[llvm] e696f4e - [llvm-exegesis] Fix LBR checks/test

[Aiden Grossman via llvm-commits]

Author: Aiden Grossman
Date: 2025-03-25T08:10:58Z
New Revision: e696f4e5008c21b8edee089fb80d4e2e0d998e20

URL: https://github.com/llvm/llvm-project/commit/e696f4e5008c21b8edee089fb80d4e2e0d998e20
DIFF: https://github.com/llvm/llvm-project/commit/e696f4e5008c21b8edee089fb80d4e2e0d998e20.diff

LOG: [llvm-exegesis] Fix LBR checks/test

This patch fixes the LBR check in the local lit config. The test would
segfault as the loop body would be basically empty, causing a divide by
zero error. More investigation is needed there so we do not actually hit
that assertion and report a cleaner error somewhere. Specifying an
actual opcode to benchmark fixes the problem. The test would also fail
as -mcpu was set to the default x86 CPU rather than the one currently
being run on, so it would always fail to find a perf counter. This patch
fixes that by simply removing the -mcpu flag.

Given these issues, I'm not sure these tests have ever run in the ~5
years they have been in tree. There were some issues reported in
\#132861, so I guess we'll see if there are further issues when the
testing becomes more broad.

Added: 
    

Modified: 
    llvm/test/tools/llvm-exegesis/X86/lbr/mov-add.s
    llvm/test/tools/llvm-exegesis/lit.local.cfg

Removed: 
    


################################################################################
diff  --git a/llvm/test/tools/llvm-exegesis/X86/lbr/mov-add.s b/llvm/test/tools/llvm-exegesis/X86/lbr/mov-add.s
index 2a8cc8e34450a..250c297367791 100644
--- a/llvm/test/tools/llvm-exegesis/X86/lbr/mov-add.s
+++ b/llvm/test/tools/llvm-exegesis/X86/lbr/mov-add.s
@@ -1,4 +1,4 @@
-# RUN: llvm-exegesis -mtriple=x86_64-unknown-unknown -mcpu=x86-64 -mode=latency --repetition-mode=loop --x86-lbr-sample-period=521 --snippets-file=%p/Inputs/mov_add.att
+# RUN: llvm-exegesis -mtriple=x86_64-unknown-unknown -mode=latency --repetition-mode=loop --x86-lbr-sample-period=521 --snippets-file=%p/Inputs/mov_add.att
 # REQUIRES: exegesis-can-execute-x86_64, exegesis-can-measure-latency-lbr
 
 

diff  --git a/llvm/test/tools/llvm-exegesis/lit.local.cfg b/llvm/test/tools/llvm-exegesis/lit.local.cfg
index a51a2d73442fa..89110ed2816cd 100644
--- a/llvm/test/tools/llvm-exegesis/lit.local.cfg
+++ b/llvm/test/tools/llvm-exegesis/lit.local.cfg
@@ -20,7 +20,7 @@ def can_use_perf_counters(mode, extra_options=[]):
         return False
     try:
         return_code = subprocess.call(
-            [llvm_exegesis_exe, "-mode", mode, "-snippets-file", "/dev/null"]
+            [llvm_exegesis_exe, "-mode", mode, "-opcode-name=ADD64rr"]
             + extra_options,
             stdout=subprocess.DEVNULL,
             stderr=subprocess.DEVNULL,