[BOLT][DWARF] Add test for DW_AT_ranges input without function output (#81794)

Added a test that relies on -fbasic-block-sections=all and --gc-sections
that exercises a code path that previously printed a warning.

Author: ayermolo

bolt/lib/Rewrite/DWARFRewriter.cpp

@@ -919,15 +919,10 @@ void DWARFRewriter::updateUnitDebugInfo(
       DIEValue LowPCVal = Die->findAttribute(dwarf::DW_AT_low_pc);
       DIEValue HighPCVal = Die->findAttribute(dwarf::DW_AT_high_pc);
       if (FunctionRanges.empty()) {
-        if (LowPCVal && HighPCVal) {
+        if (LowPCVal && HighPCVal)
           FunctionRanges.push_back({0, HighPCVal.getDIEInteger().getValue()});
-        } else {
-          // I haven't seen this case, but who knows what other compilers
-          // generate.
+        else
           FunctionRanges.push_back({0, 1});
-          errs() << "BOLT-WARNING: [internal-dwarf-error]: subprogram got GCed "
-                    "by the linker, DW_AT_ranges is used\n";
-        }
       }
 
       if (FunctionRanges.size() == 1 && !opts::AlwaysConvertToRanges) {

bolt/test/X86/dwarf4-subprogram-single-gc-ranges.test

@@ -2,14 +2,12 @@
 
 # RUN: llvm-mc -dwarf-version=4 -filetype=obj -triple x86_64-unknown-linux %p/Inputs/dwarf4-subprogram-single-gc-ranges-main.s -o %t1.o
 # RUN: %clang %cflags %t1.o -o %t.exe -Wl,-q
-# RUN: llvm-bolt %t.exe -o %t.bolt --update-debug-sections &> %t1.txt
-# RUN: llvm-dwarfdump --show-form --verbose --debug-info %t.bolt >> %t1.txt
+# RUN: llvm-bolt %t.exe -o %t.bolt --update-debug-sections
+# RUN: llvm-dwarfdump --show-form --verbose --debug-info %t.bolt > %t1.txt
 # RUN: cat %t1.txt | FileCheck --check-prefix=POSTCHECK %s
 
 # This test checks BOLT correctly handles DW_TAG_subprogram with Ranges with single entry, when function was GCed.
 
-# POSTCHECK: BOLT-WARNING: [internal-dwarf-error]: subprogram got GCed by the linker, DW_AT_ranges is used
-
 # POSTCHECK: DW_TAG_subprogram
 # POSTCHECK-NEXT: DW_AT_frame_base
 # POSTCHECK-NEXT: DW_AT_linkage_name