perf jevents: Drop or simplify small integer values

Prior to this patch '0' would be dropped as the config values default
to 0. Some json values are hex and the string '0' wouldn't match '0x0'
as zero. Add a more robust is_zero test to drop these event terms.

When encoding numbers as hex, if the number is between 0 and 9
inclusive then don't add a 0x prefix.

Update test expectations for these changes.

On x86 this reduces the event/metric C string by 58,411 bytes.

Signed-off-by: Ian Rogers <irogers@google.com>
Reviewed-by: Kan Liang <kan.liang@linux.intel.com>
Cc: Edward Baker <edward.baker@intel.com>
Cc: Perry Taylor <perry.taylor@intel.com>
Cc: Weilin Wang <weilin.wang@intel.com>
Cc: John Garry <john.g.garry@oracle.com>
Cc: Jing Zhang <renyu.zj@linux.alibaba.com>
Cc: Kajol Jain <kjain@linux.ibm.com>
Cc: Michael Petlan <mpetlan@redhat.com>
Cc: Veronika Molnarova <vmolnaro@redhat.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Link: https://lore.kernel.org/r/20240131201429.792138-1-irogers@google.com

1 files changed, 20 insertions, 3 deletions

diff --git a/tools/perf/pmu-events/jevents.py b/tools/perf/pmu-events/jevents.py
index 53ab050c8fa4..2c7e5d61ce92 100755
--- a/tools/perf/pmu-events/jevents.py
+++ b/tools/perf/pmu-events/jevents.py
@@ -203,7 +203,7 @@ class JsonEvent:
 
     def llx(x: int) -> str:
       """Convert an int to a string similar to a printf modifier of %#llx."""
-      return '0' if x == 0 else hex(x)
+      return str(x) if x >= 0 and x < 10 else hex(x)
 
     def fixdesc(s: str) -> str:
       """Fix formatting issue for the desc string."""
@@ -294,6 +294,23 @@ class JsonEvent:
       }
       return table[unit] if unit in table else f'uncore_{unit.lower()}'
 
+    def is_zero(val: str) -> bool:
+        try:
+            if val.startswith('0x'):
+                return int(val, 16) == 0
+            else:
+                return int(val) == 0
+        except e:
+            return False
+
+    def canonicalize_value(val: str) -> str:
+        try:
+            if val.startswith('0x'):
+                return llx(int(val, 16))
+            return str(int(val))
+        except e:
+            return val
+
     eventcode = 0
     if 'EventCode' in jd:
       eventcode = int(jd['EventCode'].split(',', 1)[0], 0)
@@ -358,8 +375,8 @@ class JsonEvent:
         ('RdWrMask', 'rdwrmask='),
     ]
     for key, value in event_fields:
-      if key in jd and jd[key] != '0':
-        event += ',' + value + jd[key]
+      if key in jd and not is_zero(jd[key]):
+        event += f',{value}{canonicalize_value(jd[key])}'
     if filter:
       event += f',{filter}'
     if msr: