Revert [InstCombine] sprintf(dest, "%s", str) -> memccpy(dest, str, 0, MAX)

Seems to be slower than memcpy + strlen.

llvm-svn: 373335

1 files changed, 12 insertions, 29 deletions

diff --git a/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp b/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp
index c77daba4a95..3af754a3eb0 100644
--- a/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp
+++ b/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp
@@ -2415,11 +2415,9 @@ Value *LibCallSimplifier::optimizePrintF(CallInst *CI, IRBuilder<> &B) {
 }
 
 Value *LibCallSimplifier::optimizeSPrintFString(CallInst *CI, IRBuilder<> &B) {
-  Value *Dst = CI->getArgOperand(0);
-  Value *FmtStr = CI->getArgOperand(1);
   // Check for a fixed format string.
   StringRef FormatStr;
-  if (!getConstantStringInfo(FmtStr, FormatStr))
+  if (!getConstantStringInfo(CI->getArgOperand(1), FormatStr))
     return nullptr;
 
   // If we just have a format string (nothing else crazy) transform it.
@@ -2430,10 +2428,9 @@ Value *LibCallSimplifier::optimizeSPrintFString(CallInst *CI, IRBuilder<> &B) {
       return nullptr; // we found a format specifier, bail out.
 
     // sprintf(str, fmt) -> llvm.memcpy(align 1 str, align 1 fmt, strlen(fmt)+1)
-    B.CreateMemCpy(
-        Dst, 1, FmtStr, 1,
-        ConstantInt::get(DL.getIntPtrType(CI->getContext()),
-                         FormatStr.size() + 1)); // Copy the null byte.
+    B.CreateMemCpy(CI->getArgOperand(0), 1, CI->getArgOperand(1), 1,
+                   ConstantInt::get(DL.getIntPtrType(CI->getContext()),
+                                    FormatStr.size() + 1)); // Copy the null byte.
     return ConstantInt::get(CI->getType(), FormatStr.size());
   }
 
@@ -2443,14 +2440,13 @@ Value *LibCallSimplifier::optimizeSPrintFString(CallInst *CI, IRBuilder<> &B) {
       CI->getNumArgOperands() < 3)
     return nullptr;
 
-  Value *Str = CI->getArgOperand(2);
   // Decode the second character of the format string.
   if (FormatStr[1] == 'c') {
     // sprintf(dst, "%c", chr) --> *(i8*)dst = chr; *((i8*)dst+1) = 0
-    if (!Str->getType()->isIntegerTy())
+    if (!CI->getArgOperand(2)->getType()->isIntegerTy())
       return nullptr;
-    Value *V = B.CreateTrunc(Str, B.getInt8Ty(), "char");
-    Value *Ptr = castToCStr(Dst, B);
+    Value *V = B.CreateTrunc(CI->getArgOperand(2), B.getInt8Ty(), "char");
+    Value *Ptr = castToCStr(CI->getArgOperand(0), B);
     B.CreateStore(V, Ptr);
     Ptr = B.CreateGEP(B.getInt8Ty(), Ptr, B.getInt32(1), "nul");
     B.CreateStore(B.getInt8(0), Ptr);
@@ -2459,30 +2455,17 @@ Value *LibCallSimplifier::optimizeSPrintFString(CallInst *CI, IRBuilder<> &B) {
   }
 
   if (FormatStr[1] == 's') {
-    if (!Str->getType()->isPointerTy())
-      return nullptr;
-  
-    // sprintf(dest, "%s", str) -> memccpy(dest, str, 0, MAX)
-    if (CI->use_empty()) {
-      Value *S = (Dst->getType() == Str->getType())
-                     ? Str
-                     : B.CreateBitCast(Str, Dst->getType());
-      unsigned SizeTyBitwidth =
-          DL.getIntPtrType(CI->getContext())->getPrimitiveSizeInBits();
-      Value *NewSize = ConstantInt::get(B.getIntNTy(SizeTyBitwidth),
-                                        APInt::getMaxValue(SizeTyBitwidth));
-      emitMemCCpy(Dst, S, B.getInt32('\0'), NewSize, B, TLI);
-      return Dst;
-    }
-
     // sprintf(dest, "%s", str) -> llvm.memcpy(align 1 dest, align 1 str,
     // strlen(str)+1)
-    Value *Len = emitStrLen(Str, B, DL, TLI);
+    if (!CI->getArgOperand(2)->getType()->isPointerTy())
+      return nullptr;
+
+    Value *Len = emitStrLen(CI->getArgOperand(2), B, DL, TLI);
     if (!Len)
       return nullptr;
     Value *IncLen =
         B.CreateAdd(Len, ConstantInt::get(Len->getType(), 1), "leninc");
-    B.CreateMemCpy(Dst, 1, Str, 1, IncLen);
+    B.CreateMemCpy(CI->getArgOperand(0), 1, CI->getArgOperand(2), 1, IncLen);
 
     // The sprintf result is the unincremented number of bytes in the string.
     return B.CreateIntCast(Len, CI->getType(), false);