Merging r372020 and r372182:release_90

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r372020 | rnk | 2019-09-16 11:49:09 -0700 (Mon, 16 Sep 2019) | 30 lines

[PGO] Use linkonce_odr linkage for __profd_ variables in comdat groups

This fixes relocations against __profd_ symbols in discarded sections,
which is PR41380.

In general, instrumentation happens very early, and optimization and
inlining happens afterwards. The counters for a function are calculated
early, and after inlining, counters for an inlined function may be
widely referenced by other functions.

For C++ inline functions of all kinds (linkonce_odr &
available_externally mainly), instr profiling wants to deduplicate these
__profc_ and __profd_ globals. Otherwise the binary would be quite
large.

I made __profd_ and __profc_ comdat in r355044, but I chose to make
__profd_ internal. At the time, I was only dealing with coverage, and in
that case, none of the instrumentation needs to reference __profd_.
However, if you use PGO, then instrumentation passes add calls to
__llvm_profile_instrument_range which reference __profd_ globals. The
solution is to make these globals externally visible by using
linkonce_odr linkage for data as was done for counters.

This is safe because PGO adds a CFG hash to the names of the data and
counter globals, so if different TUs have different globals, they will
get different data and counter arrays.

Reviewers: xur, hans

Differential Revision: https://reviews.llvm.org/D67579
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r372182 | rnk | 2019-09-17 14:10:49 -0700 (Tue, 17 Sep 2019) | 12 lines

[PGO] Don't use comdat groups for counters & data on COFF

For COFF, a comdat group is really a symbol marked
IMAGE_COMDAT_SELECT_ANY and zero or more other symbols marked
IMAGE_COMDAT_SELECT_ASSOCIATIVE. Typically the associative symbols in
the group are not external and are not referenced by other TUs, they are
things like debug info, C++ dynamic initializers, or other section
registration schemes. The Visual C++ linker reports a duplicate symbol
error for symbols marked IMAGE_COMDAT_SELECT_ASSOCIATIVE even if they
would be discarded after handling the leader symbol.

Fixes coverage-inline.cpp in check-profile after r372020.
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git-svn-id: https://llvm.org/svn/llvm-project/llvm/branches/release_90@374858 91177308-0d34-0410-b5e6-96231b3b80d8

4 files changed, 31 insertions, 25 deletions

diff --git a/lib/Transforms/Instrumentation/InstrProfiling.cpp b/lib/Transforms/Instrumentation/InstrProfiling.cpp
index 63c2b8078967..5d3a793dda19 100644
--- a/lib/Transforms/Instrumentation/InstrProfiling.cpp
+++ b/lib/Transforms/Instrumentation/InstrProfiling.cpp
@@ -731,9 +731,8 @@ InstrProfiling::getOrCreateRegionCounters(InstrProfIncrementInst *Inc) {
     PD = It->second;
   }
 
-  // Match the linkage and visibility of the name global, except on COFF, where
-  // the linkage must be local and consequentially the visibility must be
-  // default.
+  // Match the linkage and visibility of the name global. COFF supports using
+  // comdats with internal symbols, so do that if we can.
   Function *Fn = Inc->getParent()->getParent();
   GlobalValue::LinkageTypes Linkage = NamePtr->getLinkage();
   GlobalValue::VisibilityTypes Visibility = NamePtr->getVisibility();
@@ -749,19 +748,25 @@ InstrProfiling::getOrCreateRegionCounters(InstrProfIncrementInst *Inc) {
   // new comdat group for the counters and profiling data. If we use the comdat
   // of the parent function, that will result in relocations against discarded
   // sections.
-  Comdat *Cmdt = nullptr;
-  GlobalValue::LinkageTypes CounterLinkage = Linkage;
-  if (needsComdatForCounter(*Fn, *M)) {
-    StringRef CmdtPrefix = getInstrProfComdatPrefix();
+  bool NeedComdat = needsComdatForCounter(*Fn, *M);
+  Comdat *Cmdt = nullptr; // Comdat group.
+  if (NeedComdat) {
     if (TT.isOSBinFormatCOFF()) {
-      // For COFF, the comdat group name must be the name of a symbol in the
-      // group. Use the counter variable name, and upgrade its linkage to
-      // something externally visible, like linkonce_odr.
-      CmdtPrefix = getInstrProfCountersVarPrefix();
-      CounterLinkage = GlobalValue::LinkOnceODRLinkage;
+      // For COFF, put the counters, data, and values each into their own
+      // comdats. We can't use a group because the Visual C++ linker will
+      // report duplicate symbol errors if there are multiple external symbols
+      // with the same name marked IMAGE_COMDAT_SELECT_ASSOCIATIVE.
+      Linkage = GlobalValue::LinkOnceODRLinkage;
+      Visibility = GlobalValue::HiddenVisibility;
+    } else {
+      // Otherwise, create one comdat group for everything.
+      Cmdt = M->getOrInsertComdat(getVarName(Inc, getInstrProfComdatPrefix()));
     }
-    Cmdt = M->getOrInsertComdat(getVarName(Inc, CmdtPrefix));
   }
+  auto MaybeSetComdat = [=](GlobalVariable *GV) {
+    if (NeedComdat)
+      GV->setComdat(Cmdt ? Cmdt : M->getOrInsertComdat(GV->getName()));
+  };
 
