[PATCH] i386: Force inputs to a register to avoid lowpart_subreg failure [PR104458]

[Uros Bizjak via Gcc-patches]

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  <ubiz...@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.

Bootstrapped and regression tested on x86_64-linux-gnu {,-m32}.

Pushed to master.

Uros.

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;
+}