[gcc r11-5530] Fix print_multilib_info when default arguments appear in the option list with '!'

[Kito Cheng]

https://gcc.gnu.org/g:3a5d8ed231a0329822b7c032ba0834991732d2a0

commit r11-5530-g3a5d8ed231a0329822b7c032ba0834991732d2a0
Author: Kito Cheng <kito.cheng@sifive.com>
Date:   Wed Nov 25 17:04:33 2020 +0800

    Fix print_multilib_info when default arguments appear in the option list with '!'
    
    This issue is found when we try to always define MULTILIB_DEFAULTS for -march
    and -mabi for RISC-V back-end, however `-print-multi-lib` will skip
    multi-lib setting if match any one of flag in MULTILIB_DEFAULTS, even
    some options are specified in the option list with '!'.
    
    e.g.
    
    We have default march=rv32i and mabi=ilp32.
    
    And we have following multi-lib set:
    
    ". !march=rv32i !march=rv32im !march=rv32imafc !mabi=ilp32 !mabi=ilp32f;"
    "rv32i/ilp32 march=rv32i !march=rv32im !march=rv32imafc mabi=ilp32 !mabi=ilp32f;"
    "rv32im/ilp32 !march=rv32i march=rv32im !march=rv32imafc mabi=ilp32 !mabi=ilp32f;"
    "rv32imafc/ilp32f !march=rv32i !march=rv32ic !march=rv32im march=rv32imafc !mabi=ilp32 mabi=ilp32f;"
    
    `-print-multi-lib` willl show `.` and `rv32imafc/ilp32f` only, because
    the mabi=ilp32 is matched, however there is `!march=rv32i` in `rv32im/ilp32`, so
    `rv32im/ilp32` should keep, because it reject march=rv32i.
    
    Note: This can be reproduced via following configure options with patch [1]:
    gcc/configure --target=riscv64-elf --with-arch=rv32i --with-abi=ilp32 \
      --with-multilib-generator="rv32i-ilp32--;rv32im-ilp32--;rv32imafc-ilp32f--"
    
    [1] https://gcc.gnu.org/pipermail/gcc-patches/2020-November/559707.html
    
    gcc/ChangeLog:
    
            * gcc.c (print_multilib_info): Check default arguments not
            appeared in multi-lib option list with '!'

Diff:
---
 gcc/gcc.c | 23 +++++++++++++++++------
 1 file changed, 17 insertions(+), 6 deletions(-)

diff --git a/gcc/gcc.c b/gcc/gcc.c
index 16a6ee551de..bd4ad3b34ae 100644
--- a/gcc/gcc.c
+++ b/gcc/gcc.c
@@ -9775,6 +9775,7 @@ print_multilib_info (void)
   const char *p = multilib_select;
   const char *last_path = 0, *this_path;
   int skip;
+  int not_arg;
   unsigned int last_path_len = 0;
 
   while (*p != '\0')
@@ -9929,9 +9930,13 @@ print_multilib_info (void)
 		goto invalid_select;
 
 	      if (*q == '!')
-		arg = NULL;
+		{
+		  not_arg = 1;
+		  q++;
+		}
 	      else
-		arg = q;
+		not_arg = 0;
+	      arg = q;
 
 	      while (*q != ' ' && *q != ';')
 		{
@@ -9940,11 +9945,17 @@ print_multilib_info (void)
 		  ++q;
 		}
 
-	      if (arg != NULL
-		  && default_arg (arg, q - arg))
+	      if (default_arg (arg, q - arg))
 		{
-		  skip = 1;
-		  break;
+		  /* Stop checking if any default arguments appeared in not
+		     list.  */
+		  if (not_arg)
+		    {
+		      skip = 0;
+		      break;
+		    }
+		  else
+		    skip = 1;
 		}
 
 	      if (*q == ' ')