[llvm-readobj] - Allow dumping partially corrupted SHT_LLVM_CALL_GRAPH_PROFILE sections.

The code we have currently reports an error if something is not right with the
profile section. Instead we can report a warning and continue dumping when it is possible.
This patch does it.

Differential revision: https://reviews.llvm.org/D83129

llvm/test/tools/llvm-readobj/ELF/call-graph-profile.test

@@ -37,6 +37,69 @@ Sections:
       - From:   bar
         To:     foo
         Weight: 98
+## 0x10 is the normal entry size for the SHT_LLVM_CALL_GRAPH_PROFILE section.
+    EntSize: [[ENTSIZE=0x10]]
 Symbols:
   - Name: foo
   - Name: bar
+
+## Check we report a warning when unable to get the content of the SHT_LLVM_CALL_GRAPH_PROFILE section.
+# RUN: yaml2obj %s -DENTSIZE=0xF -o %t2.o
+# RUN: llvm-readobj %t2.o --cg-profile 2>&1 | FileCheck %s -DFILE=%t2.o --check-prefix=LLVM-ERR
+# RUN: llvm-readelf %t2.o --cg-profile | FileCheck %s --check-prefix=GNU
+
+# LLVM-ERR:      CGProfile [
+# LLVM-ERR-NEXT: warning: '[[FILE]]': unable to dump the SHT_LLVM_CALL_GRAPH_PROFILE section: section [index 1] has an invalid sh_entsize: 15
+# LLVM-ERR-NEXT: ]
+
+## Check we report a warning when unable to dump a name of a symbol.
+# RUN: yaml2obj %s --docnum=2 -o %t3.o
+# RUN: llvm-readobj %t3.o --cg-profile 2>&1 | FileCheck %s -DFILE=%t3.o --check-prefix=LLVM-BROKEN-SYM
+# RUN: llvm-readelf %t3.o --cg-profile | FileCheck %s --check-prefix=GNU
+
+# LLVM-BROKEN-SYM:      CGProfile [
+# LLVM-BROKEN-SYM-NEXT:   CGProfileEntry {
+# LLVM-BROKEN-SYM-NEXT:     From: A (1)
+# LLVM-BROKEN-SYM-NEXT: warning: '[[FILE]]': unable to read the name of symbol with index 2: st_name (0xff) is past the end of the string table of size 0x5
+# LLVM-BROKEN-SYM-NEXT:     To: <?> (2)
+# LLVM-BROKEN-SYM-NEXT:     Weight: 10
+# LLVM-BROKEN-SYM-NEXT:   }
+# LLVM-BROKEN-SYM-NEXT:   CGProfileEntry {
+# LLVM-BROKEN-SYM-NEXT:     From: <?> (2)
+# LLVM-BROKEN-SYM-NEXT:     To: B (3)
+# LLVM-BROKEN-SYM-NEXT:     Weight: 20
+# LLVM-BROKEN-SYM-NEXT:   }
+# LLVM-BROKEN-SYM-NEXT:   CGProfileEntry {
+# LLVM-BROKEN-SYM-NEXT:     From: (0)
+# LLVM-BROKEN-SYM-NEXT: warning: '[[FILE]]': unable to read the name of symbol with index 4: unable to get symbol from section [index 3]: invalid symbol index (4)
+# LLVM-BROKEN-SYM-NEXT:     To: <?> (4)
+# LLVM-BROKEN-SYM-NEXT:     Weight: 20
+# LLVM-BROKEN-SYM-NEXT:   }
+# LLVM-BROKEN-SYM-NEXT: ]
+
+--- !ELF
+FileHeader:
+  Class:   ELFCLASS64
+  Data:    ELFDATA2LSB
+  Type:    ET_DYN
+  Machine: EM_X86_64
+Sections:
+  - Name: .llvm.call-graph-profile
+    Type: SHT_LLVM_CALL_GRAPH_PROFILE
+    Entries:
+      - From:   1
+        To:     2
+        Weight: 10
+      - From:   2
+        To:     3
+        Weight: 20
+      - From:   0x0 ## Null symbol.
+        To:     0x4 ## This index goes past the end of the symbol table.
+        Weight: 20
+  - Name:    .strtab
+    Type:    SHT_STRTAB
+    Content: "0041004200" ## '\0', 'A', '\0', 'B', '\0'
+Symbols:
+  - StName: 1    ## 'A'
+  - StName: 0xFF ## An arbitrary currupted index in the string table.
+  - StName: 3    ## 'B'

llvm/tools/llvm-readobj/ELFDumper.cpp

@@ -6564,21 +6564,32 @@ void LLVMStyle<ELFT>::printCGProfile(const ELFFile<ELFT> *Obj) {
   ListScope L(W, "CGProfile");
   if (!this->dumper()->getDotCGProfileSec())
     return;
-  auto CGProfile = unwrapOrError(
-      this->FileName, Obj->template getSectionContentsAsArray<Elf_CGProfile>(
-                          this->dumper()->getDotCGProfileSec()));
-  for (const Elf_CGProfile &CGPE : CGProfile) {
+
+  Expected<ArrayRef<Elf_CGProfile>> CGProfileOrErr =
+      Obj->template getSectionContentsAsArray<Elf_CGProfile>(
+          this->dumper()->getDotCGProfileSec());
+  if (!CGProfileOrErr) {
+    this->reportUniqueWarning(
+        createError("unable to dump the SHT_LLVM_CALL_GRAPH_PROFILE section: " +
+                    toString(CGProfileOrErr.takeError())));
+    return;
+  }
+
+  auto GetSymName = [&](uint32_t Index) -> std::string {
+    if (Expected<std::string> NameOrErr =
+            this->dumper()->getStaticSymbolName(Index))
+      return *NameOrErr;
+    else
+      this->reportUniqueWarning(
+          createError("unable to read the name of symbol with index " +
+                      Twine(Index) + ": " + toString(NameOrErr.takeError())));
+    return "<?>";
+  };
+
+  for (const Elf_CGProfile &CGPE : *CGProfileOrErr) {
     DictScope D(W, "CGProfileEntry");
-    W.printNumber(
-        "From",
-        unwrapOrError(this->FileName,
-                      this->dumper()->getStaticSymbolName(CGPE.cgp_from)),
-        CGPE.cgp_from);
-    W.printNumber(
-        "To",
-        unwrapOrError(this->FileName,
-                      this->dumper()->getStaticSymbolName(CGPE.cgp_to)),
-        CGPE.cgp_to);
+    W.printNumber("From", GetSymName(CGPE.cgp_from), CGPE.cgp_from);
+    W.printNumber("To", GetSymName(CGPE.cgp_to), CGPE.cgp_to);
     W.printNumber("Weight", CGPE.cgp_weight);
   }
 }