The BHT offers significant branch performance benefits. The BHT allows each PU to take instruction branches that are based on a stored BHT, which improves processing times for calculation routines. In addition to the BHT, z14 servers use the following techniques to improve the prediction of the correct branch to be run: 

GLYPH<SM590000> BTB 

GLYPH<SM590000> PHT 

GLYPH<SM590000> BTB data compression 

The success rate of branch prediction contributes significantly to the superscalar aspects of z14 servers. This success is because the architecture rules prescribe that, for successful parallel execution of an instruction stream, the correctly predicted result of the branch is essential. 

The z14 branch prediction includes the following enhancements over z13: 

GLYPH<SM590000> Branch prediction search pipeline extended from five to six cycles to accommodate new predictors for increased accuracy/performance. 

GLYPH<SM590000> New predictors: 

GLYPH<SM590000> Capacity increases: 

GLYPH<SM590000> Better power efficiency: Several structures were redesigned to maintain their accuracy while less power is used through smart access algorithms. 

GLYPH<SM590000> New static IBM IAfi regions expanded from four to eight. To conserve space, prediction structures do not store full target addresses. Instead, they use the locality and limited ranges of “4gig regions” of virtual instruction addresses - IA(0:31). 

## 3.4.10 Wild branch 

When a bad pointer is used or when code overlays a data area that contains a pointer to code, a random branch is the result. This process causes a 0C1 or 0C4 abend. Random branches are difficult to diagnose because clues about how the system got there are not evident. 

With the wild branch hardware facility, the last address from which a successful branch instruction was run is kept. z/OS uses this information with debugging aids, such as the SLIP command, to determine from where a wild branch came. It can also collect data from that storage location. This approach decreases the number of debugging steps that are necessary when you want to know from where the branch came. 

