[CSSPGO] Turn on call-graph matching by default for CSSPGO (#125938)

Tested call-graph matching on some of Meta's large services, it works to
reuse some renamed function profiles, no negative perf or significant
build speed regression observed. Turned it on by default for CSSPGO
mode.

Author: wlei-llvm

llvm/lib/Transforms/IPO/SampleProfile.cpp

@@ -2045,9 +2045,11 @@ bool SampleProfileLoader::doInitialization(Module &M,
     // which is currently only available for pseudo-probe mode. Removing the
     // checksum check could cause regressions for some cases, so further tuning
     // might be needed if we want to enable it for all cases.
-    if (Reader->profileIsProbeBased() &&
-        !SalvageStaleProfile.getNumOccurrences()) {
-      SalvageStaleProfile = true;
+    if (Reader->profileIsProbeBased()) {
+      if (!SalvageStaleProfile.getNumOccurrences())
+        SalvageStaleProfile = true;
+      if (!SalvageUnusedProfile.getNumOccurrences())
+        SalvageUnusedProfile = true;
     }
 
     if (!Reader->profileIsCS()) {

llvm/lib/Transforms/IPO/SampleProfileMatcher.cpp

@@ -38,7 +38,7 @@ static cl::opt<unsigned> MinCallCountForCGMatching(
              "run stale profile call graph matching."));
 
 static cl::opt<bool> LoadFuncProfileforCGMatching(
-    "load-func-profile-for-cg-matching", cl::Hidden, cl::init(false),
+    "load-func-profile-for-cg-matching", cl::Hidden, cl::init(true),
     cl::desc(
         "Load top-level profiles that the sample reader initially skipped for "
         "the call-graph matching (only meaningful for extended binary "

llvm/test/Transforms/SampleProfile/pseudo-probe-callee-profile-mismatch.ll

@@ -1,6 +1,6 @@
 ; REQUIRES: x86_64-linux
 ; REQUIRES: asserts
-; RUN: opt < %s -passes='thinlto<O2>' -pgo-kind=pgo-sample-use-pipeline  -sample-profile-file=%S/Inputs/pseudo-probe-callee-profile-mismatch.prof --salvage-stale-profile -S --debug-only=sample-profile,sample-profile-matcher,sample-profile-impl  -pass-remarks=inline 2>&1 | FileCheck %s
+; RUN: opt < %s -passes='thinlto<O2>' -pgo-kind=pgo-sample-use-pipeline  -sample-profile-file=%S/Inputs/pseudo-probe-callee-profile-mismatch.prof --salvage-stale-profile --salvage-unused-profile=false -S --debug-only=sample-profile,sample-profile-matcher,sample-profile-impl  -pass-remarks=inline 2>&1 | FileCheck %s
 
 ; There is no profile-checksum-mismatch attr, even the checksum is mismatched in the pseudo_probe_desc, it doesn't run the matching.
 ; CHECK-NOT: Run stale profile matching for main

llvm/test/Transforms/SampleProfile/pseudo-probe-profile-mismatch-thinlto.ll

@@ -1,5 +1,5 @@
 ; REQUIRES: x86_64-linux
-; RUN: opt < %S/pseudo-probe-stale-profile-matching-lto.ll -passes='thinlto<O2>' -pgo-kind=pgo-sample-use-pipeline -sample-profile-file=%S/Inputs/pseudo-probe-stale-profile-matching-lto.prof -report-profile-staleness -persist-profile-staleness  -S 2>%t -o %t.ll
+; RUN: opt < %S/pseudo-probe-stale-profile-matching-lto.ll -passes='thinlto<O2>' -pgo-kind=pgo-sample-use-pipeline  --salvage-unused-profile=false -sample-profile-file=%S/Inputs/pseudo-probe-stale-profile-matching-lto.prof -report-profile-staleness -persist-profile-staleness  -S 2>%t -o %t.ll
 ; RUN: FileCheck %s --input-file %t
 ; RUN: FileCheck %s --input-file %t.ll -check-prefix=CHECK-MD
 

llvm/test/Transforms/SampleProfile/pseudo-probe-profile-mismatch.ll

@@ -1,12 +1,12 @@
 ; REQUIRES: x86_64-linux
-; RUN: opt < %s -passes=sample-profile -sample-profile-file=%S/Inputs/pseudo-probe-profile-mismatch.prof -report-profile-staleness -persist-profile-staleness -S 2>%t -o %t.ll
+; RUN: opt < %s -passes=sample-profile -sample-profile-file=%S/Inputs/pseudo-probe-profile-mismatch.prof --salvage-unused-profile=false -report-profile-staleness -persist-profile-staleness -S 2>%t -o %t.ll
 ; RUN: FileCheck %s --input-file %t
 ; RUN: FileCheck %s --input-file %t.ll -check-prefix=CHECK-MD
 ; RUN: llc < %t.ll -filetype=obj -o %t.obj
 ; RUN: llvm-objdump --section-headers %t.obj | FileCheck %s --check-prefix=CHECK-OBJ
 ; RUN: llc < %t.ll -filetype=asm -o - | FileCheck %s --check-prefix=CHECK-ASM
 
-; RUN: opt < %s -passes=sample-profile -sample-profile-file=%S/Inputs/pseudo-probe-profile-mismatch-nested.prof -report-profile-staleness -persist-profile-staleness -S 2>&1 | FileCheck %s --check-prefix=CHECK-NESTED
+; RUN: opt < %s -passes=sample-profile -sample-profile-file=%S/Inputs/pseudo-probe-profile-mismatch-nested.prof --salvage-unused-profile=false -report-profile-staleness -persist-profile-staleness -S 2>&1 | FileCheck %s --check-prefix=CHECK-NESTED
 
 
 ; CHECK: (2/3) of functions' profile are invalid and (40/50) of samples are discarded due to function hash mismatch.