[PATCH] D117788: [llvm-mca] Improve barriers for strict region marking (PR52198)
Simon Pilgrim via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Thu Jan 20 07:36:02 PST 2022
RKSimon created this revision.
RKSimon added reviewers: andreadb, lebedev.ri.
Herald added a subscriber: gbedwell.
RKSimon requested review of this revision.
Herald added a project: LLVM.
As suggested on the bug, to help (but not completely....) stop folded instructions crossing the inline asm barriers used for llvm-mca analysis, we should recommend tagging with memory captures/attributes.
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D117788
Files:
llvm/docs/CommandGuide/llvm-mca.rst
Index: llvm/docs/CommandGuide/llvm-mca.rst
===================================================================
--- llvm/docs/CommandGuide/llvm-mca.rst
+++ llvm/docs/CommandGuide/llvm-mca.rst
@@ -299,9 +299,9 @@
.. code-block:: c++
int foo(int a, int b) {
- __asm volatile("# LLVM-MCA-BEGIN foo");
+ __asm volatile("# LLVM-MCA-BEGIN foo":::"memory");
a += 42;
- __asm volatile("# LLVM-MCA-END");
+ __asm volatile("# LLVM-MCA-END":::"memory");
a *= b;
return a;
}
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