Fix -freorder-blocks-and-partition glitch with Windows SEH (continued)

This fixes a thinko in the fix for the -freorder-blocks-and-partition
glitch with SEH on 64-bit Windows:
  https://gcc.gnu.org/pipermail/gcc-patches/2021-February/565208.html

Even if no exceptions are active, e.g. in C, we need to consider calls.

gcc/
	PR target/103274
	* config/i386/i386.c (ix86_output_call_insn): Beef up comment about
	nops emitted with SEH.
	* config/i386/winnt.c (i386_pe_seh_unwind_emit): When switching to
	the cold section, emit a nop before the directive if the previous
	active instruction is a call.

diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
index 2657e7817ae5a6c90ea578b8f2a11f2fcb408713..0e6bf3e0fefcdd79d78771c283e7e5e57a4aa40d 100644 (file)
--- a/gcc/config/i386/i386.c
+++ b/gcc/config/i386/i386.c
@@ -16438,8 +16438,10 @@ ix86_output_call_insn (rtx_insn *insn, rtx call_op)
            break;
 
          /* If we get to the epilogue note, prevent a catch region from
-            being adjacent to the standard epilogue sequence.  If non-
-            call-exceptions, we'll have done this during epilogue emission. */
+            being adjacent to the standard epilogue sequence.  Note that,
+            if non-call exceptions are enabled, we already did it during
+            epilogue expansion, or else, if the insn can throw internally,
+            we already did it during the reorg pass.  */
          if (NOTE_P (i) && NOTE_KIND (i) == NOTE_INSN_EPILOGUE_BEG
              && !flag_non_call_exceptions
              && !can_throw_internal (insn))

diff --git a/gcc/config/i386/winnt.c b/gcc/config/i386/winnt.c
index 7c0ea4f731cc195532a8e52b6ac9ecc232d9cb86..0aaf46f050a5734980003ac6197fff1e704e0d0a 100644 (file)
--- a/gcc/config/i386/winnt.c
+++ b/gcc/config/i386/winnt.c
@@ -1243,9 +1243,9 @@ i386_pe_seh_unwind_emit (FILE *out_file, rtx_insn *insn)
   seh = cfun->machine->seh;
   if (NOTE_P (insn) && NOTE_KIND (insn) == NOTE_INSN_SWITCH_TEXT_SECTIONS)
     {
-      /* See ix86_seh_fixup_eh_fallthru for the rationale.  */
+      /* See ix86_output_call_insn/seh_fixup_eh_fallthru for the rationale.  */
       rtx_insn *prev = prev_active_insn (insn);
-      if (prev && !insn_nothrow_p (prev))
+      if (prev && (CALL_P (prev) || !insn_nothrow_p (prev)))
        fputs ("\tnop\n", out_file);
       fputs ("\t.seh_endproc\n", out_file);
       seh->in_cold_section = true;