Failure to build against LLVM-21

I saw that LLLVM-21 support had been added, so I tried building against it. I used the built in script to build LLVM 21 with all targets enabled, this is the diff of what I modified

diff --git a/llvm/Makefile b/llvm/Makefile
index f05c33b..e69d957 100644
--- a/llvm/Makefile
+++ b/llvm/Makefile
@@ -4,14 +4,14 @@
 # PATH.
 
 PWD:=$(shell pwd)
-LLVM_RELEASE=19.1.7
+LLVM_RELEASE=21.1.8
 LLVM_INSTALL_DIR=$(PWD)/install
 LLVM_SRC_DIR=llvm-project-$(LLVM_RELEASE).src
 DL=wget
 LLVM_SRC_FNAME=$(LLVM_SRC_DIR).tar.xz
 LLVM_RELEASE_URL=https://github.com/llvm/llvm-project/releases/download/llvmorg-$(LLVM_RELEASE)
 LLVM_SRC_LINK=$(LLVM_RELEASE_URL)/$(LLVM_SRC_FNAME)
-LLVM_TARGETS=X86
+LLVM_TARGETS=all
 # Linking LLVM libraries and binaries requires lots of RAM and is a common cause
 # for out-of-memory errors. Restricting the build system to a single link job at
 # a time doesn't affect the build time significantly but protects us from those

I followed the build instructions and I cloned the llvm-bindings as indicated but used the llvm-21 branch. LLVM built just fine. However, GNAT-LLVM fails at the very end with the following issue:

