP(Dst, EmitStrLen(Src, B, TD));
+
+    // See if we can get the length of the input string.
+    uint64_t Len = GetStringLength(Src);
+    if (Len == 0) return 0;
+
+    Value *LenV = ConstantInt::get(TD->getIntPtrType(*Context), Len);
+    Value *DstEnd = B.CreateGEP(Dst,
+                                ConstantInt::get(TD->getIntPtrType(*Context),
+                                                 Len - 1));
+
+    // We have enough information to now generate the memcpy call to do the
+    // copy for us.  Make a memcpy to copy the nul byte with align = 1.
+    if (OptChkCall)
+      EmitMemCpyChk(Dst, Src, LenV, CI->getArgOperand(2), B, TD);
+    else
+      B.CreateMemCpy(Dst, Src, LenV, 1);
+    return DstEnd;
+  }
+};
+
 //===---------------------------------------===//
 // 'strncpy' Optimizations
 
@@ -1474,8 +1518,11 @@ namespace {
     StringMap<LibCallOptimization*> Optimizations;
     // String and Memory LibCall Optimizations
     StrCatOpt StrCat; StrNCatOpt StrNCat; StrChrOpt StrChr; StrRChrOpt StrRChr;
-    StrCmpOpt StrCmp; StrNCmpOpt StrNCmp; StrCpyOpt StrCpy; StrCpyOpt StrCpyChk;
+    StrCmpOpt StrCmp; StrNCmpOpt StrNCmp;
-    StrNCpyOpt StrNCpy; StrLenOpt StrLen; StrPBrkOpt StrPBrk;
+    StrCpyOpt StrCpy; StrCpyOpt StrCpyChk;
+    StpCpyOpt StpCpy; StpCpyOpt StpCpyChk;
+    StrNCpyOpt StrNCpy;
+    StrLenOpt StrLen; StrPBrkOpt StrPBrk;
     StrToOpt StrTo; StrSpnOpt StrSpn; StrCSpnOpt StrCSpn; StrStrOpt StrStr;
     MemCmpOpt MemCmp; MemCpyOpt MemCpy; MemMoveOpt MemMove; MemSetOpt MemSet;
     // Math Library Optimizations
@@ -1491,7 +1538,8 @@ namespace {
     bool Modified;  // This is only used by doInitialization.
   public:
     static char ID; // Pass identification
-    SimplifyLibCalls() : FunctionPass(ID), StrCpy(false), StrCpyChk(true) {
+    SimplifyLibCalls() : FunctionPass(ID), StrCpy(false), StrCpyChk(true),
+                         StpCpy(false), StpCpyChk(true) {
       initializeSimplifyLibCallsPass(*PassRegistry::getPassRegistry());
     }
     void AddOpt(LibFunc::Func F, LibCallOptimization* Opt);
@@ -1542,6 +1590,7 @@ void SimplifyLibCalls::InitOptimizations() {
   Optimizations["strncmp"] = &StrNCmp;
   Optimizations["strcpy"] = &StrCpy;
   Optimizations["strncpy"] = &StrNCpy;
+  Optimizations["stpcpy"] = &StpCpy;
   Optimizations["strlen"] = &StrLen;
   Optimizations["strpbrk"] = &StrPBrk;
   Optimizations["strtol"] = &StrTo;
@@ -1561,6 +1610,7 @@ void SimplifyLibCalls::InitOptimizations() {
 
   // _chk variants of String and Memory LibCall Optimizations.
   Optimizations["__strcpy_chk"] = &StrCpyChk;
+  Optimizations["__stpcpy_chk"] = &StpCpyChk;
 
   // Math Library Optimizations
   Optimizations["cosf"] = &Cos;
@@ -1746,6 +1796,7 @@ void SimplifyLibCalls::inferPrototypeAttributes(Function &F) {
                Name == "strtold" ||
                Name == "strncat" ||
                Name == "strncpy" ||
+               Name == "stpncpy" ||
                Name == "strtoull") {
       if (FTy->getNumParams() < 2 ||
           !FTy->getParamType(1)->isPointerTy())
@@ -2406,10 +2457,6 @@ bool SimplifyLibCalls::doInitialization(Module &M) {
 //   * sqrt(Nroot(x)) -> pow(x,1/(2*N))
 //   * sqrt(pow(x,y)) -> pow(|x|,y*0.5)
 //
-// stpcpy:
-//   * stpcpy(str, "literal") ->
-//           llvm.memcpy(str,"literal",strlen("literal")+1,1)
-//
 // strchr:
 //   * strchr(p, 0) -> strlen(p)
 // tan, tanf, tanl:

test/Transforms/SimplifyLibCalls/StpCpy.ll

@@ -0,0 +1,43 @@
+; Test that the StpCpyOptimizer works correctly
+; RUN: opt < %s -simplify-libcalls -S | FileCheck %s
+
+; This transformation requires the pointer size, as it assumes that size_t is
+; the size of a pointer.
+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"
+
+@hello = constant [6 x i8] c"hello\00"
+
+declare i8* @stpcpy(i8*, i8*)
+
+declare i8* @__stpcpy_chk(i8*, i8*, i32) nounwind
+
+declare i32 @llvm.objectsize.i32(i8*, i1, i32) nounwind readonly
+
+define i32 @t1() {
+; CHECK: @t1
+  %target = alloca [1024 x i8]
+  %arg1 = getelementptr [1024 x i8]* %target, i32 0, i32 0
+  %arg2 = getelementptr [6 x i8]* @hello, i32 0, i32 0
+  %rslt1 = call i8* @stpcpy( i8* %arg1, i8* %arg2 )
+; CHECK: @llvm.memcpy.p0i8.p0i8.i32
+  ret i32 0
+}
+
+define i32 @t2() {
+; CHECK: @t2
+  %target = alloca [1024 x i8]
+  %arg1 = getelementptr [1024 x i8]* %target, i32 0, i32 0
+  %arg2 = getelementptr [6 x i8]* @hello, i32 0, i32 0
+  %tmp1 = call i32 @llvm.objectsize.i32(i8* %arg1, i1 false, i32 0)
+  %rslt1 = call i8* @__stpcpy_chk(i8* %arg1, i8* %arg2, i32 %tmp1)
+; CHECK: @__memcpy_chk
+  ret i32 0
+}
+
+define i8* @t3(i8* %arg) {
+; CHECK: @t3
+  %stpcpy = tail call i8* @stpcpy(i8* %arg, i8* %arg)
+; CHECK: [[LEN:%[a-z]+]] = call i32 @strlen(i8* %arg)
+; CHECK-NEXT: getelementptr inbounds i8* %arg, i32 [[LEN]]
+  ret i8* %stpcpy
+}