Chapter 5.11, Problem 5.9PP

Program Plan Intro

Given C code:

void merge(long src1[], long src2[], long dest[], long n)

{

long i1 = 0;

long i2 = 0;

long id = 0;

while(i1<n && i2<n)

{

if(src1[i1]<src2[i2])

dest[id++] = src1[i1++];

else

dest[id++] = src2[i2++];

}

while(i1<n)

dest[id++] = src1[i1++];

while(i2<n)

dest[id++] = src2[i2++];

}

Cycles per element (CPE):

• The CPE denotes performance of program that helps in improving code.
• It helps to understand detailed level loop performance for an iterative program.
• It is appropriate for programs that use a repetitive computation.
• The processor’s activity sequencing is controlled by a clock that provides regular signal of some frequency.

Memory aliasing:

• It denotes a case where two pointers might designate to memory location that is same.
• The compiler should assume that unlike pointers might be aliased for safe optimizations.
• The program aspects that could limit chances for a compiler in generating optimized code denote optimization blockers.
• If a compiler is unable to determine whether two pointers might be aliased, it should adopt that either case would be possible.
• The possible optimization set is been limited in this case.