[SampleProfile] Repeat indirect call promotion only when the target is actually hot.

[twoh]

Summary

It is possible that multiple indirect call targets have been promoted for a single callsite from the profiled binary. Current implementation repeats promotion for all these targets as far as the callsite itself is hot (the callsite is assumed to be hot if any one of these targets was "hot" during the profiling). However, even when one of the ICPed target is hot other targets may not, and we should not repeat promotion for "cold" targets.

[twoh]

Remove unnecessary metadata.

[wmi]

Thanks! The change makes a lot sense to me.

llvm/test/Transforms/SampleProfile/cold-indirect-call.ll

2

Could you add the check for new pass manager too?

[twoh]

Check for the new pass manager added. Thanks @wmi for the comment!

llvm/lib/Transforms/IPO/SampleProfile.cpp

for (auto I : CIS) {
           // If it is a recursive call, we do not inline it as it could bloat
           // the code exponentially. There is way to better handle this, e.g.
           // clone the caller first, and inline the cloned caller if it is
           // recursive. As llvm does not inline recursive calls, we will
           // simply ignore it instead of handling it explicitly.
           if (CalleeFunctionName == F.getName())
             continue;
 
+          if (!callsiteIsHot(FS, PSI))
+            continue;
+
           const char *Reason = "Callee function not available";
           auto R = SymbolMap.find(CalleeFunctionName);
           if (R != SymbolMap.end() && R->getValue() &&
               !R->getValue()->isDeclaration() &&
               R->getValue()->getSubprogram() &&
               isLegalToPromote(CallSite(I), R->getValue(), &Reason)) {
             uint64_t C = FS->getEntrySamples();
             Instruction *DI =

llvm/test/Transforms/SampleProfile/Inputs/cold-indirect-call.prof

+foo:5000:1
+ 1: 2000 quz:1000
+ 1: bar:3000
+   1: 3000
+ 1: baz:0
+   1: 0

llvm/test/Transforms/SampleProfile/cold-indirect-call.ll

+; RUN: opt < %s -sample-profile -sample-profile-file=%S/Inputs/cold-indirect-call.prof -S | FileCheck %s
+; RUN: opt < %s -passes=sample-profile -sample-profile-file=%S/Inputs/cold-indirect-call.prof -S | FileCheck %s
+
+define i32 @foo(i32 ()* %func) !dbg !3 {
+; CHECK: icmp {{.*}} @bar
+; CHECK-NOT: icmp {{.*}} @baz
+  %call = call i32 %func(), !dbg !4
+  ret i32 %call
+}
+
+define i32 @bar() !dbg !5 {
+  ret i32 41, !dbg !6
+}
+
+define i32 @baz() !dbg !7 {
+  ret i32 42, !dbg !8
+}
+
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!2}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1)
+!1 = !DIFile(filename: "foo.cc", directory: "/")
+!2 = !{i32 2, !"Debug Info Version", i32 3}
+!3 = distinct !DISubprogram(name: "foo", scope: !1, file: !1, line: 4, unit: !0)
+!4 = !DILocation(line: 5, scope: !3)
+!5 = distinct !DISubprogram(name: "bar", scope: !1, file: !1, line: 8, unit: !0)
+!6 = !DILocation(line: 9, scope: !5)
+!7 = distinct !DISubprogram(name: "baz", scope: !1, file: !1, line: 12, unit: !0)
+!8 = !DILocation(line: 13, scope: !7)