[Bug rtl-optimization/66444] [5/6 Regression] Miscompilation of Xen since r211078

["vries at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66444

vries at gcc dot gnu.org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Assignee|unassigned at gcc dot gnu.org      |vries at gcc dot gnu.org

--- Comment #1 from vries at gcc dot gnu.org ---
Tentative patch:
...
diff --git a/gcc/postreload.c b/gcc/postreload.c
index 7ecca15..1cc7b14 100644
--- a/gcc/postreload.c
+++ b/gcc/postreload.c
@@ -1352,9 +1352,12 @@ reload_combine (void)
       if (CALL_P (insn))
        {
          rtx link;
+         HARD_REG_SET used_regs;
+
+         get_call_reg_set_usage (insn, &used_regs, call_used_reg_set);

          for (r = 0; r < FIRST_PSEUDO_REGISTER; r++)
-           if (call_used_regs[r])
+           if (TEST_HARD_REG_BIT (used_regs, r))
              {
                reg_state[r].use_index = RELOAD_COMBINE_MAX_USES;
                reg_state[r].store_ruid = reload_combine_ruid;
...

Output with patch:
...
        movabsq $962072674304, %r8
        salq    $5, %rax
        addq    %rax, %r8
        movq    %r8, %rdi
        call    fn1
        movq    %r8, %rdi
        call    fn2
...