[llvm] [XRay][account] add account test for nonempty exit mismatch (PR #93564)

[Tomer Shafir via llvm-commits]

https://github.com/tomershafir updated https://github.com/llvm/llvm-project/pull/93564

>From 3ca95eef2bc53a48f270e6e4f4ef21db54754698 Mon Sep 17 00:00:00 2001
From: tomershafir <tomer.shafir8 at gmail.com>
Date: Tue, 28 May 2024 18:21:00 +0300
Subject: [PATCH] [compiler-rt][XRay]: add account test for nonempty exit
 mismatch

---
 ...ount-exit-mismatch-empty-stack-error.yaml} |  0
 ...t-exit-mismatch-non-empty-stack-error.yaml | 31 +++++++++++++++++++
 .../llvm-xray/X86/account-keep-going.yaml     |  4 +--
 llvm/tools/llvm-xray/xray-account.cpp         |  3 ++
 4 files changed, 36 insertions(+), 2 deletions(-)
 rename llvm/test/tools/llvm-xray/X86/{account-empty-stack-error.yaml => account-exit-mismatch-empty-stack-error.yaml} (100%)
 create mode 100644 llvm/test/tools/llvm-xray/X86/account-exit-mismatch-non-empty-stack-error.yaml

diff --git a/llvm/test/tools/llvm-xray/X86/account-empty-stack-error.yaml b/llvm/test/tools/llvm-xray/X86/account-exit-mismatch-empty-stack-error.yaml
similarity index 100%
rename from llvm/test/tools/llvm-xray/X86/account-empty-stack-error.yaml
rename to llvm/test/tools/llvm-xray/X86/account-exit-mismatch-empty-stack-error.yaml
diff --git a/llvm/test/tools/llvm-xray/X86/account-exit-mismatch-non-empty-stack-error.yaml b/llvm/test/tools/llvm-xray/X86/account-exit-mismatch-non-empty-stack-error.yaml
new file mode 100644
index 0000000000000..149bf5e1b77ed
--- /dev/null
+++ b/llvm/test/tools/llvm-xray/X86/account-exit-mismatch-non-empty-stack-error.yaml
@@ -0,0 +1,31 @@
+#RUN: not llvm-xray account %s -o - -m %S/Inputs/simple-instrmap.yaml -d 2>&1 | FileCheck %s
+#RUN: llvm-xray account %s -k -o - -m %S/Inputs/simple-instrmap.yaml -d 2>&1 | FileCheck %s --check-prefix=KEEPGOING
+
+---
+header:
+  version: 1
+  type: 0
+  constant-tsc: true
+  nonstop-tsc: true
+  cycle-frequency: 0
+records:
+# An exit record doesn't match an entry record on a non empty stack with sibling call deduction. 
+# This can happen for example when an instrumented function does a 'fork()', 
+# where the child process will not see
+# the entry record but see the exit record. This is completely valid data,
+# which should be handled with grace (i.e. we treat it as an error, but since
+# the llvm-xray account tool has an option to keep going, gives the user a
+# chance to retry).
+  - { type: 0, func-id: 1, cpu: 1, thread: 1, kind: function-enter, tsc: 10000 }
+  - { type: 0, func-id: 4, cpu: 1, thread: 1, kind: function-exit,  tsc: 10001 }
+  - { type: 0, func-id: 1, cpu: 1, thread: 1, kind: function-exit,  tsc: 10002 }
+...
+
+#CHECK:      Error processing record: {{.*}}
+#CHECK-NEXT: Thread ID: 1\n
+#CHECK-NEXT: #1 @(1)\n
+#CHECK-NEXT: llvm-xray: Failed accounting function calls in file '{{.*}}'.
+
+#KEEPGOING:      Error processing record: {{.*}}
+#KEEPGOING-NEXT: Thread ID: 1\n
+#KEEPGOING-NEXT: #1 @(1)\n
diff --git a/llvm/test/tools/llvm-xray/X86/account-keep-going.yaml b/llvm/test/tools/llvm-xray/X86/account-keep-going.yaml
index 76011ee8e6e5e..fb1a8f422bad7 100644
--- a/llvm/test/tools/llvm-xray/X86/account-keep-going.yaml
+++ b/llvm/test/tools/llvm-xray/X86/account-keep-going.yaml
@@ -7,8 +7,8 @@ header:
   nonstop-tsc: true
   cycle-frequency: 0
 records:
-# We want to test the case for when we see spurious exits, but keep going
-# anyway ignoring the records in the process.
+# We want to test the case for when we see spurious exits without sibling call deduction, 
+# but keep going anyway ignoring the records in the process.
   - { type: 0, func-id: 1, cpu: 1, thread: 111, kind: function-enter, tsc: 10000 }
   - { type: 0, func-id: 2, cpu: 1, thread: 111, kind: function-enter, tsc: 10001 }
   - { type: 0, func-id: 3, cpu: 1, thread: 111, kind: function-enter, tsc: 10002 }
diff --git a/llvm/tools/llvm-xray/xray-account.cpp b/llvm/tools/llvm-xray/xray-account.cpp
index 24a3552cfb91e..d3380ad8820ad 100644
--- a/llvm/tools/llvm-xray/xray-account.cpp
+++ b/llvm/tools/llvm-xray/xray-account.cpp
@@ -198,6 +198,7 @@ bool LatencyAccountant::accountRecord(const XRayRecord &Record) {
       break;
     }
 
+    // A sibling call, need to be deduced
     if (!DeduceSiblingCalls)
       return false;
 
@@ -207,6 +208,8 @@ bool LatencyAccountant::accountRecord(const XRayRecord &Record) {
                       [&](const std::pair<const int32_t, uint64_t> &E) {
                         return E.first == Record.FuncId;
                       });
+    // Gracefully return when an exit doesn't match any entry on a non empty stack, 
+    // e.g. it can happen on a fork()
     if (Parent == ThreadStack.Stack.rend())
       return false;