Instruction scheduling: Difference between revisions

Revision as of 00:29, 1 September 2020

Revision as of 04:05, 8 September 2020

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== Compiler examples ==

The [[GNU Compiler Collection]] is one compiler known to perform instruction scheduling, using the {{code|-march}} (both instruction set and scheduling) or {{code|-mtune}} (only scheduling) flags. It uses descriptions of instruction latencies and what instructions can be run in parallel (or equivalently, which "ALU port" each use) for each microarchitecture to perform the task. This feature is available to almost all architectures that GCC supports.<ref>{{cite web |title=x86 Options |url=https://gcc.gnu.org/onlinedocs/gcc/x86-Options.html |website=Using the GNU Compiler Collection (GCC)}}</ref>

Until version 12.0.0, the instruction scheduling in [[LLVM]]/Clang could only accept a {{code|-march}} (called {{code|target-cpu}} in LLVM parlance) switch for both instruction set and scheduling. Version 12 adds support for {{code|-mtune}} ({{code|tune-cpu}}) for x86 only.<ref>{{cite web |title=⚙ D85384 [X86] Add basic support for -mtune command line option in clang |url=http://reviews.llvm.org/D85384 |website=reviews.llvm.org}}</ref>