[llvm-commits] [llvm] r61297 - in /llvm/trunk: lib/Transforms/Scalar/SimplifyLibCalls.cpp test/Transforms/SimplifyLibCalls/2008-12-20-StrcmpMemcmp.ll

[Devang Patel]

Nick,

	char *s1 = "hi\0how are you";
	char *s2 = "hi\0I am fine  ";

s1 and s2 are identical as per strcmp, but memcmp does not agree. Do  
you handle this case ?
-
Devang

On Dec 20, 2008, at 4:19 PM, Nick Lewycky wrote:

> Author: nicholas
> Date: Sat Dec 20 18:19:21 2008
> New Revision: 61297
>
> URL: http://llvm.org/viewvc/llvm-project?rev=61297&view=rev
> Log:
> Turn strcmp into memcmp, such as strcmp(P, "x") --> memcmp(P, "x", 2).
>
> Added:
>    llvm/trunk/test/Transforms/SimplifyLibCalls/2008-12-20- 
> StrcmpMemcmp.ll
> Modified:
>    llvm/trunk/lib/Transforms/Scalar/SimplifyLibCalls.cpp
>
> Modified: llvm/trunk/lib/Transforms/Scalar/SimplifyLibCalls.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/SimplifyLibCalls.cpp?rev=61297&r1=61296&r2=61297&view=diff
>
> = 
> = 
> = 
> = 
> = 
> = 
> = 
> = 
> ======================================================================
> --- llvm/trunk/lib/Transforms/Scalar/SimplifyLibCalls.cpp (original)
> +++ llvm/trunk/lib/Transforms/Scalar/SimplifyLibCalls.cpp Sat Dec 20  
> 18:19:21 2008
> @@ -80,7 +80,10 @@
>   /// EmitMemChr - Emit a call to the memchr function.  This assumes  
> that Ptr is
>   /// a pointer, Val is an i32 value, and Len is an 'intptr_t' value.
>   Value *EmitMemChr(Value *Ptr, Value *Val, Value *Len, IRBuilder<>  
> &B);
> -
> +
> +  /// EmitMemCmp - Emit a call to the memcmp function.
> +  Value *EmitMemCmp(Value *Ptr1, Value *Ptr2, Value *Len,  
> IRBuilder<> &B);
> +
>   /// EmitUnaryFloatFnCall - Emit a call to the unary function named  
> 'Name' (e.g.
>   /// 'floor').  This function is known to take a single of type  
> matching 'Op'
>   /// and returns one value with the same type.  If 'Op' is a long  
> double, 'l'
> @@ -106,7 +109,7 @@
>   /// EmitFWrite - Emit a call to the fwrite function.  This assumes  
> that Ptr is
>   /// a pointer, Size is an 'intptr_t', and File is a pointer to FILE.
>   void EmitFWrite(Value *Ptr, Value *Size, Value *File, IRBuilder<>  
> &B);
> -
> +
> };
> } // End anonymous namespace.
>
> @@ -151,6 +154,19 @@
>   return B.CreateCall3(MemChr, CastToCStr(Ptr, B), Val, Len,  
> "memchr");
> }
>
> +/// EmitMemCmp - Emit a call to the memcmp function.
> +Value *LibCallOptimization::EmitMemCmp(Value *Ptr1, Value *Ptr2,
> +                                       Value *Len, IRBuilder<> &B) {
> +  Module *M = Caller->getParent();
> +  Value *MemCmp = M->getOrInsertFunction("memcmp",
> +                                         Type::Int32Ty,
> +                                          
> PointerType::getUnqual(Type::Int8Ty),
> +                                          
> PointerType::getUnqual(Type::Int8Ty),
> +                                         TD->getIntPtrType(), NULL);
> +  return B.CreateCall3(MemCmp, CastToCStr(Ptr1, B),  
> CastToCStr(Ptr2, B),
> +                       Len, "memcmp");
> +}
> +
> /// EmitUnaryFloatFnCall - Emit a call to the unary function named  
> 'Name' (e.g.
> /// 'floor').  This function is known to take a single of type  
> matching 'Op' and
> /// returns one value with the same type.  If 'Op' is a long double,  
> 'l' is
> @@ -537,6 +553,18 @@
>     // strcmp(x, y)  -> cnst  (if both x and y are constant strings)
>     if (HasStr1 && HasStr2)
>       return ConstantInt::get(CI->getType(),  
> strcmp(Str1.c_str(),Str2.c_str()));
> +
> +    // strcmp(P, "x") -> memcmp(P, "x", 2)
> +    uint64_t Len1 = GetStringLength(Str1P);
> +    uint64_t Len2 = GetStringLength(Str2P);
> +    if (Len1 || Len2) {
> +      // Choose the smallest Len excluding 0 which means 'unknown'.
> +      if (!Len1 || (Len2 && Len2 < Len1))
> +        Len1 = Len2;
> +      return EmitMemCmp(Str1P, Str2P,
> +                        ConstantInt::get(TD->getIntPtrType(),  
> Len1), B);
> +    }
> +
>     return 0;
>   }
> };
>
> Added: llvm/trunk/test/Transforms/SimplifyLibCalls/2008-12-20- 
> StrcmpMemcmp.ll
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/SimplifyLibCalls/2008-12-20-StrcmpMemcmp.ll?rev=61297&view=auto
>
> = 
> = 
> = 
> = 
> = 
> = 
> = 
> = 
> ======================================================================
> --- llvm/trunk/test/Transforms/SimplifyLibCalls/2008-12-20- 
> StrcmpMemcmp.ll (added)
> +++ llvm/trunk/test/Transforms/SimplifyLibCalls/2008-12-20- 
> StrcmpMemcmp.ll Sat Dec 20 18:19:21 2008
> @@ -0,0 +1,10 @@
> +; RUN: llvm-as < %s | opt -simplify-libcalls | llvm-dis | grep  
> call.*memcmp
> +
> + at .str = internal constant [2 x i8] c"x\00"
> +
> +declare i32 @strcmp(i8* %dest, i8* %src)
> +
> +define i32 @foo(i8* %x, i8* %y) {
> +  %A = call i32 @strcmp(i8* %x, i8* getelementptr ([2 x i8]* @.str,  
> i32 0, i32 0))
> +  ret i32 %A
> +}
>
>
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