As the third column in figure 512 shows several

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Unformatted text preview: ‘X’ to indicate such a ratio, where the factor “3.5X” is expressed verbally as “3.5 times.” The more traditional way of expressing relative change as a percentage works well when the change is small, but its definition is ambiguous. Should it be ÌÓÐ ÌÒ Û ÌÒ Û or possibly ÌÓÐ ÌÒ Û ÌÓÐ , or something else? In addition, it is less instructive for large changes. Saying that “performance improved by 250%” is more difficult to comprehend than simply saying that the performance improved by a factor of 3.5. End Aside. ½¼¼ ¡ ´ µ ½¼¼ ¡ ´ µ 5.6 Eliminating Unneeded Memory References The code for combine3 accumulates the value being computed by the combining operation at the location designated by pointer dest. This attribute can be seen by examining the assembly code generated for the compiled loop, with integers as the data type and multiplication as the combining operation. In this code, register %ecx points to data, %edx contains the value of i, and %edi points to dest. combine3: type=INT, OPER = * dest in %edi, data in %ecx, i in %edx, length in %esi .L18: loop: movl (%edi),%eax Read *dest imull (%ecx,%ed...
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