[CGData] Fix assertions when skipping name (#151570)

This fixes assertion failures when using
`-indexed-codegen-data-read-function-map-names=false`

Author: kyulee-com

llvm/lib/CGData/StableFunctionMapRecord.cpp

@@ -160,14 +160,18 @@ void StableFunctionMapRecord::deserialize(const unsigned char *&Ptr,
   for (unsigned I = 0; I < NumFuncs; ++I) {
     auto Hash =
         endian::readNext<stable_hash, endianness::little, unaligned>(Ptr);
-    auto FunctionNameId =
+    [[maybe_unused]] auto FunctionNameId =
         endian::readNext<uint32_t, endianness::little, unaligned>(Ptr);
-    assert(FunctionMap->getNameForId(FunctionNameId) &&
-           "FunctionNameId out of range");
-    auto ModuleNameId =
+    [[maybe_unused]] auto ModuleNameId =
         endian::readNext<uint32_t, endianness::little, unaligned>(Ptr);
-    assert(FunctionMap->getNameForId(ModuleNameId) &&
-           "ModuleNameId out of range");
+    // Only validate IDs if we've read the names
+    if (ReadStableFunctionMapNames) {
+      assert(FunctionMap->getNameForId(FunctionNameId) &&
+             "FunctionNameId out of range");
+      assert(FunctionMap->getNameForId(ModuleNameId) &&
+             "ModuleNameId out of range");
+    }
+
     auto InstCount =
         endian::readNext<uint32_t, endianness::little, unaligned>(Ptr);
 

llvm/test/ThinLTO/AArch64/cgdata-merge-read.ll

@@ -30,6 +30,20 @@
 ; RUN: llvm-objdump -d %tout-read.1 | FileCheck %s --check-prefix=THUNK1
 ; RUN: llvm-objdump -d %tout-read.2 | FileCheck %s --check-prefix=THUNK2
 
+; It runs the same if we use -indexed-codegen-data-read-function-map-names=false.
+; RUN: llvm-lto2 run -enable-global-merge-func=true \
+; RUN:    -indexed-codegen-data-read-function-map-names=false \
+; RUN:    -codegen-data-use-path=%tout.cgdata \
+; RUN:    %t-foo.bc %t-goo.bc -o %tout-read \
+; RUN:    -r %t-foo.bc,_f1,px \
+; RUN:    -r %t-goo.bc,_f2,px \
+; RUN:    -r %t-foo.bc,_g,l -r %t-foo.bc,_g1,l -r %t-foo.bc,_g2,l \
+; RUN:    -r %t-goo.bc,_g,l -r %t-goo.bc,_g1,l -r %t-goo.bc,_g2,l
+; RUN: llvm-nm %tout-read.1 | FileCheck %s --check-prefix=READ1
+; RUN: llvm-nm %tout-read.2 | FileCheck %s --check-prefix=READ2
+; RUN: llvm-objdump -d %tout-read.1 | FileCheck %s --check-prefix=THUNK1
+; RUN: llvm-objdump -d %tout-read.2 | FileCheck %s --check-prefix=THUNK2
+
 ; READ1: _f1.Tgm
 ; READ2: _f2.Tgm