[llvm-commits] [llvm] r51240 - in /llvm/trunk: lib/Transforms/Scalar/SimplifyLibCalls.cpp test/Transforms/SimplifyLibCalls/2008-05-19-memcmp.ll

[Chris Lattner]

Whoa, thanks Duncan!  (and Scott for tracking it down!)

-Chris

On May 19, 2008, at 2:27 AM, Duncan Sands wrote:

> Author: baldrick
> Date: Mon May 19 04:27:24 2008
> New Revision: 51240
>
> URL: http://llvm.org/viewvc/llvm-project?rev=51240&view=rev
> Log:
> Fix PR2341 - when the length is 4 use an i32 not
> an i16!  Cleaned up trailing whitespace while there.
>
> Added:
>    llvm/trunk/test/Transforms/SimplifyLibCalls/2008-05-19-memcmp.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=51240&r1=51239&r2=51240&view=diff
>
> =
> =
> =
> =
> =
> =
> =
> =
> ======================================================================
> --- llvm/trunk/lib/Transforms/Scalar/SimplifyLibCalls.cpp (original)
> +++ llvm/trunk/lib/Transforms/Scalar/SimplifyLibCalls.cpp Mon May 19  
> 04:27:24 2008
> @@ -731,17 +731,17 @@
>         !isa<PointerType>(FT->getParamType(1)) ||
>         FT->getReturnType() != Type::Int32Ty)
>       return 0;
> -
> +
>     Value *LHS = CI->getOperand(1), *RHS = CI->getOperand(2);
> -
> +
>     if (LHS == RHS)  // memcmp(s,s,x) -> 0
>       return Constant::getNullValue(CI->getType());
> -
> +
>     // Make sure we have a constant length.
>     ConstantInt *LenC = dyn_cast<ConstantInt>(CI->getOperand(3));
>     if (!LenC) return 0;
>     uint64_t Len = LenC->getZExtValue();
> -
> +
>     if (Len == 0) // memcmp(s1,s2,0) -> 0
>       return Constant::getNullValue(CI->getType());
>
> @@ -750,18 +750,20 @@
>       Value *RHSV = B.CreateLoad(CastToCStr(RHS, B), "rhsv");
>       return B.CreateZExt(B.CreateSub(LHSV, RHSV, "chardiff"), CI- 
> >getType());
>     }
> -
> +
>     // memcmp(S1,S2,2) != 0 -> (*(short*)LHS ^ *(short*)RHS)  != 0
>     // memcmp(S1,S2,4) != 0 -> (*(int*)LHS ^ *(int*)RHS)  != 0
>     if ((Len == 2 || Len == 4) &&  
> IsOnlyUsedInZeroEqualityComparison(CI)) {
> -      LHS = B.CreateBitCast(LHS,  
> PointerType::getUnqual(Type::Int16Ty), "tmp");
> -      RHS = B.CreateBitCast(RHS, LHS->getType(), "tmp");
> +      const Type *PTy = PointerType::getUnqual(Len == 2 ?
> +                                               Type::Int16Ty :  
> Type::Int32Ty);
> +      LHS = B.CreateBitCast(LHS, PTy, "tmp");
> +      RHS = B.CreateBitCast(RHS, PTy, "tmp");
>       LoadInst *LHSV = B.CreateLoad(LHS, "lhsv");
>       LoadInst *RHSV = B.CreateLoad(RHS, "rhsv");
>       LHSV->setAlignment(1); RHSV->setAlignment(1);  // Unaligned  
> loads.
>       return B.CreateZExt(B.CreateXor(LHSV, RHSV, "shortdiff"), CI- 
> >getType());
>     }
> -
> +
>     return 0;
>   }
> };
>
> Added: llvm/trunk/test/Transforms/SimplifyLibCalls/2008-05-19- 
> memcmp.ll
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/SimplifyLibCalls/2008-05-19-memcmp.ll?rev=51240&view=auto
>
> = 
> = 
> = 
> = 
> = 
> = 
> = 
> = 
> ======================================================================
> --- llvm/trunk/test/Transforms/SimplifyLibCalls/2008-05-19-memcmp.ll  
> (added)
> +++ llvm/trunk/test/Transforms/SimplifyLibCalls/2008-05-19-memcmp.ll  
> Mon May 19 04:27:24 2008
> @@ -0,0 +1,14 @@
> +; RUN: llvm-as < %s | opt -simplify-libcalls | llvm-dis | grep i32
> +; PR2341
> +
> + at _2E_str = external constant [5 x i8]		; <[5 x i8]*> [#uses=1]
> +
> +declare i32 @memcmp(i8*, i8*, i32) nounwind readonly
> +
> +define i1 @f(i8** %start_addr) {
> +entry:
> +	%tmp4 = load i8** %start_addr, align 4		; <i8*> [#uses=1]
> +	%tmp5 = call i32 @memcmp( i8* %tmp4, i8* getelementptr ([5 x i8]*  
> @_2E_str, i32 0, i32 0), i32 4 ) nounwind readonly 		; <i32> [#uses=1]
> +	%tmp6 = icmp eq i32 %tmp5, 0		; <i1> [#uses=1]
> +	ret i1 %tmp6
> +}
>
>
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