Reverting PR #184065 and #200323 to address some interplay with CFI (#201194)

There is a relation between CFI and ThinLTO GUIDs that still needs to be
disentangled first. Note that we leave the `MD_unique_id` in
`FixedMetadataKinds.def` to avoid needing to re-number it later. Plus
the metadata string ("guid") itself is used by ctxprof.

Author: mtrofin

clang/lib/CodeGen/CGCUDANV.cpp

@@ -25,7 +25,6 @@
 #include "llvm/IR/BasicBlock.h"
 #include "llvm/IR/Constants.h"
 #include "llvm/IR/DerivedTypes.h"
-#include "llvm/IR/GlobalValue.h"
 #include "llvm/IR/ReplaceConstant.h"
 #include "llvm/Support/Format.h"
 #include "llvm/Support/VirtualFileSystem.h"
@@ -1015,10 +1014,7 @@ llvm::Function *CGNVCUDARuntime::makeModuleCtorFunction() {
     // Generate a unique module ID.
     SmallString<64> ModuleID;
     llvm::raw_svector_ostream OS(ModuleID);
-    OS << ModuleIDPrefix
-       << llvm::format("%" PRIx64,
-                       llvm::GlobalValue::getGUIDAssumingExternalLinkage(
-                           FatbinWrapper->getName()));
+    OS << ModuleIDPrefix << llvm::format("%" PRIx64, FatbinWrapper->getGUID());
     llvm::Constant *ModuleIDConstant = makeConstantArray(
         std::string(ModuleID), "", ModuleIDSectionName, 32, /*AddNull=*/true);
 

clang/test/CodeGen/cfi-icall-trap-recover-runtime.c

@@ -15,32 +15,32 @@
 
 
 // TRAP-LABEL: define hidden void @f(
-// TRAP-SAME: ) #[[ATTR0:[0-9]+]] !type [[META6:![0-9]+]] !type [[META7:![0-9]+]]
+// TRAP-SAME: ) #[[ATTR0:[0-9]+]] !type [[META6:![0-9]+]] !type [[META7:![0-9]+]] {
 // TRAP-NEXT:  [[ENTRY:.*:]]
 // TRAP-NEXT:    ret void
 //
 // ABORT-LABEL: define hidden void @f(
-// ABORT-SAME: ) #[[ATTR0:[0-9]+]] !type [[META6:![0-9]+]] !type [[META7:![0-9]+]]
+// ABORT-SAME: ) #[[ATTR0:[0-9]+]] !type [[META6:![0-9]+]] !type [[META7:![0-9]+]] {
 // ABORT-NEXT:  [[ENTRY:.*:]]
 // ABORT-NEXT:    ret void
 //
 // RECOVER-LABEL: define hidden void @f(
-// RECOVER-SAME: ) #[[ATTR0:[0-9]+]] !type [[META6:![0-9]+]] !type [[META7:![0-9]+]]
+// RECOVER-SAME: ) #[[ATTR0:[0-9]+]] !type [[META6:![0-9]+]] !type [[META7:![0-9]+]] {
 // RECOVER-NEXT:  [[ENTRY:.*:]]
 // RECOVER-NEXT:    ret void
 //
 // ABORT_MIN-LABEL: define hidden void @f(
-// ABORT_MIN-SAME: ) #[[ATTR0:[0-9]+]] !type [[META6:![0-9]+]] !type [[META7:![0-9]+]]
+// ABORT_MIN-SAME: ) #[[ATTR0:[0-9]+]] !type [[META6:![0-9]+]] !type [[META7:![0-9]+]] {
 // ABORT_MIN-NEXT:  [[ENTRY:.*:]]
 // ABORT_MIN-NEXT:    ret void
 //
 // RECOVER_MIN-LABEL: define hidden void @f(
-// RECOVER_MIN-SAME: ) #[[ATTR0:[0-9]+]] !type [[META6:![0-9]+]] !type [[META7:![0-9]+]]
+// RECOVER_MIN-SAME: ) #[[ATTR0:[0-9]+]] !type [[META6:![0-9]+]] !type [[META7:![0-9]+]] {
 // RECOVER_MIN-NEXT:  [[ENTRY:.*:]]
 // RECOVER_MIN-NEXT:    ret void
 //
 // PRESERVE_MIN-LABEL: define hidden void @f(
-// PRESERVE_MIN-SAME: ) #[[ATTR0:[0-9]+]] !type [[META6:![0-9]+]] !type [[META7:![0-9]+]]
+// PRESERVE_MIN-SAME: ) #[[ATTR0:[0-9]+]] !type [[META6:![0-9]+]] !type [[META7:![0-9]+]] {
 // PRESERVE_MIN-NEXT:  [[ENTRY:.*:]]
 // PRESERVE_MIN-NEXT:    ret void
 //
@@ -50,7 +50,7 @@ void f() {
 void xf();
 
 // TRAP-LABEL: define hidden void @g(
-// TRAP-SAME: i32 noundef [[B:%.*]]) #[[ATTR0]] !type [[META8:![0-9]+]] !type [[META9:![0-9]+]]
+// TRAP-SAME: i32 noundef [[B:%.*]]) #[[ATTR0]] !type [[META8:![0-9]+]] !type [[META9:![0-9]+]] {
 // TRAP-NEXT:  [[ENTRY:.*:]]
 // TRAP-NEXT:    [[B_ADDR:%.*]] = alloca i32, align 4
 // TRAP-NEXT:    [[FP:%.*]] = alloca ptr, align 8
@@ -71,7 +71,7 @@ void xf();
 // TRAP-NEXT:    ret void
 //
 // ABORT-LABEL: define hidden void @g(
-// ABORT-SAME: i32 noundef [[B:%.*]]) #[[ATTR0]] !type [[META8:![0-9]+]] !type [[META9:![0-9]+]]
+// ABORT-SAME: i32 noundef [[B:%.*]]) #[[ATTR0]] !type [[META8:![0-9]+]] !type [[META9:![0-9]+]] {
 // ABORT-NEXT:  [[ENTRY:.*:]]
 // ABORT-NEXT:    [[B_ADDR:%.*]] = alloca i32, align 4
 // ABORT-NEXT:    [[FP:%.*]] = alloca ptr, align 8
@@ -93,7 +93,7 @@ void xf();
 // ABORT-NEXT:    ret void
 //
 // RECOVER-LABEL: define hidden void @g(
-// RECOVER-SAME: i32 noundef [[B:%.*]]) #[[ATTR0]] !type [[META8:![0-9]+]] !type [[META9:![0-9]+]]
+// RECOVER-SAME: i32 noundef [[B:%.*]]) #[[ATTR0]] !type [[META8:![0-9]+]] !type [[META9:![0-9]+]] {
 // RECOVER-NEXT:  [[ENTRY:.*:]]
 // RECOVER-NEXT:    [[B_ADDR:%.*]] = alloca i32, align 4
 // RECOVER-NEXT:    [[FP:%.*]] = alloca ptr, align 8
@@ -115,7 +115,7 @@ void xf();
 // RECOVER-NEXT:    ret void
 //
 // ABORT_MIN-LABEL: define hidden void @g(
-// ABORT_MIN-SAME: i32 noundef [[B:%.*]]) #[[ATTR0]] !type [[META8:![0-9]+]] !type [[META9:![0-9]+]]
+// ABORT_MIN-SAME: i32 noundef [[B:%.*]]) #[[ATTR0]] !type [[META8:![0-9]+]] !type [[META9:![0-9]+]] {
 // ABORT_MIN-NEXT:  [[ENTRY:.*:]]
 // ABORT_MIN-NEXT:    [[B_ADDR:%.*]] = alloca i32, align 4
 // ABORT_MIN-NEXT:    [[FP:%.*]] = alloca ptr, align 8
@@ -136,7 +136,7 @@ void xf();
 // ABORT_MIN-NEXT:    ret void
 //
 // RECOVER_MIN-LABEL: define hidden void @g(
-// RECOVER_MIN-SAME: i32 noundef [[B:%.*]]) #[[ATTR0]] !type [[META8:![0-9]+]] !type [[META9:![0-9]+]]
+// RECOVER_MIN-SAME: i32 noundef [[B:%.*]]) #[[ATTR0]] !type [[META8:![0-9]+]] !type [[META9:![0-9]+]] {
 // RECOVER_MIN-NEXT:  [[ENTRY:.*:]]
 // RECOVER_MIN-NEXT:    [[B_ADDR:%.*]] = alloca i32, align 4
 // RECOVER_MIN-NEXT:    [[FP:%.*]] = alloca ptr, align 8
@@ -157,7 +157,7 @@ void xf();
 // RECOVER_MIN-NEXT:    ret void
 //
 // PRESERVE_MIN-LABEL: define hidden void @g(
-// PRESERVE_MIN-SAME: i32 noundef [[B:%.*]]) #[[ATTR0]] !type [[META8:![0-9]+]] !type [[META9:![0-9]+]]
+// PRESERVE_MIN-SAME: i32 noundef [[B:%.*]]) #[[ATTR0]] !type [[META8:![0-9]+]] !type [[META9:![0-9]+]] {
 // PRESERVE_MIN-NEXT:  [[ENTRY:.*:]]
 // PRESERVE_MIN-NEXT:    [[B_ADDR:%.*]] = alloca i32, align 4
 // PRESERVE_MIN-NEXT:    [[FP:%.*]] = alloca ptr, align 8

clang/test/CodeGen/lto-newpm-pipeline.c

@@ -34,7 +34,6 @@
 // CHECK-FULL-O0-NEXT: Running pass: CoroConditionalWrapper
 // CHECK-FULL-O0-NEXT: Running pass: CanonicalizeAliasesPass
 // CHECK-FULL-O0-NEXT: Running pass: NameAnonGlobalPass
-// CHECK-FULL-O0-NEXT: Running pass: AssignGUIDPass
 // CHECK-FULL-O0-NEXT: Running pass: AnnotationRemarksPass
 // CHECK-FULL-O0-NEXT: Running analysis: TargetLibraryAnalysis
 // CHECK-FULL-O0-NEXT: Running pass: VerifierPass
@@ -49,7 +48,6 @@
 // CHECK-THIN-O0-NEXT: Running pass: CoroConditionalWrapper
 // CHECK-THIN-O0-NEXT: Running pass: CanonicalizeAliasesPass
 // CHECK-THIN-O0-NEXT: Running pass: NameAnonGlobalPass
-// CHECK-THIN-O0-NEXT: Running pass: AssignGUIDPass
 // CHECK-THIN-O0-NEXT: Running pass: AnnotationRemarksPass
 // CHECK-THIN-O0-NEXT: Running analysis: TargetLibraryAnalysis
 // CHECK-THIN-O0-NEXT: Running pass: VerifierPass
@@ -66,7 +64,6 @@
 // CHECK-THIN-OPTIMIZED-NOT: Running pass: LoopVectorizePass
 // CHECK-THIN-OPTIMIZED: Running pass: CanonicalizeAliasesPass
 // CHECK-THIN-OPTIMIZED: Running pass: NameAnonGlobalPass
-// CHECK-THIN-OPTIMIZED: Running pass: AssignGUIDPass
 // CHECK-THIN-OPTIMIZED: Running pass: ThinLTOBitcodeWriterPass
 
 void Foo(void) {}

clang/test/CodeGenCXX/cfi-vcall-trap-recover-runtime.cpp

@@ -19,7 +19,7 @@ struct S1 {
 };
 
 // TRAP-LABEL: define hidden void @_Z3s1fP2S1(
-// TRAP-SAME: ptr noundef [[S1:%.*]]) #[[ATTR0:[0-9]+]]
+// TRAP-SAME: ptr noundef [[S1:%.*]]) #[[ATTR0:[0-9]+]] {
 // TRAP-NEXT:  [[ENTRY:.*:]]
 // TRAP-NEXT:    [[S1_ADDR:%.*]] = alloca ptr, align 8
 // TRAP-NEXT:    store ptr [[S1]], ptr [[S1_ADDR]], align 8
@@ -37,7 +37,7 @@ struct S1 {
 // TRAP-NEXT:    ret void
 //
 // ABORT-LABEL: define hidden void @_Z3s1fP2S1(
-// ABORT-SAME: ptr noundef [[S1:%.*]]) #[[ATTR0:[0-9]+]]
+// ABORT-SAME: ptr noundef [[S1:%.*]]) #[[ATTR0:[0-9]+]] {
 // ABORT-NEXT:  [[ENTRY:.*:]]
 // ABORT-NEXT:    [[S1_ADDR:%.*]] = alloca ptr, align 8
 // ABORT-NEXT:    store ptr [[S1]], ptr [[S1_ADDR]], align 8
@@ -58,7 +58,7 @@ struct S1 {
 // ABORT-NEXT:    ret void
 //
 // RECOVER-LABEL: define hidden void @_Z3s1fP2S1(
-// RECOVER-SAME: ptr noundef [[S1:%.*]]) #[[ATTR0:[0-9]+]]
+// RECOVER-SAME: ptr noundef [[S1:%.*]]) #[[ATTR0:[0-9]+]] {
 // RECOVER-NEXT:  [[ENTRY:.*:]]
 // RECOVER-NEXT:    [[S1_ADDR:%.*]] = alloca ptr, align 8
 // RECOVER-NEXT:    store ptr [[S1]], ptr [[S1_ADDR]], align 8
@@ -79,7 +79,7 @@ struct S1 {
 // RECOVER-NEXT:    ret void
 //
 // ABORT_MIN-LABEL: define hidden void @_Z3s1fP2S1(
-// ABORT_MIN-SAME: ptr noundef [[S1:%.*]]) #[[ATTR0:[0-9]+]]
+// ABORT_MIN-SAME: ptr noundef [[S1:%.*]]) #[[ATTR0:[0-9]+]] {
 // ABORT_MIN-NEXT:  [[ENTRY:.*:]]
 // ABORT_MIN-NEXT:    [[S1_ADDR:%.*]] = alloca ptr, align 8
 // ABORT_MIN-NEXT:    store ptr [[S1]], ptr [[S1_ADDR]], align 8
@@ -98,7 +98,7 @@ struct S1 {
 // ABORT_MIN-NEXT:    ret void
 //
 // RECOVER_MIN-LABEL: define hidden void @_Z3s1fP2S1(
-// RECOVER_MIN-SAME: ptr noundef [[S1:%.*]]) #[[ATTR0:[0-9]+]]
+// RECOVER_MIN-SAME: ptr noundef [[S1:%.*]]) #[[ATTR0:[0-9]+]] {
 // RECOVER_MIN-NEXT:  [[ENTRY:.*:]]
 // RECOVER_MIN-NEXT:    [[S1_ADDR:%.*]] = alloca ptr, align 8
 // RECOVER_MIN-NEXT:    store ptr [[S1]], ptr [[S1_ADDR]], align 8
@@ -117,7 +117,7 @@ struct S1 {
 // RECOVER_MIN-NEXT:    ret void
 //
 // PRESERVE_MIN-LABEL: define hidden void @_Z3s1fP2S1(
-// PRESERVE_MIN-SAME: ptr noundef [[S1:%.*]]) #[[ATTR0:[0-9]+]]
+// PRESERVE_MIN-SAME: ptr noundef [[S1:%.*]]) #[[ATTR0:[0-9]+]] {
 // PRESERVE_MIN-NEXT:  [[ENTRY:.*:]]
 // PRESERVE_MIN-NEXT:    [[S1_ADDR:%.*]] = alloca ptr, align 8
 // PRESERVE_MIN-NEXT:    store ptr [[S1]], ptr [[S1_ADDR]], align 8

lld/test/ELF/lto/devirt_vcall_vis_export_dynamic.ll

@@ -5,7 +5,7 @@
 
 ;; Index based WPD
 ;; Generate unsplit module with summary for ThinLTO index-based WPD.
-; RUN: opt --passes=assign-guid --thinlto-bc -o %t2.o %s
+; RUN: opt --thinlto-bc -o %t2.o %s
 ; RUN: ld.lld %t2.o -o %t3 -save-temps --lto-whole-program-visibility \
 ; RUN:   -mllvm -pass-remarks=. 2>&1 | FileCheck %s --check-prefix=REMARK
 ; RUN: llvm-dis %t2.o.4.opt.bc -o - | FileCheck %s --check-prefix=CHECK-IR
@@ -16,13 +16,13 @@
 
