[gcc r12-7146] i386: Force inputs to a register to avoid lowpart_subreg failure [PR104458]

[Uros Bizjak <uros@gcc.gnu.org>]

https://gcc.gnu.org/g:2b399dbabd48639ab4daac462c9d82c6cf3f99cc

commit r12-7146-g2b399dbabd48639ab4daac462c9d82c6cf3f99cc
Author: Uros Bizjak <ubizjak@gmail.com>
Date:   Wed Feb 9 20:18:10 2022 +0100

    i386: Force inputs to a register to avoid lowpart_subreg failure [PR104458]
    
    Input operands can be in the form of:
    
            (subreg:DI (reg:V2SF 96) 0)
    
    which chokes lowpart_subreg. Force inputs to a register, which is
    preferable even when the input operand is from memory.
    
    2022-02-09  Uroš Bizjak  <ubizjak@gmail.com>
    
    gcc/ChangeLog:
    
            PR target/104458
            * config/i386/i386-expand.cc (ix86_split_idivmod):
            Force operands[2] and operands[3] into a register..
    
    gcc/testsuite/ChangeLog:
    
            PR target/104458
            * gcc.target/i386/pr104458.c: New test.

Diff:
---
 gcc/config/i386/i386-expand.cc           |  3 +++
 gcc/testsuite/gcc.target/i386/pr104458.c | 13 +++++++++++++
 2 files changed, 16 insertions(+)

diff --git a/gcc/config/i386/i386-expand.cc b/gcc/config/i386/i386-expand.cc
index eb1930ba375..ce9607e36de 100644
--- a/gcc/config/i386/i386-expand.cc
+++ b/gcc/config/i386/i386-expand.cc
@@ -1407,6 +1407,9 @@ ix86_split_idivmod (machine_mode mode, rtx operands[],
   rtx scratch, tmp0, tmp1, tmp2;
   rtx (*gen_divmod4_1) (rtx, rtx, rtx, rtx);
 
+  operands[2] = force_reg (mode, operands[2]);
+  operands[3] = force_reg (mode, operands[3]);
+
   switch (mode)
     {
     case E_SImode:
diff --git a/gcc/testsuite/gcc.target/i386/pr104458.c b/gcc/testsuite/gcc.target/i386/pr104458.c
new file mode 100644
index 00000000000..d1d28c13118
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr104458.c
@@ -0,0 +1,13 @@
+/* PR target/104458 */
+/* { dg-do compile { target { ! ia32 } } } */
+/* { dg-options "-O1 -m8bit-idiv" } */
+
+typedef float __attribute__((__vector_size__ (8))) F;
+
+int i;
+
+void
+foo (F f)
+{
+  i += i % (long) f;
+}