A portable global optimizer and linker
PLDI '88 Proceedings of the ACM SIGPLAN 1988 conference on Programming Language design and Implementation
Eliminating branches using a superoptimizer and the GNU C compiler
PLDI '92 Proceedings of the ACM SIGPLAN 1992 conference on Programming language design and implementation
PLDI '93 Proceedings of the ACM SIGPLAN 1993 conference on Programming language design and implementation
Avoiding conditional branches by code replication
PLDI '95 Proceedings of the ACM SIGPLAN 1995 conference on Programming language design and implementation
Critical path reduction for scalar programs
Proceedings of the 28th annual international symposium on Microarchitecture
Interprocedural conditional branch elimination
Proceedings of the ACM SIGPLAN 1997 conference on Programming language design and implementation
Improving performance by branch reordering
PLDI '98 Proceedings of the ACM SIGPLAN 1998 conference on Programming language design and implementation
Computer architecture (2nd ed.): a quantitative approach
Computer architecture (2nd ed.): a quantitative approach
Control CPR: a branch height reduction optimization for EPIC architectures
Proceedings of the ACM SIGPLAN 1999 conference on Programming language design and implementation
Dynamo: a transparent dynamic optimization system
PLDI '00 Proceedings of the ACM SIGPLAN 2000 conference on Programming language design and implementation
ACM Computing Surveys (CSUR)
Conjunctive selection conditions in main memory
Proceedings of the twenty-first ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
A Retargetable C Compiler: Design and Implementation
A Retargetable C Compiler: Design and Implementation
Efficient and effective branch reordering using profile data
ACM Transactions on Programming Languages and Systems (TOPLAS)
Coalescing Conditional Branches into Efficient Indirect Jumps
SAS '97 Proceedings of the 4th International Symposium on Static Analysis
| Hi-index | 0.00 |
Conditional branches are expensive. Branches require a significant percentage of execution cycles since they occur frequently and cause pipeline flushes when mispredicted. In addition, branches result in forks in the control flow, which can prevent other code-improving transformations from being applied. In this paper we describe profile-based techniques for replacing the execution of a set of two or more branches with a single branch on a conventional scalar processor. These sets of branches can include tests of multiple variables. For instance, the test if (p1 ! = 0 && p2 ! = 0), which is testing for NULL pointers, can be replaced with if (p1 & p2 ! = 0). Program profiling is performed to target condition merging along frequently executed paths. The results show that eliminating branches by merging conditions can significantly reduce the number of conditional branches executed in non-numerical applications.