 ;; Hybrid WPD
 ;; Generate split module with summary for hybrid Thin/Regular LTO WPD.
-; RUN: opt --passes=assign-guid --thinlto-bc --thinlto-split-lto-unit -o %t.o %s
+; RUN: opt --thinlto-bc --thinlto-split-lto-unit -o %t.o %s
 ; RUN: ld.lld %t.o -o %t3 -save-temps --lto-whole-program-visibility \
 ; RUN:   -mllvm -pass-remarks=. 2>&1 | FileCheck %s --check-prefix=REMARK
 ; RUN: llvm-dis %t.o.4.opt.bc -o - | FileCheck %s --check-prefix=CHECK-IR
 
 ;; Regular LTO WPD
-; RUN: opt --passes=assign-guid -o %t4.o %s
+; RUN: opt -o %t4.o %s
 ; RUN: ld.lld %t4.o -o %t3 -save-temps --lto-whole-program-visibility \
 ; RUN:   -mllvm -pass-remarks=. 2>&1 | FileCheck %s --check-prefix=REMARK
 ; RUN: llvm-dis %t3.0.4.opt.bc -o - | FileCheck %s --check-prefix=CHECK-IR
@@ -107,19 +107,19 @@
 ;; preemption, even without any options.
 
 ;; Index based WPD
-; RUN: opt --passes=assign-guid -relocation-model=pic --thinlto-bc -o %t5.o %s
+; RUN: opt -relocation-model=pic --thinlto-bc -o %t5.o %s
 ; RUN: ld.lld %t5.o -o %t5.so -shared
 ; RUN: ld.lld %t5.o %t5.so -o %t5 -save-temps --lto-whole-program-visibility \
 ; RUN:   -mllvm -pass-remarks=. 2>&1 | FileCheck /dev/null --implicit-check-not single-impl --allow-empty
 
 ;; Hybrid WPD
-; RUN: opt --passes=assign-guid -relocation-model=pic --thinlto-bc --thinlto-split-lto-unit -o %t5.o %s
+; RUN: opt -relocation-model=pic --thinlto-bc --thinlto-split-lto-unit -o %t5.o %s
 ; RUN: ld.lld %t5.o -o %t5.so -shared
 ; RUN: ld.lld %t5.o %t5.so -o %t5 -save-temps --lto-whole-program-visibility \
 ; RUN:   -mllvm -pass-remarks=. 2>&1 | FileCheck /dev/null --implicit-check-not single-impl --allow-empty
 
 ;; Regular LTO WPD
-; RUN: opt --passes=assign-guid -relocation-model=pic -o %t5.o %s
+; RUN: opt -relocation-model=pic -o %t5.o %s
 ; RUN: ld.lld %t5.o -o %t5.so -shared
 ; RUN: ld.lld %t5.o %t5.so -o %t5 -save-temps --lto-whole-program-visibility \
 ; RUN:   -mllvm -pass-remarks=. 2>&1 | FileCheck /dev/null --implicit-check-not single-impl --allow-empty

lld/test/ELF/lto/devirt_vcall_vis_public.ll

@@ -3,20 +3,20 @@
 
 ;; Index based WPD
 ;; Generate unsplit module with summary for ThinLTO index-based WPD.
-; RUN: opt --passes=assign-guid --thinlto-bc -o %t2.o %s
+; RUN: opt --thinlto-bc -o %t2.o %s
 ; RUN: ld.lld %t2.o -o %t3 -save-temps --lto-whole-program-visibility \
 ; RUN:   -mllvm -pass-remarks=. 2>&1 | FileCheck %s --check-prefix=REMARK
 ; RUN: llvm-dis %t2.o.4.opt.bc -o - | FileCheck %s --check-prefix=CHECK-IR
 
 ;; Hybrid WPD
 ;; Generate split module with summary for hybrid Thin/Regular LTO WPD.
-; RUN: opt --passes=assign-guid --thinlto-bc --thinlto-split-lto-unit -o %t.o %s
+; RUN: opt --thinlto-bc --thinlto-split-lto-unit -o %t.o %s
 ; RUN: ld.lld %t.o -o %t3 -save-temps --lto-whole-program-visibility \
 ; RUN:   -mllvm -pass-remarks=. 2>&1 | FileCheck %s --check-prefix=REMARK
 ; RUN: llvm-dis %t.o.4.opt.bc -o - | FileCheck %s --check-prefix=CHECK-IR
 