⦗OSS CAD Suite⦘ 📦[fernando@tumbleweed gnat-llvm21]$ make -j1
make -C llvm-interface build gnatlib-automated
make[1]: Entering directory '/home/fernando/Build/gnat-llvm21/llvm-interface'
mkdir -p obj obj-tools/libgnat bin gnat_src/vast
for f in `cd /home/fernando/Build/gnat-llvm21/llvm-interface/gnat_src; ls gen_il*.ad? xutil.ad? *-tmpl xoscons.adb xsnamest.adb`; \
do \
  cp -p /home/fernando/Build/gnat-llvm21/llvm-interface/gnat_src/$f obj-tools; \
done
cd obj-tools && gnatmake -q -j0 xoscons xsnamest && ./xsnamest && \
mv -f snames.ns ../obj/snames.ads && mv -f snames.nb ../obj/snames.adb && \
gnatmake -g -q -j0 gen_il-main.adb -I../obj -Ilibgnat && ./gen_il-main && \
mv -f nmake.adb nmake.ads seinfo.ads sinfo-nodes.ads sinfo-nodes.adb einfo-entities.ads einfo-entities.adb ../obj
for f in ../link.c s-pehage.adb s-pehage.ads s-rident.ads s-utf_32.adb s-utf_32.ads gnat.ads g-byorma.adb g-casuti.adb g-casuti.ads g-comlin.adb g-comlin.ads g-ctrl_c.adb g-ctrl_c.ads g-dirope.adb g-dynhta.adb g-dynhta.ads g-graphs.adb g-graphs.ads g-hesora.adb g-htable.adb g-io.adb g-io_aux.adb g-io_aux.ads g-lists.adb g-lists.ads g-os_lib.adb g-os_lib.ads g-regexp.ads g-sets.adb g-sets.ads g-spchge.adb g-speche.adb g-string.ads g-u3spch.adb; do \
  ln -sf /home/fernando/Build/gnat-llvm21/llvm-interface/gnat_src/libgnat/$f obj; \
done
./check_for_LLVM_aliasing_bug.sh
using LLVM with the aliasing bug, will pessimize slightly the optimized code
obj/gnatllvm-aliasing-params.ads is unchanged
./check_for_llvm_apis.sh "/home/fernando/Build/gnat-llvm21/llvm-interface/../llvm/llvm-obj/bin/llvm-config"
obj/gnat-llvm-config.h is unchanged
./configure_default_target.sh "x86_64-suse-linux"
obj/options-target.ads is unchanged
gprbuild -v -n -XLLVM_Version=21 -x -Pgnat_llvm -j0 \
  -largs -L/home/fernando/Build/gnat-llvm21/llvm/llvm-obj/lib  -lLLVMWindowsManifest -lLLVMXRay -lLLVMLibDriver -lLLVMDlltoolDriver -lLLVMTelemetry -lLLVMTextAPIBinaryReader -lLLVMCoverage -lLLVMLineEditor -lLLVMXCoreDisassembler -lLLVMXCoreCodeGen -lLLVMXCoreDesc -lLLVMXCoreInfo -lLLVMX86TargetMCA -lLLVMX86Disassembler -lLLVMX86AsmParser -lLLVMX86CodeGen -lLLVMX86Desc -lLLVMX86Info -lLLVMWebAssemblyDisassembler -lLLVMWebAssemblyAsmParser -lLLVMWebAssemblyCodeGen -lLLVMWebAssemblyUtils -lLLVMWebAssemblyDesc -lLLVMWebAssemblyInfo -lLLVMVEDisassembler -lLLVMVEAsmParser -lLLVMVECodeGen -lLLVMVEDesc -lLLVMVEInfo -lLLVMSystemZDisassembler -lLLVMSystemZAsmParser -lLLVMSystemZCodeGen -lLLVMSystemZDesc -lLLVMSystemZInfo -lLLVMSPIRVCodeGen -lLLVMSPIRVDesc -lLLVMSPIRVInfo -lLLVMSPIRVAnalysis -lLLVMSparcDisassembler -lLLVMSparcAsmParser -lLLVMSparcCodeGen -lLLVMSparcDesc -lLLVMSparcInfo -lLLVMRISCVTargetMCA -lLLVMRISCVDisassembler -lLLVMRISCVAsmParser -lLLVMRISCVCodeGen -lLLVMRISCVDesc -lLLVMRISCVInfo -lLLVMPowerPCDisassembler -lLLVMPowerPCAsmParser -lLLVMPowerPCCodeGen -lLLVMPowerPCDesc -lLLVMPowerPCInfo -lLLVMNVPTXCodeGen -lLLVMNVPTXDesc -lLLVMNVPTXInfo -lLLVMMSP430Disassembler -lLLVMMSP430AsmParser -lLLVMMSP430CodeGen -lLLVMMSP430Desc -lLLVMMSP430Info -lLLVMMipsDisassembler -lLLVMMipsAsmParser -lLLVMMipsCodeGen -lLLVMMipsDesc -lLLVMMipsInfo -lLLVMLoongArchDisassembler -lLLVMLoongArchAsmParser -lLLVMLoongArchCodeGen -lLLVMLoongArchDesc -lLLVMLoongArchInfo -lLLVMLanaiDisassembler -lLLVMLanaiCodeGen -lLLVMLanaiAsmParser -lLLVMLanaiDesc -lLLVMLanaiInfo -lLLVMHexagonDisassembler -lLLVMHexagonCodeGen -lLLVMHexagonAsmParser -lLLVMHexagonDesc -lLLVMHexagonInfo -lLLVMBPFDisassembler -lLLVMBPFAsmParser -lLLVMBPFCodeGen -lLLVMBPFDesc -lLLVMBPFInfo -lLLVMAVRDisassembler -lLLVMAVRAsmParser -lLLVMAVRCodeGen -lLLVMAVRDesc -lLLVMAVRInfo -lLLVMARMDisassembler -lLLVMARMAsmParser -lLLVMARMCodeGen -lLLVMARMDesc -lLLVMARMUtils -lLLVMARMInfo -lLLVMAMDGPUTargetMCA -lLLVMAMDGPUDisassembler -lLLVMAMDGPUAsmParser -lLLVMAMDGPUCodeGen -lLLVMAMDGPUDesc -lLLVMAMDGPUUtils -lLLVMAMDGPUInfo -lLLVMAArch64Disassembler -lLLVMAArch64AsmParser -lLLVMAArch64CodeGen -lLLVMAArch64Desc -lLLVMAArch64Utils -lLLVMAArch64Info -lLLVMOrcDebugging -lLLVMOrcJIT -lLLVMWindowsDriver -lLLVMMCJIT -lLLVMJITLink -lLLVMInterpreter -lLLVMExecutionEngine -lLLVMRuntimeDyld -lLLVMOrcTargetProcess -lLLVMOrcShared -lLLVMDWP -lLLVMDWARFCFIChecker -lLLVMDebugInfoLogicalView -lLLVMOption -lLLVMObjCopy -lLLVMMCA -lLLVMMCDisassembler -lLLVMLTO -lLLVMPasses -lLLVMHipStdPar -lLLVMCFGuard -lLLVMCoroutines -lLLVMipo -lLLVMVectorize -lLLVMSandboxIR -lLLVMLinker -lLLVMFrontendOpenMP -lLLVMFrontendOffloading -lLLVMObjectYAML -lLLVMFrontendOpenACC -lLLVMFrontendHLSL -lLLVMFrontendDriver -lLLVMInstrumentation -lLLVMFrontendDirective -lLLVMFrontendAtomic -lLLVMExtensions -lLLVMDWARFLinkerParallel -lLLVMDWARFLinkerClassic -lLLVMDWARFLinker -lLLVMGlobalISel -lLLVMMIRParser -lLLVMAsmPrinter -lLLVMSelectionDAG -lLLVMCodeGen -lLLVMTarget -lLLVMObjCARCOpts -lLLVMCodeGenTypes -lLLVMCGData -lLLVMIRPrinter -lLLVMInterfaceStub -lLLVMFileCheck -lLLVMFuzzMutate -lLLVMScalarOpts -lLLVMInstCombine -lLLVMAggressiveInstCombine -lLLVMTransformUtils -lLLVMBitWriter -lLLVMAnalysis -lLLVMProfileData -lLLVMSymbolize -lLLVMDebugInfoBTF -lLLVMDebugInfoPDB -lLLVMDebugInfoMSF -lLLVMDebugInfoCodeView -lLLVMDebugInfoGSYM -lLLVMDebugInfoDWARF -lLLVMDebugInfoDWARFLowLevel -lLLVMObject -lLLVMTextAPI -lLLVMMCParser -lLLVMIRReader -lLLVMAsmParser -lLLVMMC -lLLVMBitReader -lLLVMFuzzerCLI -lLLVMCore -lLLVMRemarks -lLLVMBitstreamReader -lLLVMBinaryFormat -lLLVMTargetParser -lLLVMTableGen -lLLVMSupport -lLLVMDemangle -rdynamic -cargs:c++ -I/home/fernando/Build/gnat-llvm21/llvm/llvm-project-21.1.8.src/llvm/include -I/home/fernando/Build/gnat-llvm21/llvm/llvm-obj/include -std=c++17   -fno-exceptions -funwind-tables -fno-rtti -D_GNU_SOURCE -D_DEBUG -D_GLIBCXX_ASSERTIONS -DEXPERIMENTAL_KEY_INSTRUCTIONS -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS  -I/home/fernando/Build/gnat-llvm21/llvm-interface/../llvm/llvm-obj/tools/clang/include -I/home/fernando/Build/gnat-llvm21/llvm/llvm-project-21.1.8.src/clang/include -I.
Changing to object directory of "Gnat_LLVM": "/home/fernando/Build/gnat-llvm21/llvm-interface/obj/"
