diff mbox series

[committed,PR103074] LRA: Check new conflicts when splitting hard reg live range

Message ID d27881fe-104e-68da-f5bf-7b095f3f2c6e@redhat.com
State New
Headers show
Series [committed,PR103074] LRA: Check new conflicts when splitting hard reg live range | expand

Commit Message

Vladimir Makarov March 10, 2022, 9:21 p.m. UTC 
The following patch solves

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103074

The patch was successfully bootstrapped and tested on x86-64 and aarch64.
diff mbox series

Patch

commit d8e5fff6b74b82c2ac3254be9a1f0fb6b30dbdbf
Author: Vladimir N. Makarov <vmakarov@redhat.com>
Date:   Thu Mar 10 16:16:00 2022 -0500

    [PR103074] LRA: Check new conflicts when splitting hard reg live range.
    
    Splitting hard register live range can create (artificial)
    conflict of the hard register with another pseudo because of simplified
    conflict calculation in LRA.  We should check such conflict on the next
    assignment sub-pass and spill and reassign the pseudo if necessary.
    The patch implements this.
    
    gcc/ChangeLog:
    
            PR target/103074
            * lra-constraints.cc (split_reg): Set up
            check_and_force_assignment_correctness_p when splitting hard
            register live range.
    
    gcc/testsuite/ChangeLog:
    
            PR target/103074
            * gcc.target/i386/pr103074.c: New.

diff --git a/gcc/lra-constraints.cc b/gcc/lra-constraints.cc
index 080b44ad87a..d92ab76908c 100644
--- a/gcc/lra-constraints.cc
+++ b/gcc/lra-constraints.cc
@@ -5994,12 +5994,17 @@  split_reg (bool before_p, int original_regno, rtx_insn *insn,
 			 before_p ? NULL : save,
 			 call_save_p
 			 ?  "Add save<-reg" : "Add split<-reg");
-  if (nregs > 1)
+  if (nregs > 1 || original_regno < FIRST_PSEUDO_REGISTER)
     /* If we are trying to split multi-register.  We should check
        conflicts on the next assignment sub-pass.  IRA can allocate on
        sub-register levels, LRA do this on pseudos level right now and
        this discrepancy may create allocation conflicts after
-       splitting.  */
+       splitting.
+
+       If we are trying to split hard register we should also check conflicts
+       as such splitting can create artificial conflict of the hard register
+       with another pseudo because of simplified conflict calculation in
+       LRA.  */
     check_and_force_assignment_correctness_p = true;
   if (lra_dump_file != NULL)
     fprintf (lra_dump_file,
diff --git a/gcc/testsuite/gcc.target/i386/pr103074.c b/gcc/testsuite/gcc.target/i386/pr103074.c
new file mode 100644
index 00000000000..276ad82a1de
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr103074.c
@@ -0,0 +1,16 @@ 
+/* { dg-do compile } */
+/* { dg-options "-march=bonnell -Os -fPIC -fschedule-insns -w" } */
+
+void
+serialize_collection (char *ptr, int a, int need_owner)
+{
+  if (need_owner)
+    __builtin_sprintf(ptr, "%d:%d", 0, a);
+  else
+    {
+      static char buff[32];
+
+      __builtin_sprintf(buff, "%d:%d", a >> 32, a);
+      __builtin_sprintf(ptr, "%d:%d:\"%s\"", 0, 0, buff);
+    }
+}