[PATCH v2] perf script: Update brstack syntax documentation

[Yujie Liu <yujie.liu@intel.com>]

The following commits added new fields/flags to the branch stack field
list:

commit 1f48989cdc7d ("perf script: Output branch sample type")
commit 6ade6c646035 ("perf script: Show branch speculation info")
commit 1e66dcff7b9b ("perf script: Add not taken event for branch stack")

Update brstack syntax documentation to be consistent with the latest
branch stack field list. Improve the descriptions to help users
interpret the fields accurately.

Signed-off-by: Yujie Liu <yujie.liu@intel.com>
---
Changes in v2:
- Add not taken event (Namhyung, Leo)
- Change field name from PRED to EVENT for generic use and furture
  extension (Leo)

v1: https://lore.kernel.org/all/20250225061736.1698175-1-yujie.liu@intel.com/
---
 tools/perf/Documentation/perf-script.txt | 23 ++++++++++++++++-------
 1 file changed, 16 insertions(+), 7 deletions(-)

diff --git a/tools/perf/Documentation/perf-script.txt b/tools/perf/Documentation/perf-script.txt
index b72866ef270b..28bec7e78bc8 100644
--- a/tools/perf/Documentation/perf-script.txt
+++ b/tools/perf/Documentation/perf-script.txt
@@ -239,13 +239,22 @@ OPTIONS
 	i.e., -F "" is not allowed.
 
 	The brstack output includes branch related information with raw addresses using the
-	/v/v/v/v/cycles syntax in the following order:
-	FROM: branch source instruction
-	TO  : branch target instruction
-        M/P/-: M=branch target mispredicted or branch direction was mispredicted, P=target predicted or direction predicted, -=not supported
-	X/- : X=branch inside a transactional region, -=not in transaction region or not supported
-	A/- : A=TSX abort entry, -=not aborted region or not supported
-	cycles
+	FROM/TO/EVENT/INTX/ABORT/CYCLES/TYPE/SPEC syntax in the following order:
+	FROM  : branch source instruction
+	TO    : branch target instruction
+	EVENT : M=branch target or direction was mispredicted
+	        P=branch target or direction was predicted
+	        N=branch not-taken
+	        -=no event or not supported
+	INTX  : X=branch inside a transactional region
+	        -=branch not in transaction region or not supported
+	ABORT : A=TSX abort entry
+	        -=not aborted region or not supported
+	CYCLES: the number of cycles that have elapsed since the last branch was recorded
+	TYPE  : branch type: COND/UNCOND/IND/CALL/IND_CALL/RET etc.
+	        -=not supported
+	SPEC  : branch speculation info: SPEC_WRONG_PATH/NON_SPEC_CORRECT_PATH/SPEC_CORRECT_PATH
+	        -=not supported
 
 	The brstacksym is identical to brstack, except that the FROM and TO addresses are printed in a symbolic form if possible.
 

base-commit: b10f74308e1305275e69ddde711ec817cc69e306
-- 
2.34.1