strrchr non-optimization

; ModuleID = 'str_test.c'
target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
target triple = "x86_64-apple-macosx10.9.0"

@.str = private unnamed_addr constant [12 x i8] c"some/file.c\00", align 1
@.str1 = private unnamed_addr constant [4 x i8] c"%s\0A\00", align 1

define i32 @main() nounwind ssp uwtable {
  %1 = alloca i32, align 4
  %THIS_FILE_NAME = alloca i8*, align 8
  store i32 0, i32* %1
  %2 = call i8* @strrchr(i8* getelementptr inbounds ([12 x i8]* @.str, i32 0, i32 0), i32 47)
  %3 = getelementptr inbounds i8* %2, i64 1
  store i8* %3, i8** %THIS_FILE_NAME, align 8
  %4 = load i8** %THIS_FILE_NAME, align 8
  %5 = call i32 (i8*, ...)* @printf(i8* getelementptr inbounds ([4 x i8]* @.str1, i32 0, i32 0), i8* %4)
  ret i32 0
}

declare i8* @strrchr(i8*, i32)

declare i32 @printf(i8*, ...)