[memprof] Update the frame is inline logic and unittests.

[snehasish]

Summary

Since DI frames are enumerated with the leaf function at index 0, this
patch fixes the logic when IsInlineFrame is set. Also update the
unittests to check that only the last frame is marked as non-inline from
a set of DI Frames for a PC address.

[tejohnson]

lgtm

Unfortunately the ordering is not documented on the DIInliningInfo class. And confusingly, one piece of code sets an Inlined flag by the check "I > 0" (https://github.com/llvm/llvm-project/blob/49c048add4c980936fc2918838288ae2d795587d/llvm/lib/DebugInfo/Symbolize/DIPrinter.cpp#L198).
However, if I look at how that flag is used, it is used to print "(inlined by)" *before* the current frame's function name, so it seems to apply to the I-1 frame, which actually means that all but the last frame are inlined - consistent with the change you have made here. Consider making a separate NFC change to add a comment to DIInliningInfo?

[snehasish]

In D121830#3387825, @tejohnson wrote:

lgtm

Unfortunately the ordering is not documented on the DIInliningInfo class. And confusingly, one piece of code sets an Inlined flag by the check "I > 0" (https://github.com/llvm/llvm-project/blob/49c048add4c980936fc2918838288ae2d795587d/llvm/lib/DebugInfo/Symbolize/DIPrinter.cpp#L198).
However, if I look at how that flag is used, it is used to print "(inlined by)" *before* the current frame's function name, so it seems to apply to the I-1 frame, which actually means that all but the last frame are inlined - consistent with the change you have made here. Consider making a separate NFC change to add a comment to DIInliningInfo?

Sent https://reviews.llvm.org/D122033 to add a comment to getFrame(). Thanks for taking the time to examine existing usage to double check!

llvm/lib/ProfileData/RawMemProfReader.cpp

for (const uint64_t VAddr : Entry.getSecond()) {
 
       // Drop frames which we can't symbolize or if they belong to the runtime.
       if (DI.getFrame(0).FunctionName == DILineInfo::BadString ||
           isRuntimePath(DI.getFrame(0).FileName)) {
         AllVAddrsToDiscard.insert(VAddr);
         continue;
       }
 
-      for (size_t I = 0; I < DI.getNumberOfFrames(); I++) {
+      for (size_t I = 0, NumFrames = DI.getNumberOfFrames(); I < NumFrames;
+           I++) {
         const auto &Frame = DI.getFrame(I);
         LLVM_DEBUG(
             // Print out the name to guid mapping for debugging.
             llvm::dbgs() << "FunctionName: " << Frame.FunctionName << " GUID: "
                          << Function::getGUID(trimSuffix(Frame.FunctionName))
                          << "\n";);
         SymbolizedFrame[VAddr].emplace_back(
             // We use the function guid which we expect to be a uint64_t. At
             // this time, it is the lower 64 bits of the md5 of the function
             // name. Any suffix with .llvm. is trimmed since these are added by
             // thinLTO global promotion. At the time the profile is consumed,
             // these suffixes will not be present.
             Function::getGUID(trimSuffix(Frame.FunctionName)),
             Frame.Line - Frame.StartLine, Frame.Column,
-            // Only the first entry is not an inlined location.
-            I != 0);
+            // Only the last entry is not an inlined location.
+            I != NumFrames - 1);
       }
     }
 
     auto &CallStack = Entry.getSecond();
     CallStack.erase(std::remove_if(CallStack.begin(), CallStack.end(),
                                    [&AllVAddrsToDiscard](const uint64_t A) {
                                      return AllVAddrsToDiscard.contains(A);
                                    }),

llvm/unittests/ProfileData/MemProfTest.cpp

TEST(MemProf, FillsValue) {
   std::vector<MemProfRecord> Records;
   for (const MemProfRecord &R : Reader) {
     Records.push_back(R);
   }
   EXPECT_EQ(Records.size(), 2U);
 
   EXPECT_EQ(Records[0].Info.getAllocCount(), 1U);
   EXPECT_EQ(Records[1].Info.getAllocCount(), 2U);
-  EXPECT_THAT(Records[0].CallStack[0], FrameContains("foo", 5U, 30U, false));
-  EXPECT_THAT(Records[0].CallStack[1], FrameContains("bar", 51U, 20U, true));
+  EXPECT_THAT(Records[0].CallStack[0], FrameContains("foo", 5U, 30U, true));
+  EXPECT_THAT(Records[0].CallStack[1], FrameContains("bar", 51U, 20U, false));
 
-  EXPECT_THAT(Records[1].CallStack[0], FrameContains("baz", 5U, 30U, false));
-  EXPECT_THAT(Records[1].CallStack[1], FrameContains("qux", 5U, 10U, true));
-  EXPECT_THAT(Records[1].CallStack[2], FrameContains("foo", 5U, 30U, false));
-  EXPECT_THAT(Records[1].CallStack[3], FrameContains("bar", 51U, 20U, true));
+  EXPECT_THAT(Records[1].CallStack[0], FrameContains("baz", 5U, 30U, true));
+  EXPECT_THAT(Records[1].CallStack[1], FrameContains("qux", 5U, 10U, false));
+  EXPECT_THAT(Records[1].CallStack[2], FrameContains("foo", 5U, 30U, true));
+  EXPECT_THAT(Records[1].CallStack[3], FrameContains("bar", 51U, 20U, false));
 }
 
 TEST(MemProf, PortableWrapper) {
   MemInfoBlock Info(/*size=*/16, /*access_count=*/7, /*alloc_timestamp=*/1000,
                     /*dealloc_timestamp=*/2000, /*alloc_cpu=*/3,
                     /*dealloc_cpu=*/4);
 
   const auto Schema = getFullSchema();