[gcc r11-9786] Fix target/100106 ICE in gen_movdi

[Richard Biener]

https://gcc.gnu.org/g:5155015ce57dc133e006f87fdf0237a5f259bebd

commit r11-9786-g5155015ce57dc133e006f87fdf0237a5f259bebd
Author: Bernd Edlinger <bernd.edlinger@hotmail.de>
Date:   Wed Apr 21 14:13:04 2021 +0200

    Fix target/100106 ICE in gen_movdi
    
    As the test case shows, the outer mode may have a higher alignment
    requirement than the inner mode here.
    
    2021-04-27  Bernd Edlinger  <bernd.edlinger@hotmail.de>
    
            PR target/100106
            * simplify-rtx.c (simplify_context::simplify_subreg): Check the
            memory alignment for the outer mode.
    
            * gcc.c-torture/compile/pr100106.c: New testcase.
    
    (cherry picked from commit c33db31d9ad96f6414460315c12b4b505fad5dd7)

Diff:
---
 gcc/simplify-rtx.c                             |  1 +
 gcc/testsuite/gcc.c-torture/compile/pr100106.c | 11 +++++++++++
 2 files changed, 12 insertions(+)

diff --git a/gcc/simplify-rtx.c b/gcc/simplify-rtx.c
index b58ab5e51c7..b9f4f7928d2 100644
--- a/gcc/simplify-rtx.c
+++ b/gcc/simplify-rtx.c
@@ -7230,6 +7230,7 @@ simplify_context::simplify_subreg (machine_mode outermode, rtx op,
          have instruction to move the whole thing.  */
       && (! MEM_VOLATILE_P (op)
 	  || ! have_insn_for (SET, innermode))
+      && !(STRICT_ALIGNMENT && MEM_ALIGN (op) < GET_MODE_ALIGNMENT (outermode))
       && known_le (outersize, innersize))
     return adjust_address_nv (op, outermode, byte);
 
diff --git a/gcc/testsuite/gcc.c-torture/compile/pr100106.c b/gcc/testsuite/gcc.c-torture/compile/pr100106.c
new file mode 100644
index 00000000000..7f98b4f992e
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/compile/pr100106.c
@@ -0,0 +1,11 @@
+union a {
+  float _Complex b;
+  long long c;
+};
+
+void g(union a);
+
+void e() {
+  union a f = {1.0f};
+  g(f);
+}