[InstrPGO][TypeProf]Annotate vtable types when they are present in the profile (#99402)

Before this change, when `file.profdata` have vtable profiles but `--enable-vtable-value-profiling` is not on for optimized build, warnings from this line [1] will show up. They are benign for performance but confusing.

It's better to automatically annotate vtable profiles if `file.profdata` has them. This PR implements it in profile use pass.
* If `-icp-max-num-vtables` is zero (default value is 6), vtable profiles won't be annotated.

[1] https://github.com/llvm/llvm-project/blob/464d321ee8dde1eaf14b5537eaf030e6df513849/llvm/lib/Transforms/Instrumentation/PGOInstrumentation.cpp#L1762-L1768

Author: mingmingl-llvm

compiler-rt/test/profile/Linux/instrprof-vtable-value-prof.cpp

@@ -109,6 +109,25 @@
 // ICTEXT: {{.*}}instrprof-vtable-value-prof.cpp;_ZTVN12_GLOBAL__N_18Derived2E:750
 // ICTEXT: _ZTV8Derived1:250
 
+// When vtable value profiles exist, pgo-instr-use pass should annotate them
+// even if `-enable-vtable-value-profiling` is not explicitly on.
+// RUN: %clangxx -m64 -fprofile-use=test.profdata -fuse-ld=lld -O2 \
+// RUN:   -mllvm -print-after=pgo-instr-use -mllvm -filter-print-funcs=main \
+// RUN:   -mllvm -print-module-scope %s 2>&1 | FileCheck %s --check-prefix=ANNOTATE
+
+// ANNOTATE-NOT: Inconsistent number of value sites
+// ANNOTATE: !{!"VP", i32 2
+
+// When vtable value profiles exist, pgo-instr-use pass will not annotate them
+// if `-icp-max-num-vtables` is set to zero.
+// RUN: %clangxx -m64 -fprofile-use=test.profdata -fuse-ld=lld -O2 \
+// RUN:   -mllvm -icp-max-num-vtables=0 -mllvm -print-after=pgo-instr-use \
+// RUN:   -mllvm -filter-print-funcs=main -mllvm -print-module-scope %s 2>&1 | \
+// RUN:   FileCheck %s --check-prefix=OMIT
+
+// OMIT: Inconsistent number of value sites
+// OMIT-NOT: !{!"VP", i32 2
+
 // Test indirect call promotion transformation using vtable profiles.
 // - Build with `-g` to enable debug information.
 // - In real world settings, ICP pass is disabled in prelink pipeline. In
@@ -128,12 +147,12 @@
 // RUN:    | FileCheck %s --check-prefixes=REMARK,IR --implicit-check-not="!VP"
 
 // For the indirect call site `ptr->func`
-// REMARK: instrprof-vtable-value-prof.cpp:205:19: Promote indirect call to _ZN12_GLOBAL__N_18Derived24funcEii with count 150 out of 200, sink 1 instruction(s) and compare 1 vtable(s): {_ZTVN12_GLOBAL__N_18Derived2E}
-// REMARK: instrprof-vtable-value-prof.cpp:205:19: Promote indirect call to _ZN8Derived14funcEii with count 50 out of 50, sink 1 instruction(s) and compare 1 vtable(s): {_ZTV8Derived1}
+// REMARK: instrprof-vtable-value-prof.cpp:226:19: Promote indirect call to _ZN12_GLOBAL__N_18Derived24funcEii with count 150 out of 200, sink 1 instruction(s) and compare 1 vtable(s): {_ZTVN12_GLOBAL__N_18Derived2E}
+// REMARK: instrprof-vtable-value-prof.cpp:226:19: Promote indirect call to _ZN8Derived14funcEii with count 50 out of 50, sink 1 instruction(s) and compare 1 vtable(s): {_ZTV8Derived1}
 //
 // For the indirect call site `delete ptr`
-// REMARK: instrprof-vtable-value-prof.cpp:207:5: Promote indirect call to _ZN12_GLOBAL__N_18Derived2D0Ev with count 750 out of 1000, sink 2 instruction(s) and compare 1 vtable(s): {_ZTVN12_GLOBAL__N_18Derived2E}
-// REMARK: instrprof-vtable-value-prof.cpp:207:5: Promote indirect call to _ZN8Derived1D0Ev with count 250 out of 250, sink 2 instruction(s) and compare 1 vtable(s): {_ZTV8Derived1}
+// REMARK: instrprof-vtable-value-prof.cpp:228:5: Promote indirect call to _ZN12_GLOBAL__N_18Derived2D0Ev with count 750 out of 1000, sink 2 instruction(s) and compare 1 vtable(s): {_ZTVN12_GLOBAL__N_18Derived2E}
+// REMARK: instrprof-vtable-value-prof.cpp:228:5: Promote indirect call to _ZN8Derived1D0Ev with count 250 out of 250, sink 2 instruction(s) and compare 1 vtable(s): {_ZTV8Derived1}
 
 // The IR matchers for indirect callsite `ptr->func`.
 // IR-LABEL: @main

llvm/lib/Transforms/Instrumentation/PGOInstrumentation.cpp

@@ -1096,7 +1096,7 @@ class PGOUseFunc {
       : F(Func), M(Modu), BFI(BFIin), PSI(PSI),
         FuncInfo(Func, TLI, ComdatMembers, false, BPI, BFIin, IsCS,
                  InstrumentFuncEntry, HasSingleByteCoverage),
-        FreqAttr(FFA_Normal), IsCS(IsCS) {}
+        FreqAttr(FFA_Normal), IsCS(IsCS), VPC(Func, TLI) {}
 
   void handleInstrProfError(Error Err, uint64_t MismatchedFuncSum);
 
@@ -1178,6 +1178,8 @@ class PGOUseFunc {
   // Is to use the context sensitive profile.
   bool IsCS;
 
+  ValueProfileCollector VPC;
+
   // Find the Instrumented BB and set the value. Return false on error.
   bool setInstrumentedCounts(const std::vector<uint64_t> &CountFromProfile);
 
@@ -1755,8 +1757,23 @@ void PGOUseFunc::annotateValueSites() {
 void PGOUseFunc::annotateValueSites(uint32_t Kind) {
   assert(Kind <= IPVK_Last);
   unsigned ValueSiteIndex = 0;
-  auto &ValueSites = FuncInfo.ValueSites[Kind];
+
   unsigned NumValueSites = ProfileRecord.getNumValueSites(Kind);
+
+  // Since there isn't a reliable or fast way for profile reader to tell if a
+  // profile is generated with `-enable-vtable-value-profiling` on, we run the
+  // value profile collector over the function IR to find the instrumented sites
+  // iff function profile records shows the number of instrumented vtable sites
+  // is not zero. Function cfg already takes the number of instrumented
+  // indirect call sites into account so it doesn't hash the number of
+  // instrumented vtables; as a side effect it makes it easier to enable
+  // profiling and profile use in two steps if needed.
+  // TODO: Remove this if/when -enable-vtable-value-profiling is on by default.
+  if (NumValueSites > 0 && Kind == IPVK_VTableTarget &&
+      NumValueSites != FuncInfo.ValueSites[IPVK_VTableTarget].size() &&
+      MaxNumVTableAnnotations != 0)
+    FuncInfo.ValueSites[IPVK_VTableTarget] = VPC.get(IPVK_VTableTarget);
+  auto &ValueSites = FuncInfo.ValueSites[Kind];
   if (NumValueSites != ValueSites.size()) {
     auto &Ctx = M->getContext();
     Ctx.diagnose(DiagnosticInfoPGOProfile(