llvm-project/llvm/test/tools/llvm-exegesis
Clement Courbet 9431b72ce9 [llvm-exegesis] Add loop mode for repeating the snippet.
Summary:
Before this change the Executable function was made by duplicating the
snippet. This change adds a --repetion-mode={loop|duplicate} flag that
allows choosing between this behaviour and wrapping the snippet instructions
in a loop.

The new mode can help measurements when the snippet fits in the DSB by
short-cirtcuiting decoding. The loop adds a dec + jmp to the measurements, but
since these are not part of the critical path, they execute in parallel
with the measured code and do not impact measurements in practice.

Overview of the change:
 - New SnippetRepetitor abstraction that handles repeating the snippet.
   The assembler delegates repeating the instructions to this class.
 - ExegesisTarget learns how to decrement loop counter and jump.
 - Some refactoring of the assembler into FunctionFiller/BasicBlockFiller.

Reviewers: gchatelet

Subscribers: mgorny, tschuett, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D68125

llvm-svn: 373083
2019-09-27 12:56:24 +00:00
..
AArch64 [llvm-exegesis] Fix function return generation so it doesn't return register 0 2018-10-10 13:03:23 +00:00
X86 [llvm-exegesis] Add loop mode for repeating the snippet. 2019-09-27 12:56:24 +00:00
lit.local.cfg [llvm-exegesis] Add lit tests (v2). 2018-09-25 13:59:35 +00:00