[llvm] d137854 - [SamplePGO] Fix callsite sample lookup to use dwarf names when dwarf linkage name isn't available.

[Hongtao Yu via llvm-commits]

Author: Hongtao Yu
Date: 2021-11-01T21:24:33-07:00
New Revision: d137854412533d9c01c2ef9795ae6514a66c2d8b

URL: https://github.com/llvm/llvm-project/commit/d137854412533d9c01c2ef9795ae6514a66c2d8b
DIFF: https://github.com/llvm/llvm-project/commit/d137854412533d9c01c2ef9795ae6514a66c2d8b.diff

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

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.

Reviewed By: wenlei

Differential Revision: https://reviews.llvm.org/D112948

Added: 
    

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

Removed: 
    


################################################################################
diff  --git a/llvm/lib/ProfileData/SampleProf.cpp b/llvm/lib/ProfileData/SampleProf.cpp
index cb5dd92913205..fd8fd3b675b78 100644
--- a/llvm/lib/ProfileData/SampleProf.cpp
+++ b/llvm/lib/ProfileData/SampleProf.cpp
@@ -245,9 +245,13 @@ const FunctionSamples *FunctionSamples::findFunctionSamples(
     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(LineLocation(getOffset(DIL), Discriminator), Name));
     PrevDIL = DIL;
   }
   if (S.size() == 0)

diff  --git a/llvm/test/Transforms/SampleProfile/profile-format-compress.ll b/llvm/test/Transforms/SampleProfile/profile-format-compress.ll
index 8303db8f8888e..be4e27c9641b2 100644
--- a/llvm/test/Transforms/SampleProfile/profile-format-compress.ll
+++ b/llvm/test/Transforms/SampleProfile/profile-format-compress.ll
@@ -101,7 +101,7 @@ attributes #0 = { "use-sample-profile" }
 !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)

diff  --git a/llvm/test/Transforms/SampleProfile/profile-format.ll b/llvm/test/Transforms/SampleProfile/profile-format.ll
index 72765c3054907..f0df061e12145 100644
--- a/llvm/test/Transforms/SampleProfile/profile-format.ll
+++ b/llvm/test/Transforms/SampleProfile/profile-format.ll
@@ -110,7 +110,7 @@ attributes #0 = { "use-sample-profile" }
 !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)