From 000dbccfc68e92305854b273104eb8e7530aa949 Mon Sep 17 00:00:00 2001
From: Meador Inge <meadori@codesourcery.com>
Date: Thu, 18 Oct 2012 18:12:40 +0000
Subject: instcombine: Migrate strcpy optimizations

This patch migrates the strcpy optimizations from the simplify-libcalls pass
into the instcombine library call simplifier.  Note also that StrCpyChkOpt
has been updated with a few simplifications that were being done in the
simplify-libcalls version of StrCpyOpt, but not in the migrated implementation
of StrCpyOpt.  There is no reason to overload StrCpyOpt with fortified and
regular simplifications in the new model since there is already a dedicated
simplifier for __strcpy_chk.

llvm-svn: 166198
---
 llvm/lib/Transforms/Scalar/SimplifyLibCalls.cpp | 47 +------------------------
 1 file changed, 1 insertion(+), 46 deletions(-)

(limited to 'llvm/lib/Transforms/Scalar/SimplifyLibCalls.cpp')

diff --git a/llvm/lib/Transforms/Scalar/SimplifyLibCalls.cpp b/llvm/lib/Transforms/Scalar/SimplifyLibCalls.cpp
index d86c4cbc9f6..90efa8ae0e0 100644
--- a/llvm/lib/Transforms/Scalar/SimplifyLibCalls.cpp
+++ b/llvm/lib/Transforms/Scalar/SimplifyLibCalls.cpp
@@ -134,47 +134,6 @@ static bool IsOnlyUsedInEqualityComparison(Value *V, Value *With) {
 //===----------------------------------------------------------------------===//
 
 namespace {
-//===---------------------------------------===//
-// 'strcpy' Optimizations
-
-struct StrCpyOpt : public LibCallOptimization {
-  bool OptChkCall;  // True if it's optimizing a __strcpy_chk libcall.
-
-  StrCpyOpt(bool c) : OptChkCall(c) {}
-
-  virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
-    // Verify the "strcpy" 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;
-
-    Value *Dst = CI->getArgOperand(0), *Src = CI->getArgOperand(1);
-    if (Dst == Src)      // strcpy(x,x)  -> x
-      return Src;
-
-    // These optimizations require DataLayout.
-    if (!TD) return 0;
-
-    // See if we can get the length of the input string.
-    uint64_t Len = GetStringLength(Src);
-    if (Len == 0) return 0;
-
-    // We have enough information to now generate the memcpy call to do the
-    // concatenation for us.  Make a memcpy to copy the nul byte with align = 1.
-    if (!OptChkCall ||
-        !EmitMemCpyChk(Dst, Src,
-                       ConstantInt::get(TD->getIntPtrType(*Context), Len),
-                       CI->getArgOperand(2), B, TD, TLI))
-      B.CreateMemCpy(Dst, Src,
-                     ConstantInt::get(TD->getIntPtrType(*Context), Len), 1);
-    return Dst;
-  }
-};
-
 //===---------------------------------------===//
 // 'stpcpy' Optimizations
 
@@ -1275,7 +1234,6 @@ namespace {
 
     StringMap<LibCallOptimization*> Optimizations;
     // String and Memory LibCall Optimizations
-    StrCpyOpt StrCpy; StrCpyOpt StrCpyChk;
     StpCpyOpt StpCpy; StpCpyOpt StpCpyChk;
     StrNCpyOpt StrNCpy;
     StrLenOpt StrLen; StrPBrkOpt StrPBrk;
@@ -1295,8 +1253,7 @@ namespace {
     bool Modified;  // This is only used by doInitialization.
   public:
     static char ID; // Pass identification
-    SimplifyLibCalls() : FunctionPass(ID), StrCpy(false), StrCpyChk(true),
-                         StpCpy(false), StpCpyChk(true),
+    SimplifyLibCalls() : FunctionPass(ID), StpCpy(false), StpCpyChk(true),
                          UnaryDoubleFP(false), UnsafeUnaryDoubleFP(true) {
       initializeSimplifyLibCallsPass(*PassRegistry::getPassRegistry());
     }
@@ -1348,7 +1305,6 @@ void SimplifyLibCalls::AddOpt(LibFunc::Func F1, LibFunc::Func F2,
 /// we know.
 void SimplifyLibCalls::InitOptimizations() {
   // String and Memory LibCall Optimizations
-  Optimizations["strcpy"] = &StrCpy;
   Optimizations["strncpy"] = &StrNCpy;
   Optimizations["stpcpy"] = &StpCpy;
   Optimizations["strlen"] = &StrLen;
@@ -1369,7 +1325,6 @@ void SimplifyLibCalls::InitOptimizations() {
   AddOpt(LibFunc::memset, &MemSet);
 
   // _chk variants of String and Memory LibCall Optimizations.
-  Optimizations["__strcpy_chk"] = &StrCpyChk;
   Optimizations["__stpcpy_chk"] = &StpCpyChk;
 
   // Math Library Optimizations
-- 
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