[PATCH] D112948: [SamplePGO] Fix callsite sample lookup to use dwarf names when dwarf linkage name isn't available.

[Hongtao Yu via Phabricator via llvm-commits]

hoy created this revision.
Herald added subscribers: modimo, wenlei, hiraditya.
hoy requested review of this revision.
Herald added a project: LLVM.
Herald added a subscriber: llvm-commits.

When linkage name isn't available in dwarf (ususally the case of C code),  looking up callee samples should be based on the dwarf name instead of using an empty string.

Also fixing a test issue where using empty string to look up callee samples accidentally returns the correct samples because it is treated as indirect call.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D112948

Files:
  llvm/lib/ProfileData/SampleProf.cpp
  llvm/test/Transforms/SampleProfile/profile-format-compress.ll
  llvm/test/Transforms/SampleProfile/profile-format.ll


Index: llvm/test/Transforms/SampleProfile/profile-format.ll
===================================================================
--- llvm/test/Transforms/SampleProfile/profile-format.ll
+++ llvm/test/Transforms/SampleProfile/profile-format.ll
@@ -110,7 +110,7 @@
 !0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, producer: "clang version 3.5 ", isOptimized: false, emissionKind: NoDebug, file: !1, enums: !2, retainedTypes: !2, globals: !2, imports: !2)
 !1 = !DIFile(filename: "calls.cc", directory: ".")
 !2 = !{}
-!4 = distinct !DISubprogram(name: "sum", line: 3, isLocal: false, isDefinition: true, virtualIndex: 6, flags: DIFlagPrototyped, isOptimized: false, unit: !0, scopeLine: 3, file: !1, scope: !5, type: !6, retainedNodes: !2)
+!4 = distinct !DISubprogram(name: "sum", linkageName: "_Z3sumii", line: 3, isLocal: false, isDefinition: true, virtualIndex: 6, flags: DIFlagPrototyped, isOptimized: false, unit: !0, scopeLine: 3, file: !1, scope: !5, type: !6, retainedNodes: !2)
 !5 = !DIFile(filename: "calls.cc", directory: ".")
 !6 = !DISubroutineType(types: !2)
 !7 = distinct !DISubprogram(name: "main", line: 7, isLocal: false, isDefinition: true, virtualIndex: 6, flags: DIFlagPrototyped, isOptimized: false, unit: !0, scopeLine: 7, file: !1, scope: !5, type: !6, retainedNodes: !2)
Index: llvm/test/Transforms/SampleProfile/profile-format-compress.ll
===================================================================
--- llvm/test/Transforms/SampleProfile/profile-format-compress.ll
+++ llvm/test/Transforms/SampleProfile/profile-format-compress.ll
@@ -101,7 +101,7 @@
 !0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, producer: "clang version 3.5 ", isOptimized: false, emissionKind: NoDebug, file: !1, enums: !2, retainedTypes: !2, globals: !2, imports: !2)
 !1 = !DIFile(filename: "calls.cc", directory: ".")
 !2 = !{}
-!4 = distinct !DISubprogram(name: "sum", line: 3, isLocal: false, isDefinition: true, virtualIndex: 6, flags: DIFlagPrototyped, isOptimized: false, unit: !0, scopeLine: 3, file: !1, scope: !5, type: !6, retainedNodes: !2)
+!4 = distinct !DISubprogram(name: "sum", linkageName: "_Z3sumii", line: 3, isLocal: false, isDefinition: true, virtualIndex: 6, flags: DIFlagPrototyped, isOptimized: false, unit: !0, scopeLine: 3, file: !1, scope: !5, type: !6, retainedNodes: !2)
 !5 = !DIFile(filename: "calls.cc", directory: ".")
 !6 = !DISubroutineType(types: !2)
 !7 = distinct !DISubprogram(name: "main", line: 7, isLocal: false, isDefinition: true, virtualIndex: 6, flags: DIFlagPrototyped, isOptimized: false, unit: !0, scopeLine: 7, file: !1, scope: !5, type: !6, retainedNodes: !2)
Index: llvm/lib/ProfileData/SampleProf.cpp
===================================================================
--- llvm/lib/ProfileData/SampleProf.cpp
+++ llvm/lib/ProfileData/SampleProf.cpp
@@ -219,7 +219,7 @@
 }
 
 LineLocation FunctionSamples::getCallSiteIdentifier(const DILocation *DIL) {
-  if (FunctionSamples::ProfileIsProbeBased)
+  if (FunctionSamples::ProfileIsProbeBased) {
     // In a pseudo-probe based profile, a callsite is simply represented by the
     // ID of the probe associated with the call instruction. The probe ID is
     // encoded in the Discriminator field of the call instruction's debug
@@ -227,9 +227,16 @@
     return LineLocation(PseudoProbeDwarfDiscriminator::extractProbeIndex(
                             DIL->getDiscriminator()),
                         0);
-  else
+  }
+  else {
+    unsigned Discriminator;
+    if (ProfileIsFS)
+      Discriminator = DIL->getDiscriminator();
+    else
+      Discriminator = DIL->getBaseDiscriminator();
     return LineLocation(FunctionSamples::getOffset(DIL),
-                        DIL->getBaseDiscriminator());
+                        Discriminator);  
+  }
 }
 
 const FunctionSamples *FunctionSamples::findFunctionSamples(
@@ -239,15 +246,12 @@
 
   const DILocation *PrevDIL = DIL;
   for (DIL = DIL->getInlinedAt(); DIL; DIL = DIL->getInlinedAt()) {
-    unsigned Discriminator;
-    if (ProfileIsFS)
-      Discriminator = DIL->getDiscriminator();
-    else
-      Discriminator = DIL->getBaseDiscriminator();
-
+    // Use C++ linkage name if possible.
+    StringRef Name = PrevDIL->getScope()->getSubprogram()->getLinkageName();
+    if (Name.empty())
+      Name = PrevDIL->getScope()->getSubprogram()->getName();
     S.push_back(
-        std::make_pair(LineLocation(getOffset(DIL), Discriminator),
-                       PrevDIL->getScope()->getSubprogram()->getLinkageName()));
+        std::make_pair(FunctionSamples::getCallSiteIdentifier(DIL), Name));
     PrevDIL = DIL;
   }
   if (S.size() == 0)


-------------- next part --------------
A non-text attachment was scrubbed...
Name: D112948.383857.patch
Type: text/x-patch
Size: 4646 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20211101/d0523c7d/attachment.bin>