[gcc(refs/vendors/ARM/heads/morello)] Remove LSB when finding landing pad correlating to a PC

[gcc(refs/vendors/ARM/heads/morello)] Remove LSB when finding landing pad correlating to a PC

[Matthew Malcomson]

https://gcc.gnu.org/g:567c00d744255b38c1ae988922c279948b409d3d

commit 567c00d744255b38c1ae988922c279948b409d3d
Author: Matthew Malcomson <matthew.malcomson@arm.com>
Date:   Fri Dec 10 16:31:28 2021 +0000

    Remove LSB when finding landing pad correlating to a PC
    
    Remove LSB when finding landing pad correlating to a PC
    
    In the C personality function we need to find the landing pad associated
    with a given PC.  To find the relevant landing pad we need to look for
    the relevant PC location.   Since the PC we get from _Unwind_GetIP is a
    valid sealed capability and removing that LSB loses the capability
    validity we add code to maintain the clear difference between the IP
    pointer and the IP as an address in the C personality function.
    
    N.b. the implementation design of maintaining two variables is not
    really necessary, we have no reason to need the IP from before.  However
    it's still nice to maintain a clear distinction between the two ways
    of representing IP.
    
    N.b. this changes the cleanup-5.c test from FAIL to PASS because we now
    correctly identify the LSDA for the instruction that we are in (rather
    than the instruction that would come after the current branch).

Diff:
---
 libgcc/unwind-c.c | 18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/libgcc/unwind-c.c b/libgcc/unwind-c.c
index af8e390bdbd..d1831bed92c 100644
--- a/libgcc/unwind-c.c
+++ b/libgcc/unwind-c.c
@@ -128,7 +128,8 @@ PERSONALITY_FUNCTION (int version,
 {
   lsda_header_info info;
   const unsigned char *language_specific_data, *p;
-  _Unwind_Ptr landing_pad, ip;
+  _Unwind_Ptr landing_pad, ip_ptr;
+  _Unwind_Address ip;
   int ip_before_insn = 0;
 
 #ifdef __ARM_EABI_UNWINDER__
@@ -139,8 +140,8 @@ PERSONALITY_FUNCTION (int version,
      function and LSDA pointers.  The ARM implementation caches these in
      the exception header (UCB).  To avoid rewriting everything we make a
      virtual scratch register point at the UCB.  */
-  ip = (_Unwind_Ptr) ue_header;
-  _Unwind_SetGR (context, UNWIND_POINTER_REG, ip);
+  ip_ptr = (_Unwind_Ptr) ue_header;
+  _Unwind_SetGR (context, UNWIND_POINTER_REG, ip_ptr);
 #else
   if (version != 1)
     return _URC_FATAL_PHASE1_ERROR;
@@ -160,10 +161,17 @@ PERSONALITY_FUNCTION (int version,
   /* Parse the LSDA header.  */
   p = parse_lsda_header (context, language_specific_data, &info);
 #ifdef HAVE_GETIPINFO
-  ip = _Unwind_GetIPInfo (context, &ip_before_insn);
+  ip_ptr = _Unwind_GetIPInfo (context, &ip_before_insn);
 #else
-  ip = _Unwind_GetIP (context);
+  ip_ptr = _Unwind_GetIP (context);
 #endif
+
+#ifdef __USING_SJLJ_EXCEPTIONS__
+  ip = (_Unwind_Address) ip_ptr;
+#else
+  ip = __builtin_code_address_from_pointer (ip_ptr);
+#endif
+
   if (! ip_before_insn)
     --ip;
   landing_pad = 0;