Track LLVM 15 changes.

Per https://llvm.org/docs/OpaquePointers.html, support for non-opaque
pointers still exists and we can request that on our context.  We have
until LLVM 16 to move to opaque pointers, a much larger change.

Back-patch to 11, where LLVM support arrived.

Author: Thomas Munro <thomas.munro@gmail.com>
Author: Andres Freund <andres@anarazel.de>
Discussion: https://postgr.es/m/CAMHz58Sf_xncdyqsekoVsNeKcruKootLtVH6cYXVhhUR1oKPCg%40mail.gmail.com

configure

@@ -7481,6 +7481,95 @@ if test x"$pgac_cv_prog_CLANGXX_cxxflags__fexcess_precision_standard" = x"yes";
 fi
 
 
+  { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether ${CLANG} supports -Xclang -no-opaque-pointers, for BITCODE_CFLAGS" >&5
+$as_echo_n "checking whether ${CLANG} supports -Xclang -no-opaque-pointers, for BITCODE_CFLAGS... " >&6; }
+if ${pgac_cv_prog_CLANG_cflags__Xclang__no_opaque_pointers+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  pgac_save_CFLAGS=$CFLAGS
+pgac_save_CC=$CC
+CC=${CLANG}
+CFLAGS="${BITCODE_CFLAGS} -Xclang -no-opaque-pointers"
+ac_save_c_werror_flag=$ac_c_werror_flag
+ac_c_werror_flag=yes
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+int
+main ()
+{
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_compile "$LINENO"; then :
+  pgac_cv_prog_CLANG_cflags__Xclang__no_opaque_pointers=yes
+else
+  pgac_cv_prog_CLANG_cflags__Xclang__no_opaque_pointers=no
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+ac_c_werror_flag=$ac_save_c_werror_flag
+CFLAGS="$pgac_save_CFLAGS"
+CC="$pgac_save_CC"
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $pgac_cv_prog_CLANG_cflags__Xclang__no_opaque_pointers" >&5
+$as_echo "$pgac_cv_prog_CLANG_cflags__Xclang__no_opaque_pointers" >&6; }
+if test x"$pgac_cv_prog_CLANG_cflags__Xclang__no_opaque_pointers" = x"yes"; then
+  BITCODE_CFLAGS="${BITCODE_CFLAGS} -Xclang -no-opaque-pointers"
+fi
+
+  { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether ${CLANGXX} supports -Xclang -no-opaque-pointers, for BITCODE_CXXFLAGS" >&5
+$as_echo_n "checking whether ${CLANGXX} supports -Xclang -no-opaque-pointers, for BITCODE_CXXFLAGS... " >&6; }
+if ${pgac_cv_prog_CLANGXX_cxxflags__Xclang__no_opaque_pointers+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  pgac_save_CXXFLAGS=$CXXFLAGS
+pgac_save_CXX=$CXX
+CXX=${CLANGXX}
+CXXFLAGS="${BITCODE_CXXFLAGS} -Xclang -no-opaque-pointers"
+ac_save_cxx_werror_flag=$ac_cxx_werror_flag
+ac_cxx_werror_flag=yes
+ac_ext=cpp
+ac_cpp='$CXXCPP $CPPFLAGS'
+ac_compile='$CXX -c $CXXFLAGS $CPPFLAGS conftest.$ac_ext >&5'
+ac_link='$CXX -o conftest$ac_exeext $CXXFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ext $LIBS >&5'
+ac_compiler_gnu=$ac_cv_cxx_compiler_gnu
+
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+int
+main ()
+{
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_cxx_try_compile "$LINENO"; then :
+  pgac_cv_prog_CLANGXX_cxxflags__Xclang__no_opaque_pointers=yes
+else
+  pgac_cv_prog_CLANGXX_cxxflags__Xclang__no_opaque_pointers=no
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+ac_ext=c
+ac_cpp='$CPP $CPPFLAGS'
+ac_compile='$CC -c $CFLAGS $CPPFLAGS conftest.$ac_ext >&5'
+ac_link='$CC -o conftest$ac_exeext $CFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ext $LIBS >&5'
+ac_compiler_gnu=$ac_cv_c_compiler_gnu
+
+ac_cxx_werror_flag=$ac_save_cxx_werror_flag
+CXXFLAGS="$pgac_save_CXXFLAGS"
+CXX="$pgac_save_CXX"
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $pgac_cv_prog_CLANGXX_cxxflags__Xclang__no_opaque_pointers" >&5
+$as_echo "$pgac_cv_prog_CLANGXX_cxxflags__Xclang__no_opaque_pointers" >&6; }
+if test x"$pgac_cv_prog_CLANGXX_cxxflags__Xclang__no_opaque_pointers" = x"yes"; then
+  BITCODE_CXXFLAGS="${BITCODE_CXXFLAGS} -Xclang -no-opaque-pointers"
+fi
+
+
   NOT_THE_CFLAGS=""
   { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether ${CLANG} supports -Wunused-command-line-argument, for NOT_THE_CFLAGS" >&5
 $as_echo_n "checking whether ${CLANG} supports -Wunused-command-line-argument, for NOT_THE_CFLAGS... " >&6; }

