[gcc r12-7924] [PR105032] LRA: modify loop condition to find reload insns for hard reg splitting

[gcc r12-7924] [PR105032] LRA: modify loop condition to find reload insns for hard reg splitting

[Vladimir Makarov]

https://gcc.gnu.org/g:22b0476a814a4759bb68f38b9415624a0fe52a7d

commit r12-7924-g22b0476a814a4759bb68f38b9415624a0fe52a7d
Author: Vladimir N. Makarov <vmakarov@redhat.com>
Date:   Wed Mar 30 13:03:44 2022 -0400

    [PR105032] LRA: modify loop condition to find reload insns for hard reg splitting
    
    When trying to split hard reg live range to assign hard reg to a reload
    pseudo, LRA searches for reload insns of the reload pseudo
    assuming a specific order of the reload insns.  This order is violated if
    reload involved in inheritance transformation. In such case, the loop used
    for reload insn searching can become infinite.  The patch fixes this.
    
    gcc/ChangeLog:
    
            PR middle-end/105032
            * lra-assigns.cc (find_reload_regno_insns): Modify loop condition.
    
    gcc/testsuite/ChangeLog:
    
            PR middle-end/105032
            * gcc.target/i386/pr105032.c: New.

Diff:
---
 gcc/lra-assigns.cc                       |  3 ++-
 gcc/testsuite/gcc.target/i386/pr105032.c | 36 ++++++++++++++++++++++++++++++++
 2 files changed, 38 insertions(+), 1 deletion(-)

diff --git a/gcc/lra-assigns.cc b/gcc/lra-assigns.cc
index af30a673142..486e94f2006 100644
--- a/gcc/lra-assigns.cc
+++ b/gcc/lra-assigns.cc
@@ -1730,7 +1730,8 @@ find_reload_regno_insns (int regno, rtx_insn * &start, rtx_insn * &finish)
     {
       for (prev_insn = PREV_INSN (start_insn),
 	     next_insn = NEXT_INSN (start_insn);
-	   insns_num != 1 && (prev_insn != NULL || next_insn != NULL); )
+	   insns_num != 1 && (prev_insn != NULL
+			      || (next_insn != NULL && second_insn == NULL)); )
 	{
 	  if (prev_insn != NULL)
 	    {
diff --git a/gcc/testsuite/gcc.target/i386/pr105032.c b/gcc/testsuite/gcc.target/i386/pr105032.c
new file mode 100644
index 00000000000..57b21d3cd7a
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr105032.c
@@ -0,0 +1,36 @@
+/* { dg-do compile } */
+/* { dg-options "-w" } */
+/* { dg-additional-options "-m32" { target x86_64-*-* } } */
+
+typedef unsigned int size_t;	
+__extension__ typedef long int __off_t;
+typedef __off_t off_t;
+static void *__sys_mmap(void *addr, size_t length, int prot, int flags, int fd,
+			off_t offset)
+{
+  offset >>= 12;
+  return (void *)({ long _ret;
+      register long _num asm("eax") = (192);
+      register long _arg1 asm("ebx") = (long)(addr);
+      register long _arg2 asm("ecx") = (long)(length);
+      register long _arg3 asm("edx") = (long)(prot);
+      register long _arg4 asm("esi") = (long)(flags);
+      register long _arg5 asm("edi") = (long)(fd);
+      long _arg6 = (long)(offset);
+      asm volatile ("pushl	%[_arg6]\n\t"
+		    "pushl	%%ebp\n\t"
+		    "movl	4(%%esp), %%ebp\n\t"
+		    "int	$0x80\n\t"
+		    "popl	%%ebp\n\t"
+		    "addl	$4,%%esp\n\t"
+		    : "=a"(_ret)
+		    : "r"(_num), "r"(_arg1), "r"(_arg2), "r"(_arg3), "r"(_arg4),"r"(_arg5), [_arg6]"m"(_arg6)
+		    : "memory", "cc" );
+      _ret; });
+}
+
+int main(void)
+{
+  __sys_mmap(((void *)0), 0x1000, 0x1 | 0x2, 0x20 | 0x02, -1, 0);
+  return 0;
+}