   uint64_t NumCounters = Inc->getNumCounters()->getZExtValue();
   LLVMContext &Ctx = M->getContext();
@@ -776,8 +781,8 @@ InstrProfiling::getOrCreateRegionCounters(InstrProfIncrementInst *Inc) {
   CounterPtr->setSection(
       getInstrProfSectionName(IPSK_cnts, TT.getObjectFormat()));
   CounterPtr->setAlignment(8);
-  CounterPtr->setComdat(Cmdt);
-  CounterPtr->setLinkage(CounterLinkage);
+  MaybeSetComdat(CounterPtr);
+  CounterPtr->setLinkage(Linkage);
 
   auto *Int8PtrTy = Type::getInt8PtrTy(Ctx);
   // Allocate statically the array of pointers to value profile nodes for
@@ -798,7 +803,7 @@ InstrProfiling::getOrCreateRegionCounters(InstrProfIncrementInst *Inc) {
       ValuesVar->setSection(
           getInstrProfSectionName(IPSK_vals, TT.getObjectFormat()));
       ValuesVar->setAlignment(8);
-      ValuesVar->setComdat(Cmdt);
+      MaybeSetComdat(ValuesVar);
       ValuesPtrExpr =
           ConstantExpr::getBitCast(ValuesVar, Type::getInt8PtrTy(Ctx));
     }
@@ -831,7 +836,8 @@ InstrProfiling::getOrCreateRegionCounters(InstrProfIncrementInst *Inc) {
   Data->setVisibility(Visibility);
   Data->setSection(getInstrProfSectionName(IPSK_data, TT.getObjectFormat()));
   Data->setAlignment(INSTR_PROF_DATA_ALIGNMENT);
-  Data->setComdat(Cmdt);
+  MaybeSetComdat(Data);
+  Data->setLinkage(Linkage);
 
   PD.RegionCounters = CounterPtr;
   PD.DataVar = Data;
diff --git a/test/Instrumentation/InstrProfiling/PR23499.ll b/test/Instrumentation/InstrProfiling/PR23499.ll
index af95f9a45580..a5e20b10c3ef 100644
--- a/test/Instrumentation/InstrProfiling/PR23499.ll
+++ b/test/Instrumentation/InstrProfiling/PR23499.ll
@@ -20,8 +20,8 @@ $_Z3barIvEvv = comdat any
 
 
 ; COFF-NOT: __profn__Z3barIvEvv
-; COFF: @__profc__Z3barIvEvv = linkonce_odr dso_local global [1 x i64] zeroinitializer, section "{{.*}}prfc$M", comdat, align 8
-; COFF: @__profd__Z3barIvEvv = internal global { i64, i64, i64*, i8*, i8*, i32, [2 x i16] } { i64 4947693190065689389, i64 0, i64* getelementptr inbounds ([1 x i64], [1 x i64]* @__profc__Z3barIvEvv, i32 0, i32 0), i8*{{.*}}, i8* null, i32 1, [2 x i16] zeroinitializer }, section "{{.*}}prfd{{.*}}", comdat($__profc__Z3barIvEvv), align 8
+; COFF: @__profc__Z3barIvEvv = linkonce_odr hidden global [1 x i64] zeroinitializer, section "{{.*}}prfc$M", comdat, align 8
+; COFF: @__profd__Z3barIvEvv = linkonce_odr hidden global { i64, i64, i64*, i8*, i8*, i32, [2 x i16] } { i64 4947693190065689389, i64 0, i64* getelementptr inbounds ([1 x i64], [1 x i64]* @__profc__Z3barIvEvv, i32 0, i32 0), i8*{{.*}}, i8* null, i32 1, [2 x i16] zeroinitializer }, section "{{.*}}prfd{{.*}}", comdat, align 8
 
 
 declare void @llvm.instrprof.increment(i8*, i64, i32, i32) #1
diff --git a/test/Instrumentation/InstrProfiling/comdat.ll b/test/Instrumentation/InstrProfiling/comdat.ll
index 03ee905fa65c..5ff820cc0338 100644
--- a/test/Instrumentation/InstrProfiling/comdat.ll
+++ b/test/Instrumentation/InstrProfiling/comdat.ll
@@ -17,8 +17,8 @@ $foo_inline = comdat any
 
