[gcc r16-1494] driver: Try to read spec from gcc_exec_prefix if possible

[Kito Cheng]

https://gcc.gnu.org/g:59fbc99f8ee35fc1a7bcae4bed3e7bfaec38b538

commit r16-1494-g59fbc99f8ee35fc1a7bcae4bed3e7bfaec38b538
Author: Kito Cheng <kito.cheng@sifive.com>
Date:   Tue Jun 10 11:17:45 2025 +0800

    driver: Try to read spec from gcc_exec_prefix if possible
    
    GCC will try to read the spec file from the directory where it is
    installed, but it should try to read from gcc_exec_prefix rather than
    standard_exec_prefix, because the latter is not the right one if
    compiler has been relocated into other places other than the path
    specfied at configuration time.
    
    gcc/ChangeLog:
    
            * gcc.cc (driver::set_up_specs): Use gcc_exec_prefix to
            read the spec file rather than standard_exec_prefix.

Diff:
---
 gcc/gcc.cc | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/gcc/gcc.cc b/gcc/gcc.cc
index 4e61de2a47c3..235fe8019880 100644
--- a/gcc/gcc.cc
+++ b/gcc/gcc.cc
@@ -8506,11 +8506,13 @@ driver::set_up_specs () const
   spec_machine_suffix = just_machine_suffix;
 #endif
 
+  const char *exec_prefix
+    = gcc_exec_prefix ? gcc_exec_prefix : standard_exec_prefix;
   /* We need to check standard_exec_prefix/spec_machine_suffix/specs
      for any override of as, ld and libraries.  */
-  specs_file = (char *) alloca (strlen (standard_exec_prefix)
-		       + strlen (spec_machine_suffix) + sizeof ("specs"));
-  strcpy (specs_file, standard_exec_prefix);
+  specs_file = (char *) alloca (
+    strlen (exec_prefix) + strlen (spec_machine_suffix) + sizeof ("specs"));
+  strcpy (specs_file, exec_prefix);
   strcat (specs_file, spec_machine_suffix);
   strcat (specs_file, "specs");
   if (access (specs_file, R_OK) == 0)