configure.ac

@@ -627,6 +627,9 @@ if test "$with_llvm" = yes ; then
   PGAC_PROG_VARCC_VARFLAGS_OPT(CLANG, BITCODE_CFLAGS, [-fexcess-precision=standard])
   PGAC_PROG_VARCXX_VARFLAGS_OPT(CLANGXX, BITCODE_CXXFLAGS, [-fexcess-precision=standard])
 
+  PGAC_PROG_VARCC_VARFLAGS_OPT(CLANG, BITCODE_CFLAGS, [-Xclang -no-opaque-pointers])
+  PGAC_PROG_VARCXX_VARFLAGS_OPT(CLANGXX, BITCODE_CXXFLAGS, [-Xclang -no-opaque-pointers])
+
   NOT_THE_CFLAGS=""
   PGAC_PROG_VARCC_VARFLAGS_OPT(CLANG, NOT_THE_CFLAGS, [-Wunused-command-line-argument])
   if test -n "$NOT_THE_CFLAGS"; then

src/backend/jit/llvm/llvmjit.c

@@ -798,6 +798,16 @@ llvm_session_initialize(void)
 	LLVMInitializeNativeAsmPrinter();
 	LLVMInitializeNativeAsmParser();
 
+	/*
+	 * When targeting an LLVM version with opaque pointers enabled by
+	 * default, turn them off for the context we build our code in.  We don't
+	 * need to do so for other contexts (e.g. llvm_ts_context).  Once the IR is
+	 * generated, it carries the necessary information.
+	 */
+#if LLVM_VERSION_MAJOR > 14
+	LLVMContextSetOpaquePointers(LLVMGetGlobalContext(), false);
+#endif
+
 	/*
 	 * Synchronize types early, as that also includes inferring the target
 	 * triple.
@@ -1112,7 +1122,11 @@ llvm_resolve_symbols(LLVMOrcDefinitionGeneratorRef GeneratorObj, void *Ctx,
 					 LLVMOrcJITDylibRef JD, LLVMOrcJITDylibLookupFlags JDLookupFlags,
 					 LLVMOrcCLookupSet LookupSet, size_t LookupSetSize)
 {
+#if LLVM_VERSION_MAJOR > 14
+	LLVMOrcCSymbolMapPairs symbols = palloc0(sizeof(LLVMOrcCSymbolMapPair) * LookupSetSize);
+#else
 	LLVMOrcCSymbolMapPairs symbols = palloc0(sizeof(LLVMJITCSymbolMapPair) * LookupSetSize);
+#endif
 	LLVMErrorRef error;
 	LLVMOrcMaterializationUnitRef mu;
 
@@ -1230,7 +1244,11 @@ llvm_create_jit_instance(LLVMTargetMachineRef tm)
 	 * Symbol resolution support for "special" functions, e.g. a call into an
 	 * SQL callable function.
 	 */
+#if LLVM_VERSION_MAJOR > 14
+	ref_gen = LLVMOrcCreateCustomCAPIDefinitionGenerator(llvm_resolve_symbols, NULL, NULL);
+#else
 	ref_gen = LLVMOrcCreateCustomCAPIDefinitionGenerator(llvm_resolve_symbols, NULL);
+#endif
 	LLVMOrcJITDylibAddGenerator(LLVMOrcLLJITGetMainJITDylib(lljit), ref_gen);
 
 	return lljit;

src/backend/jit/llvm/meson.build

@@ -58,6 +58,9 @@ endif
 
 # XXX: Need to determine proper version of the function cflags for clang
 bitcode_cflags = ['-fno-strict-aliasing', '-fwrapv']
+if llvm.version().version_compare('>=15.0')
+  bitcode_cflags += ['-Xclang', '-no-opaque-pointers']
+endif
 bitcode_cflags += cppflags
 
 # XXX: Worth improving on the logic to find directories here