/home/fernando/bin/gnat-x86_64-linux-15.2.0-1/bin/g++ gnat1drv.o /tmp/GPR.41311/GNAT-TEMP-000003.TMP libgnat_llvm.a -static-libstdc++ -lclangBasic -L/home/fernando/Build/gnat-llvm21/llvm/llvm-obj/lib -lLLVMWindowsManifest -lLLVMXRay -lLLVMLibDriver -lLLVMDlltoolDriver -lLLVMTelemetry -lLLVMTextAPIBinaryReader -lLLVMCoverage -lLLVMLineEditor -lLLVMXCoreDisassembler -lLLVMXCoreCodeGen -lLLVMXCoreDesc -lLLVMXCoreInfo -lLLVMX86TargetMCA -lLLVMX86Disassembler -lLLVMX86AsmParser -lLLVMX86CodeGen -lLLVMX86Desc -lLLVMX86Info -lLLVMWebAssemblyDisassembler -lLLVMWebAssemblyAsmParser -lLLVMWebAssemblyCodeGen -lLLVMWebAssemblyUtils -lLLVMWebAssemblyDesc -lLLVMWebAssemblyInfo -lLLVMVEDisassembler -lLLVMVEAsmParser -lLLVMVECodeGen -lLLVMVEDesc -lLLVMVEInfo -lLLVMSystemZDisassembler -lLLVMSystemZAsmParser -lLLVMSystemZCodeGen -lLLVMSystemZDesc -lLLVMSystemZInfo -lLLVMSPIRVCodeGen -lLLVMSPIRVDesc -lLLVMSPIRVInfo -lLLVMSPIRVAnalysis -lLLVMSparcDisassembler -lLLVMSparcAsmParser -lLLVMSparcCodeGen -lLLVMSparcDesc -lLLVMSparcInfo -lLLVMRISCVTargetMCA -lLLVMRISCVDisassembler -lLLVMRISCVAsmParser -lLLVMRISCVCodeGen -lLLVMRISCVDesc -lLLVMRISCVInfo -lLLVMPowerPCDisassembler -lLLVMPowerPCAsmParser -lLLVMPowerPCCodeGen -lLLVMPowerPCDesc -lLLVMPowerPCInfo -lLLVMNVPTXCodeGen -lLLVMNVPTXDesc -lLLVMNVPTXInfo -lLLVMMSP430Disassembler -lLLVMMSP430AsmParser -lLLVMMSP430CodeGen -lLLVMMSP430Desc -lLLVMMSP430Info -lLLVMMipsDisassembler -lLLVMMipsAsmParser -lLLVMMipsCodeGen -lLLVMMipsDesc -lLLVMMipsInfo -lLLVMLoongArchDisassembler -lLLVMLoongArchAsmParser -lLLVMLoongArchCodeGen -lLLVMLoongArchDesc -lLLVMLoongArchInfo -lLLVMLanaiDisassembler -lLLVMLanaiCodeGen -lLLVMLanaiAsmParser -lLLVMLanaiDesc -lLLVMLanaiInfo -lLLVMHexagonDisassembler -lLLVMHexagonCodeGen -lLLVMHexagonAsmParser -lLLVMHexagonDesc -lLLVMHexagonInfo -lLLVMBPFDisassembler -lLLVMBPFAsmParser -lLLVMBPFCodeGen -lLLVMBPFDesc -lLLVMBPFInfo -lLLVMAVRDisassembler -lLLVMAVRAsmParser -lLLVMAVRCodeGen -lLLVMAVRDesc -lLLVMAVRInfo -lLLVMARMDisassembler -lLLVMARMAsmParser -lLLVMARMCodeGen -lLLVMARMDesc -lLLVMARMUtils -lLLVMARMInfo -lLLVMAMDGPUTargetMCA -lLLVMAMDGPUDisassembler -lLLVMAMDGPUAsmParser -lLLVMAMDGPUCodeGen -lLLVMAMDGPUDesc -lLLVMAMDGPUUtils -lLLVMAMDGPUInfo -lLLVMAArch64Disassembler -lLLVMAArch64AsmParser -lLLVMAArch64CodeGen -lLLVMAArch64Desc -lLLVMAArch64Utils -lLLVMAArch64Info -lLLVMOrcDebugging -lLLVMOrcJIT -lLLVMWindowsDriver -lLLVMMCJIT -lLLVMJITLink -lLLVMInterpreter -lLLVMExecutionEngine -lLLVMRuntimeDyld -lLLVMOrcTargetProcess -lLLVMOrcShared -lLLVMDWP -lLLVMDWARFCFIChecker -lLLVMDebugInfoLogicalView -lLLVMOption -lLLVMObjCopy -lLLVMMCA -lLLVMMCDisassembler -lLLVMLTO -lLLVMPasses -lLLVMHipStdPar -lLLVMCFGuard -lLLVMCoroutines -lLLVMipo -lLLVMVectorize -lLLVMSandboxIR -lLLVMLinker -lLLVMFrontendOpenMP -lLLVMFrontendOffloading -lLLVMObjectYAML -lLLVMFrontendOpenACC -lLLVMFrontendHLSL -lLLVMFrontendDriver -lLLVMInstrumentation -lLLVMFrontendDirective -lLLVMFrontendAtomic -lLLVMExtensions -lLLVMDWARFLinkerParallel -lLLVMDWARFLinkerClassic -lLLVMDWARFLinker -lLLVMGlobalISel -lLLVMMIRParser -lLLVMAsmPrinter -lLLVMSelectionDAG -lLLVMCodeGen -lLLVMTarget -lLLVMObjCARCOpts -lLLVMCodeGenTypes -lLLVMCGData -lLLVMIRPrinter -lLLVMInterfaceStub -lLLVMFileCheck -lLLVMFuzzMutate -lLLVMScalarOpts -lLLVMInstCombine -lLLVMAggressiveInstCombine -lLLVMTransformUtils -lLLVMBitWriter -lLLVMAnalysis -lLLVMProfileData -lLLVMSymbolize -lLLVMDebugInfoBTF -lLLVMDebugInfoPDB -lLLVMDebugInfoMSF -lLLVMDebugInfoCodeView -lLLVMDebugInfoGSYM -lLLVMDebugInfoDWARF -lLLVMDebugInfoDWARFLowLevel -lLLVMObject -lLLVMTextAPI -lLLVMMCParser -lLLVMIRReader -lLLVMAsmParser -lLLVMMC -lLLVMBitReader -lLLVMFuzzerCLI -lLLVMCore -lLLVMRemarks -lLLVMBitstreamReader -lLLVMBinaryFormat -lLLVMTargetParser -lLLVMTableGen -lLLVMSupport -lLLVMDemangle -rdynamic -L/home/fernando/Build/gnat-llvm21/llvm-interface/obj/ -L/home/fernando/Build/gnat-llvm21/llvm-interface/obj/ -L/home/fernando/bin/gnat-x86_64-linux-15.2.0-1/lib/gcc/x86_64-pc-linux-gnu/15.2.0/adalib/ /home/fernando/bin/gnat-x86_64-linux-15.2.0-1/lib/gcc/x86_64-pc-linux-gnu/15.2.0/adalib/libgnat.a -ldl -Wl,-rpath-link,/home/fernando/bin/gnat-x86_64-linux-15.2.0-1/lib/gcc/x86_64-pc-linux-gnu/15.2.0//adalib -static-libgcc -Wl,-z,origin,-rpath,$ORIGIN/../..//llvm/llvm-obj/lib:$ORIGIN/..//obj:$ORIGIN/../../../..//bin/gnat-x86_64-linux-15.2.0-1/lib/gcc/x86_64-pc-linux-gnu/15.2.0/adalib -o /home/fernando/Build/gnat-llvm21/llvm-interface/bin//llvm-gnat1
gprbuild: "llvm-gcc" up to date
/home/fernando/bin/gnat-x86_64-linux-15.2.0-1/bin/../lib/gcc/x86_64-pc-linux-gnu/15.2.0/../../../../x86_64-pc-linux-gnu/bin/ld: /home/fernando/Build/gnat-llvm21/llvm-interface/obj/osint-c.o: warning: relocation against `osint__B86s' in read-only section `.text'
/home/fernando/bin/gnat-x86_64-linux-15.2.0-1/bin/../lib/gcc/x86_64-pc-linux-gnu/15.2.0/../../../../x86_64-pc-linux-gnu/bin/ld: /home/fernando/Build/gnat-llvm21/llvm-interface/obj/osint-c.o: in function `osint__c__set_output_object_file_name':
/home/fernando/Build/gnat-llvm21/llvm-interface/gnat_src/osint-c.adb:474:(.text+0x29bc): undefined reference to `osint__B86s'
/home/fernando/bin/gnat-x86_64-linux-15.2.0-1/bin/../lib/gcc/x86_64-pc-linux-gnu/15.2.0/../../../../x86_64-pc-linux-gnu/bin/ld: warning: creating DT_TEXTREL in a PIE
collect2: error: ld returned 1 exit status
gprbuild: link of gnat1drv.adb failed
make[1]: *** [Makefile:93: build] Error 4
make[1]: Leaving directory '/home/fernando/Build/gnat-llvm21/llvm-interface'
make: *** [Makefile:2: all] Error 2

I am using the Alire provided compilers and GPRbuild. There seems to be an issue with PIE and osint which sound that either GCC/GNAT sources may have an issue or the bindings are not fully working...

I have no solution for this, so I am reporting the issue with hopes that it may help you, the developers, to maybe find something that is not working as intended.

Best regards,
Fer

Start with llvm/Makefile and the LLVM-21 build instructions, then reproduce the failure with the shown make command and inspect the final linker output. Done means the GNAT-LLVM build completes successfully against LLVM 21 with the configured targets.