[PATCH] D85664: [SampleFDO] Stop letting findCalleeFunctionSamples return unrelated profiles for invoke instructions

[Wei Mi via Phabricator via llvm-commits]

wmi created this revision.
wmi added reviewers: hoyFB, wenlei, davidxl.
Herald added subscribers: hiraditya, aprantl.
Herald added a project: LLVM.
wmi requested review of this revision.

We see a warning of "No debug information found in function foo: Function profile not used" in a case. The function foo is called by an invoke instruction. It has no debug information because it has __attribute__((nodebug)) in the definition. It shouldn't have profile instance in the sample profile but compiler thinks it does, that turns out to be a compiler bug in findCalleeFunctionSamples.  The bug is exposed when sample-profile-merge-inlinee is enabled recently.

Currently in findCalleeFunctionSamples, CalleeName is unset and is empty for invoke instruction. For empty CalleeName, findFunctionSamplesAt will treat the call as an indirect call and will return any inline instance profile at the same location as the instruction. That leads to a wrong profile being returned to function foo.

The patch set CalleeName when the instruction is an invoke.


Repository:
  rL LLVM

https://reviews.llvm.org/D85664

Files:
  llvm/lib/Transforms/IPO/SampleProfile.cpp
  llvm/test/Transforms/SampleProfile/nodebug-error.ll


Index: llvm/test/Transforms/SampleProfile/nodebug-error.ll
===================================================================
--- /dev/null
+++ llvm/test/Transforms/SampleProfile/nodebug-error.ll
@@ -0,0 +1,60 @@
+; Test the profile _Z3sumii won't be mistakenly annotated to foo
+; when '-sample-profile-merge-inlinee' is enabled. When the mistake
+; happens, there will be a "No debug information found" warning message.
+; RUN: opt < %s -passes=sample-profile \
+; RUN:   -sample-profile-file=%S/Inputs/inline-mergeprof.prof \
+; RUN:   -sample-profile-merge-inlinee=true -S 2>&1| FileCheck %s
+
+ at .str = private unnamed_addr constant [11 x i8] c"sum is %d\0A\00", align 1
+declare void @__cxa_call_unexpected(i8*)
+declare i32 @__gxx_personality_v0(...)
+declare i32 @_Z3subii(i32 %x, i32 %y)
+
+define i32 @main() "use-sample-profile" nounwind uwtable ssp personality i8* bitcast (i32 (...)* @__gxx_personality_v0 to i8*) !dbg !6 {
+entry:
+  %retval = alloca i32, align 4
+  %s = alloca i32, align 4
+  %i = alloca i32, align 4
+  %tmp = load i32, i32* %i, align 4, !dbg !8
+  %tmp1 = load i32, i32* %s, align 4, !dbg !8
+  %call = invoke i32 @foo(i32 %tmp, i32 %tmp1)
+          to label %cont unwind label %lpad, !dbg !8
+; CHECK-NOT: warning: No debug information found in function foo
+; CHECK: invoke i32 @foo
+cont:
+  store i32 %call, i32* %s, align 4, !dbg !8
+  ret i32 0, !dbg !11
+lpad:
+  %lptmp0 = landingpad { i8*, i32 }
+          filter [0 x i8*] zeroinitializer
+  %lptmp1 = extractvalue { i8*, i32 } %lptmp0, 0
+  tail call void @__cxa_call_unexpected(i8* %lptmp1) noreturn nounwind
+  unreachable
+}
+
+define i32 @foo(i32 %x, i32 %y) #0 {
+entry:
+  %add = add nsw i32 %x, %y
+  ret i32 %add
+}
+
+attributes #0 = { "use-sample-profile" }
+
+declare i32 @printf(i8*, ...)
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!3, !4}
+!llvm.ident = !{!5}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "clang version 3.5 ", isOptimized: false, runtimeVersion: 0, emissionKind: NoDebug, enums: !2, retainedTypes: !2, globals: !2, imports: !2)
+!1 = !DIFile(filename: "calls.cc", directory: ".")
+!2 = !{}
+!3 = !{i32 2, !"Dwarf Version", i32 4}
+!4 = !{i32 1, !"Debug Info Version", i32 3}
+!5 = !{!"clang version 3.5 "}
+!6 = distinct !DISubprogram(name: "main", scope: !1, file: !1, line: 7, type: !7, scopeLine: 7, virtualIndex: 6, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition, unit: !0, retainedNodes: !2)
+!7 = !DISubroutineType(types: !2)
+!8 = !DILocation(line: 10, scope: !9)
+!9 = !DILexicalBlockFile(scope: !10, file: !1, discriminator: 2)
+!10 = distinct !DILexicalBlock(scope: !6, file: !1, line: 10)
+!11 = !DILocation(line: 12, scope: !6)
Index: llvm/lib/Transforms/IPO/SampleProfile.cpp
===================================================================
--- llvm/lib/Transforms/IPO/SampleProfile.cpp
+++ llvm/lib/Transforms/IPO/SampleProfile.cpp
@@ -820,9 +820,8 @@
   }
 
   StringRef CalleeName;
-  if (const CallInst *CI = dyn_cast<CallInst>(&Inst))
-    if (Function *Callee = CI->getCalledFunction())
-      CalleeName = Callee->getName();
+  if (Function *Callee = Inst.getCalledFunction())
+    CalleeName = Callee->getName();
 
   const FunctionSamples *FS = findFunctionSamples(Inst);
   if (FS == nullptr)


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