5 files changed, 102 insertions, 10 deletions
diff --git a/libgcc/ChangeLog b/libgcc/ChangeLog
index a9f4a1f..75ba93e 100644
--- a/libgcc/ChangeLog
+++ b/libgcc/ChangeLog
@@ -1,3 +1,22 @@
+2025-12-09  John Ericson  <git@JohnEricson.me>
+
+	* config/rs6000/t-slibgcc-aix: Instead of using a
+	TARGET_SYSTEM_ROOT make variable, just define a shell variable
+	as part of the rule and use that.
+
+2025-12-09  John Ericson  <git@JohnEricson.me>
+
+	* Makefile.in: Define NO_PIE_CFLAGS make variable via autoconf
+	substitution.
+	* configure: Regenerate.
+	* configure.ac: New configure check to define NO_PIE_CFLAGS
+	using the algorithm Andrew asked for in the linked mail.
+
+2025-12-09  John Ericson  <git@johnericson.me>
+
+	* configure: Regenerate.
+	* configure.ac: Use GCC_AC_THREAD_MODEL instead of hand-rolled
+
 2025-11-27  Lulu Cheng  <chenglulu@loongson.cn>
 
 	* config/loongarch/cpuinfo.c (HWCAP_LOONGARCH_LSX): Define
diff --git a/libgcc/Makefile.in b/libgcc/Makefile.in
index 32a5a15..f0cbcb8 100644
--- a/libgcc/Makefile.in
+++ b/libgcc/Makefile.in
@@ -298,6 +298,8 @@ override CFLAGS := $(filter-out -fprofile-generate -fprofile-use,$(CFLAGS))
 INTERNAL_CFLAGS = $(CFLAGS) $(LIBGCC2_CFLAGS) $(HOST_LIBGCC2_CFLAGS) \
 		  $(INCLUDES) @set_have_cc_tls@ @set_use_emutls@
 
+NO_PIE_CFLAGS = @NO_PIE_CFLAGS@
+
 # Options to use when compiling crtbegin/end.
 CRTSTUFF_CFLAGS = -O2 $(GCC_CFLAGS) $(INCLUDES) $(MULTILIB_CFLAGS) -g0 \
   $(NO_PIE_CFLAGS) -finhibit-size-directive -fno-inline -fno-exceptions \
diff --git a/libgcc/config/rs6000/t-slibgcc-aix b/libgcc/config/rs6000/t-slibgcc-aix
index 6333687..4a3d624 100644
--- a/libgcc/config/rs6000/t-slibgcc-aix
+++ b/libgcc/config/rs6000/t-slibgcc-aix
@@ -40,7 +40,9 @@ SHLIB_LINK = \
 	  -Wl,-bE:@shlib_map_file@ -o shr.o \
 	  @multilib_flags@ @shlib_objs@ -lc \
 	  `case @multilib_dir@ in \
-	  *pthread*) echo -L$(TARGET_SYSTEM_ROOT)/usr/lib/threads -lpthreads -lc_r $(TARGET_SYSTEM_ROOT)/usr/lib/libc.a ;; \
+	  *pthread*) \
+	    TARGET_SYSTEM_ROOT=\`$(CC) -print-sysroot\`; \
+	    echo -L$$TARGET_SYSTEM_ROOT/usr/lib/threads -lpthreads -lc_r $$TARGET_SYSTEM_ROOT/usr/lib/libc.a ;; \
 	  *) echo -lc ;; esac` ; \
 	  rm -f tmp-@shlib_base_name@.a ; \
 	  $(AR_CREATE_FOR_TARGET) tmp-@shlib_base_name@.a shr.o ; \
@@ -53,7 +55,9 @@ SHLIB_LINK = \
 	  -Wl,-bE:@shlib_map_file@ -o $$shr.o \
 	  @multilib_flags@ @shlib_objs@ -lc \
 	  `case @multilib_dir@ in \
-	  *pthread*) echo -L$(TARGET_SYSTEM_ROOT)/usr/lib/threads -lpthreads -lc_r $(TARGET_SYSTEM_ROOT)/usr/lib/libc.a ;; \
+	  *pthread*) \
+	    TARGET_SYSTEM_ROOT=\`$(CC) -print-sysroot\`; \
+	    echo -L$$TARGET_SYSTEM_ROOT/usr/lib/threads -lpthreads -lc_r $$TARGET_SYSTEM_ROOT/usr/lib/libc.a ;; \
 	  *) echo -lc ;; esac` ; \
 	  $(STRIP_FOR_TARGET) -X32_64 -e $$shr.o ; \
 	  { echo "\#! $(SHLIB_SONAME)($$shr.o)" ; \
diff --git a/libgcc/configure b/libgcc/configure
index d5e80d2..fe7a21c2 100755
--- a/libgcc/configure
+++ b/libgcc/configure
@@ -610,6 +610,7 @@ accel_dir_suffix
 use_tm_clone_registry
 force_explicit_eh_registry
 CET_FLAGS
+NO_PIE_CFLAGS
 fixed_point
 enable_decimal_float
 decimal_float
@@ -4836,6 +4837,40 @@ $as_echo "$libgcc_cv_fixed_point" >&6; }
 fixed_point=$libgcc_cv_fixed_point
 
