The following patch fixes
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102627
The patch was successfully bootstrapped and tested on x86-64.
commit fab2d977e69539aad9bef81caff17de48e53aedf (HEAD -> master)
Author: Vladimir N. Makarov <vmaka...@redhat.com>
Date: Fri Oct 8 10:16:09 2021 -0400
[PR102627] Use at least natural mode during splitting hard reg live range
In the PR test case SImode was used to split live range of cx on x86-64
because it was the biggest mode for this hard reg in the function. But
all 64-bits of cx contain structure members. We need always to use at least
natural mode of hard reg in splitting to fix this problem.
gcc/ChangeLog:
PR rtl-optimization/102627
* lra-constraints.c (split_reg): Use at least natural mode of hard reg.
gcc/testsuite/ChangeLog:
PR rtl-optimization/102627
* gcc.target/i386/pr102627.c: New test.
diff --git a/gcc/lra-constraints.c b/gcc/lra-constraints.c
index 4d734548c38..8f75125fc2e 100644
--- a/gcc/lra-constraints.c
+++ b/gcc/lra-constraints.c
@@ -5799,11 +5799,12 @@ split_reg (bool before_p, int original_regno, rtx_insn *insn,
part of a multi-word register. In that case, just use the reg_rtx
mode. Do the same also if the biggest mode was larger than a register
or we can not compare the modes. Otherwise, limit the size to that of
- the biggest access in the function. */
+ the biggest access in the function or to the natural mode at least. */
if (mode == VOIDmode
|| !ordered_p (GET_MODE_PRECISION (mode),
GET_MODE_PRECISION (reg_rtx_mode))
- || paradoxical_subreg_p (mode, reg_rtx_mode))
+ || paradoxical_subreg_p (mode, reg_rtx_mode)
+ || maybe_gt (GET_MODE_PRECISION (reg_rtx_mode), GET_MODE_PRECISION (mode)))
{
original_reg = regno_reg_rtx[hard_regno];
mode = reg_rtx_mode;
diff --git a/gcc/testsuite/gcc.target/i386/pr102627.c b/gcc/testsuite/gcc.target/i386/pr102627.c
new file mode 100644
index 00000000000..8ab9acaf002
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr102627.c
@@ -0,0 +1,41 @@
+/* PR rtl-optimization/102627 */
+/* { dg-do run } */
+/* { dg-options "-O1" } */
+
+int a, f, l, m, q, c, d, g;
+long b, e;
+struct g {
+ signed h;
+ signed i;
+ unsigned j;
+ unsigned k;
+};
+unsigned n;
+char o;
+int *p = &m;
+long r(int s) { return s && b ?: b; }
+long __attribute__((noipa)) v() {
+ l = 0 || r(n & o);
+ return q;
+}
+void w(int, unsigned, struct g x) {
+ c ?: a;
+ for (; d < 2; d++)
+ *p = x.k;
+}
+struct g __attribute__((noipa)) y() {
+ struct g h = {3, 908, 1, 20};
+ for (; g; g++)
+ ;
+ return h;
+}
+int main() {
+ long t;
+ struct g u = y();
+ t = e << f;
+ w(0, t, u);
+ v(0, 4, 4, 4);
+ if (m != 20)
+ __builtin_abort ();
+ return 0;
+}