 ;; Regular LTO WPD
-; RUN: opt --passes=assign-guid -o %t4.o %s
+; RUN: opt -o %t4.o %s
 ; RUN: ld.lld %t4.o -o %t3 -save-temps --lto-whole-program-visibility \
 ; RUN:   -mllvm -pass-remarks=. 2>&1 | FileCheck %s --check-prefix=REMARK
 ; RUN: llvm-dis %t3.0.4.opt.bc -o - | FileCheck %s --check-prefix=CHECK-IR

lld/test/ELF/lto/devirt_vcall_vis_shared_def.ll

@@ -6,23 +6,23 @@
 
 ;; Index based WPD
 ;; Generate unsplit module with summary for ThinLTO index-based WPD.
-; RUN: opt --passes=assign-guid --thinlto-bc -o %t1a.o %s
-; RUN: opt --passes=assign-guid --thinlto-bc -o %t2a.o %S/Inputs/devirt_vcall_vis_shared_def.ll
+; RUN: opt --thinlto-bc -o %t1a.o %s
+; RUN: opt --thinlto-bc -o %t2a.o %S/Inputs/devirt_vcall_vis_shared_def.ll
 ; RUN: ld.lld %t1a.o %t2a.o -o %t3a -save-temps --lto-whole-program-visibility \
 ; RUN:   -mllvm -pass-remarks=. 2>&1 | FileCheck %s --check-prefix=REMARK
 ; RUN: llvm-dis %t1a.o.4.opt.bc -o - | FileCheck %s --check-prefix=CHECK-IR
 
 ;; Hybrid WPD
 ;; Generate split module with summary for hybrid Thin/Regular LTO WPD.
-; RUN: opt --passes=assign-guid --thinlto-bc --thinlto-split-lto-unit -o %t1b.o %s
-; RUN: opt --passes=assign-guid --thinlto-bc --thinlto-split-lto-unit -o %t2b.o %S/Inputs/devirt_vcall_vis_shared_def.ll
+; RUN: opt --thinlto-bc --thinlto-split-lto-unit -o %t1b.o %s
+; RUN: opt --thinlto-bc --thinlto-split-lto-unit -o %t2b.o %S/Inputs/devirt_vcall_vis_shared_def.ll
 ; RUN: ld.lld %t1b.o %t2b.o -o %t3b -save-temps --lto-whole-program-visibility \
 ; RUN:   -mllvm -pass-remarks=. 2>&1 | FileCheck %s --check-prefix=REMARK
 ; RUN: llvm-dis %t1b.o.4.opt.bc -o - | FileCheck %s --check-prefix=CHECK-IR
 
 ;; Regular LTO WPD
-; RUN: opt --passes=assign-guid -o %t1c.o %s
-; RUN: opt --passes=assign-guid -o %t2c.o %S/Inputs/devirt_vcall_vis_shared_def.ll
+; RUN: opt -o %t1c.o %s
+; RUN: opt -o %t2c.o %S/Inputs/devirt_vcall_vis_shared_def.ll
 ; RUN: ld.lld %t1c.o %t2c.o -o %t3c -save-temps --lto-whole-program-visibility \
 ; RUN:   -mllvm -pass-remarks=. 2>&1 | FileCheck %s --check-prefix=REMARK
 ; RUN: llvm-dis %t3c.0.4.opt.bc -o - | FileCheck %s --check-prefix=CHECK-IR

llvm/include/llvm/Analysis/CtxProfAnalysis.h

@@ -47,6 +47,9 @@ class PGOContextualProfile {
   // we'll need when we maintain the profiles during IPO transformations.
   std::map<GlobalValue::GUID, FunctionInfo> FuncInfo;
 
+  /// Get the GUID of this Function if it's defined in this module.
+  LLVM_ABI GlobalValue::GUID getDefinedFunctionGUID(const Function &F) const;
+
   // This is meant to be constructed from CtxProfAnalysis, which will also set
   // its state piecemeal.
   PGOContextualProfile() = default;
@@ -65,7 +68,9 @@ class PGOContextualProfile {
 
   LLVM_ABI bool isInSpecializedModule() const;
 
-  bool isFunctionKnown(const Function &F) const { return !F.isDeclaration(); }
+  bool isFunctionKnown(const Function &F) const {
+    return getDefinedFunctionGUID(F) != 0;
+  }
 