 ; ELF: @__profc_foo_inline = linkonce_odr hidden global{{.*}}, section "__llvm_prf_cnts", comdat($__profv_foo_inline), align 8
 ; ELF: @__profd_foo_inline = linkonce_odr hidden global{{.*}}, section "__llvm_prf_data", comdat($__profv_foo_inline), align 8
-; COFF: @__profc_foo_inline = linkonce_odr dso_local global{{.*}}, section ".lprfc$M", comdat, align 8
-; COFF: @__profd_foo_inline = internal global{{.*}}, section ".lprfd$M", comdat($__profc_foo_inline), align 8
+; COFF: @__profc_foo_inline = linkonce_odr hidden global{{.*}}, section ".lprfc$M", comdat, align 8
+; COFF: @__profd_foo_inline = linkonce_odr hidden global{{.*}}, section ".lprfd$M", comdat, align 8
 define weak_odr void @foo_inline() comdat {
   call void @llvm.instrprof.increment(i8* getelementptr inbounds ([10 x i8], [10 x i8]* @__profn_foo_inline, i32 0, i32 0), i64 0, i32 1, i32 0)
   ret void
@@ -30,8 +30,8 @@ $foo_extern = comdat any
 
 ; ELF: @__profc_foo_extern = linkonce_odr hidden global{{.*}}, section "__llvm_prf_cnts", comdat($__profv_foo_extern)
 ; ELF: @__profd_foo_extern = linkonce_odr hidden global{{.*}}, section "__llvm_prf_data", comdat($__profv_foo_extern)
-; COFF: @__profc_foo_extern = linkonce_odr dso_local global{{.*}}, section ".lprfc$M", comdat, align 8
-; COFF: @__profd_foo_extern = internal global{{.*}}, section ".lprfd$M", comdat($__profc_foo_extern), align 8
+; COFF: @__profc_foo_extern = linkonce_odr hidden global{{.*}}, section ".lprfc$M", comdat, align 8
+; COFF: @__profd_foo_extern = linkonce_odr hidden global{{.*}}, section ".lprfd$M", comdat, align 8
 define available_externally void @foo_extern() {
   call void @llvm.instrprof.increment(i8* getelementptr inbounds ([10 x i8], [10 x i8]* @__profn_foo_extern, i32 0, i32 0), i64 0, i32 1, i32 0)
   ret void
diff --git a/test/Instrumentation/InstrProfiling/linkage.ll b/test/Instrumentation/InstrProfiling/linkage.ll
index 29ae5d6e90cb..13e389bb4e9e 100644
--- a/test/Instrumentation/InstrProfiling/linkage.ll
+++ b/test/Instrumentation/InstrProfiling/linkage.ll
@@ -57,8 +57,8 @@ define linkonce_odr void @foo_inline() {
 ; LINUX: @__profd_foo_extern = linkonce_odr hidden global {{.*}}section "__llvm_prf_data", comdat($__profv_foo_extern), align 8
 ; MACHO: @__profc_foo_extern = linkonce_odr hidden global
 ; MACHO: @__profd_foo_extern = linkonce_odr hidden global
-; COFF: @__profc_foo_extern = linkonce_odr dso_local global {{.*}}section ".lprfc$M", comdat, align 8
-; COFF: @__profd_foo_extern = internal global {{.*}}section ".lprfd$M", comdat($__profc_foo_extern), align 8
+; COFF: @__profc_foo_extern = linkonce_odr hidden global {{.*}}section ".lprfc$M", comdat, align 8
+; COFF: @__profd_foo_extern = linkonce_odr hidden global {{.*}}section ".lprfd$M", comdat, align 8
 define available_externally void @foo_extern() {
   call void @llvm.instrprof.increment(i8* getelementptr inbounds ([10 x i8], [10 x i8]* @__profn_foo_extern, i32 0, i32 0), i64 0, i32 1, i32 0)
   ret void