Common subexpression elimination

The removal of common subexpressions (English common subexpression elimination ) describes a compiler optimization. It is this search for subexpressions that have previously been computed. If these are found, the previous result is stored in a variable and the repeated calculation replaced by the variable.

Example

The following program section, the value of a * b * is calculated twice,

X = a * b c; y = a * b d; The CSE transforms the section then so that the first result is cached:

_tmp = a * b; x = _tmp c; y = _tmp d; References

  • Compiler
  • Compiler optimization
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