   StringRef getFunctionName(GlobalValue::GUID GUID) const {
     auto It = FuncInfo.find(GUID);
@@ -76,22 +81,22 @@ class PGOContextualProfile {
 
   uint32_t getNumCounters(const Function &F) const {
     assert(isFunctionKnown(F));
-    return FuncInfo.find(F.getGUID())->second.NextCounterIndex;
+    return FuncInfo.find(getDefinedFunctionGUID(F))->second.NextCounterIndex;
   }
 
   uint32_t getNumCallsites(const Function &F) const {
     assert(isFunctionKnown(F));
-    return FuncInfo.find(F.getGUID())->second.NextCallsiteIndex;
+    return FuncInfo.find(getDefinedFunctionGUID(F))->second.NextCallsiteIndex;
   }
 
   uint32_t allocateNextCounterIndex(const Function &F) {
     assert(isFunctionKnown(F));
-    return FuncInfo.find(F.getGUID())->second.NextCounterIndex++;
+    return FuncInfo.find(getDefinedFunctionGUID(F))->second.NextCounterIndex++;
   }
 
   uint32_t allocateNextCallsiteIndex(const Function &F) {
     assert(isFunctionKnown(F));
-    return FuncInfo.find(F.getGUID())->second.NextCallsiteIndex++;
+    return FuncInfo.find(getDefinedFunctionGUID(F))->second.NextCallsiteIndex++;
   }
 
   using ConstVisitor = function_ref<void(const PGOCtxProfContext &)>;
@@ -182,5 +187,26 @@ class ProfileAnnotator {
   LLVM_ABI ~ProfileAnnotator();
 };
 
+/// Assign a GUID to functions as metadata. GUID calculation takes linkage into
+/// account, which may change especially through and after thinlto. By
+/// pre-computing and assigning as metadata, this mechanism is resilient to such
+/// changes (as well as name changes e.g. suffix ".llvm." additions).
+
+// FIXME(mtrofin): we can generalize this mechanism to calculate a GUID early in
+// the pass pipeline, associate it with any Global Value, and then use it for
+// PGO and ThinLTO.
+// At that point, this should be moved elsewhere.
+class AssignGUIDPass : public OptionalPassInfoMixin<AssignGUIDPass> {
+public:
+  explicit AssignGUIDPass() = default;
+
+  /// Assign a GUID *if* one is not already assign, as a function metadata named
+  /// `GUIDMetadataName`.
+  LLVM_ABI PreservedAnalyses run(Module &M, ModuleAnalysisManager &MAM);
+  LLVM_ABI static const char *GUIDMetadataName;
+  // This should become GlobalValue::getGUID
+  LLVM_ABI static uint64_t getGUID(const Function &F);
+};
+
 } // namespace llvm
 #endif // LLVM_ANALYSIS_CTXPROFANALYSIS_H

llvm/include/llvm/Bitcode/BitcodeReader.h

@@ -17,7 +17,6 @@
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Bitstream/BitCodeEnums.h"
 #include "llvm/IR/GlobalValue.h"
-#include "llvm/IR/ModuleSummaryIndex.h"
 #include "llvm/Support/Compiler.h"
 #include "llvm/Support/Endian.h"
 #include "llvm/Support/Error.h"
@@ -166,8 +165,7 @@ struct ParserCallbacks {
     /// into CombinedIndex.
     LLVM_ABI Error
     readSummary(ModuleSummaryIndex &CombinedIndex, StringRef ModulePath,
-                std::function<bool(StringRef)> IsPrevailing = nullptr,
-                std::function<void(ValueInfo)> OnValueInfo = nullptr);
+                std::function<bool(GlobalValue::GUID)> IsPrevailing = nullptr);
   };
 
   struct BitcodeFileContents {

llvm/include/llvm/Bitcode/LLVMBitCodes.h

@@ -120,9 +120,6 @@ enum ModuleCodes {
 
   // IFUNC: [ifunc value type, addrspace, resolver val#, linkage, visibility]
   MODULE_CODE_IFUNC = 18,
-
-  // GUIDLIST: [n x i64]
-  MODULE_CODE_GUIDLIST = 19,
 };
 
 /// PARAMATTR blocks have code for defining a parameter attribute set.