[PATCH] D95480: [NFC] Fix bug with parsing hybrid sample trace line

[Lei Wang via Phabricator via llvm-commits]

wlei updated this revision to Diff 319442.
wlei added a comment.

update comments


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D95480/new/

https://reviews.llvm.org/D95480

Files:
  llvm/test/tools/llvm-profgen/Inputs/inline-cs-noprobe.perfscript
  llvm/tools/llvm-profgen/PerfReader.cpp


Index: llvm/tools/llvm-profgen/PerfReader.cpp
===================================================================
--- llvm/tools/llvm-profgen/PerfReader.cpp
+++ llvm/tools/llvm-profgen/PerfReader.cpp
@@ -406,11 +406,12 @@
   ProfiledBinary *Binary = nullptr;
   while (!TraceIt.isAtEoF() && !TraceIt.getCurrentLine().startswith(" 0x")) {
     StringRef FrameStr = TraceIt.getCurrentLine().ltrim();
-    // We might get an empty line at the beginning or comments, skip it
     uint64_t FrameAddr = 0;
     if (FrameStr.getAsInteger(16, FrameAddr)) {
+      // We might parse a non-perf sample line like empty line and comments,
+      // skip it
       TraceIt.advance();
-      break;
+      return false;
     }
     TraceIt.advance();
     if (!Binary) {
@@ -437,9 +438,9 @@
     CallStack.emplace_back(FrameAddr);
   }
 
-  if (CallStack.empty())
-    return false;
   // Skip other unrelated line, find the next valid LBR line
+  // Note that even for empty call stack, we should skip the address at the
+  // bottom, otherwise the following pass may generate a truncated callstack
   while (!TraceIt.isAtEoF() && !TraceIt.getCurrentLine().startswith(" 0x")) {
     TraceIt.advance();
   }
@@ -451,7 +452,8 @@
   // of such case - when sample landed in prolog/epilog, somehow stack
   // walking will be broken in an unexpected way that higher frames will be
   // missing.
-  return !Binary->addressInPrologEpilog(CallStack.front());
+  return !CallStack.empty() &&
+         !Binary->addressInPrologEpilog(CallStack.front());
 }
 
 void PerfReader::parseHybridSample(TraceStream &TraceIt) {
Index: llvm/test/tools/llvm-profgen/Inputs/inline-cs-noprobe.perfscript
===================================================================
--- llvm/test/tools/llvm-profgen/Inputs/inline-cs-noprobe.perfscript
+++ llvm/test/tools/llvm-profgen/Inputs/inline-cs-noprobe.perfscript
@@ -1,5 +1,11 @@
 PERF_RECORD_MMAP2 2854748/2854748: [0x400000(0x1000) @ 0 00:1d 123291722 526021]: r-xp /home/inline-cs-noprobe.perfbin
 
+; test for an external or invalid top address, should skip the whole sample
+
+	        ffffffff
+	          40067e
+	5541f689495641d7
+ 0x4006c8/0x40067e/P/-/-/0  0x4006c8/0x40067e/P/-/-/0  0x4006c8/0x40067e/P/-/-/0  0x4006c8/0x40067e/P/-/-/0  0x4006c8/0x40067e/P/-/-/0  0x4006c8/0x40067e/P/-/-/0  0x4006c8/0x40067e/P/-/-/0  0x4006c8/0x40067e/P/-/-/0  0x4006c8/0x40067e/P/-/-/0  0x4006c8/0x40067e/P/-/-/0  0x4006c8/0x40067e/P/-/-/0  0x4006c8/0x40067e/P/-/-/0  0x40069b/0x400670/M/-/-/0  0x4006c8/0x40067e/P/-/-/0  0x4006c8/0x40067e/P/-/-/0  0x4006c8/0x40067e/P/-/-/0
 
 	          40067e
 	5541f689495641d7


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