 
+# Check whether the compiler defines __PIE__ by default, so -fno-PIE is needed.
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether the compiler defines __PIE__" >&5
+$as_echo_n "checking whether the compiler defines __PIE__... " >&6; }
+if ${libgcc_cv_no_pie_cflags+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+#ifdef __PIE__
+#error __PIE__ defined
+#endif
+
+int
+main ()
+{
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_compile "$LINENO"; then :
+  libgcc_cv_no_pie_cflags=''
+else
+  libgcc_cv_no_pie_cflags='-fno-PIE'
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libgcc_cv_no_pie_cflags" >&5
+$as_echo "$libgcc_cv_no_pie_cflags" >&6; }
+
+NO_PIE_CFLAGS=$libgcc_cv_no_pie_cflags
+
+
 # For platforms with the unwind ABI which includes an unwind library,
 # libunwind, we can choose to use the system libunwind.
 # config.gcc also contains tests of with_system_libunwind.
@@ -5046,11 +5081,28 @@ $as_echo "$acl_cv_prog_gnu_ld" >&6; }
 with_gnu_ld=$acl_cv_prog_gnu_ld
 
 
-{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for thread model used by GCC" >&5
-$as_echo_n "checking for thread model used by GCC... " >&6; }
-target_thread_file=`$CC -v 2>&1 | sed -n 's/^Thread model: //p'`
-{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $target_thread_file" >&5
-$as_echo "$target_thread_file" >&6; }
+
+# Specify the threading model for this GCC runtime library
+# Pass with no value to take from compiler's metadata
+# Pass with a value to specify a thread package
+# 'single' means single threaded -- without threads.
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for the threading model used by GCC" >&5
+$as_echo_n "checking for the threading model used by GCC... " >&6; }
+if ${gcc_cv_target_thread_file+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+
+  # Set new cache variable
+  gcc_cv_target_thread_file=`$CC -v 2>&1 | sed -n 's/^Thread model: //p'`
+
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $gcc_cv_target_thread_file" >&5
+$as_echo "$gcc_cv_target_thread_file" >&6; }
+# Set variable name (not prefixed enough to be a good cache variable
+# name) traditionally used for this purpose, to avoid having to change
+# a bunch of configure scripts.
+target_thread_file="$gcc_cv_target_thread_file"
+
 
 # Check for assembler CFI support.
 { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether assembler supports CFI directives" >&5
@@ -5737,6 +5789,9 @@ case $target_thread_file in
     vxworks)	thread_header=config/gthr-vxworks.h ;;
     win32)	thread_header=config/i386/gthr-win32.h ;;
     mcf)	thread_header=config/i386/gthr-mcf.h ;;
+    *)
+        as_fn_error $? "No known header for threading model '$target_thread_file'." "$LINENO" 5
+        ;;
 esac
 
 
diff --git a/libgcc/configure.ac b/libgcc/configure.ac
index 65cd3c6..5945243 100644
--- a/libgcc/configure.ac
+++ b/libgcc/configure.ac
@@ -258,6 +258,20 @@ AC_CACHE_CHECK([whether fixed-point is supported], [libgcc_cv_fixed_point],
 fixed_point=$libgcc_cv_fixed_point
 AC_SUBST(fixed_point)
 
+# Check whether the compiler defines __PIE__ by default, so -fno-PIE is needed.
+AC_CACHE_CHECK([whether the compiler defines __PIE__], [libgcc_cv_no_pie_cflags],
+  [AC_COMPILE_IFELSE(
+     [AC_LANG_PROGRAM([[
+#ifdef __PIE__
+#error __PIE__ defined
+#endif
+     ]], [[]])],
+     [libgcc_cv_no_pie_cflags=''],
+     [libgcc_cv_no_pie_cflags='-fno-PIE'])])
+
+NO_PIE_CFLAGS=$libgcc_cv_no_pie_cflags
+AC_SUBST([NO_PIE_CFLAGS])
+
 # For platforms with the unwind ABI which includes an unwind library,
 # libunwind, we can choose to use the system libunwind.
 # config.gcc also contains tests of with_system_libunwind.
@@ -305,9 +319,7 @@ AC_SUBST([use_tm_clone_registry])
 
 AC_LIB_PROG_LD_GNU
 
-AC_MSG_CHECKING([for thread model used by GCC])
-target_thread_file=`$CC -v 2>&1 | sed -n 's/^Thread model: //p'`
-AC_MSG_RESULT([$target_thread_file]) 
+GCC_AC_THREAD_MODEL
 
 # Check for assembler CFI support.
 AC_CACHE_CHECK([whether assembler supports CFI directives], [libgcc_cv_cfi],