[PATCH 18/19][GCC-8] aarch64: Fix ICE due to aarch64_gen_compare_reg_maybe_ze [PR94435]

[Andre Vieira (lists)]

The following testcase ICEs, because aarch64_gen_compare_reg_maybe_ze emits
invalid RTL.
For y_mode [QH]Imode it expects y to be of that mode (or CONST_INT that fits
into that mode) and x being SImode; for non-CONST_INT y it zero extends y
into SImode and compares that against x, for CONST_INT y it zero extends y
into SImode.  The problem is that when the zero extended constant isn't
usable directly, it forces it into a REG, but with y_mode mode, and then
compares against y.  That is wrong, because it should force it into a SImode
REG and compare that way.

2020-04-16  Andre Vieira <andre.simoesdiasvie...@arm.com>

    Backport from mainline
    2020-04-02  Jakub Jelinek <ja...@redhat.com>

    PR target/94435
    * config/aarch64/aarch64.c (aarch64_gen_compare_reg_maybe_ze): For
    y_mode E_[QH]Imode and y being a CONST_INT, change y_mode to SImode.

    * gcc.target/aarch64/pr94435.c: New test.


diff --git a/gcc/config/aarch64/aarch64.c b/gcc/config/aarch64/aarch64.c
index 
21124b5a3479dd388eb767402e080e2181153467..6bac63402e508027e77a9f4557cb10c578ea7c2c
 100644
--- a/gcc/config/aarch64/aarch64.c
+++ b/gcc/config/aarch64/aarch64.c
@@ -1556,7 +1556,10 @@ aarch64_gen_compare_reg_maybe_ze (RTX_CODE code, rtx x, 
rtx y,
   if (y_mode == E_QImode || y_mode == E_HImode)
     {
       if (CONST_INT_P (y))
-       y = GEN_INT (INTVAL (y) & GET_MODE_MASK (y_mode));
+       {
+         y = GEN_INT (INTVAL (y) & GET_MODE_MASK (y_mode));
+         y_mode = SImode;
+       }
       else
        {
          rtx t, cc_reg;
diff --git a/gcc/testsuite/gcc.target/aarch64/pr94435.c 
b/gcc/testsuite/gcc.target/aarch64/pr94435.c
new file mode 100644
index 
0000000000000000000000000000000000000000..5713c14d5f90b1d42f92d040e9030ecc03c97d51
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/pr94435.c
@@ -0,0 +1,25 @@
+/* PR target/94435 */
+/* { dg-do compile } */
+/* { dg-options "-march=armv8-a+nolse -moutline-atomics" } */
+
+int b, c, d, e, f, h;
+short g;
+int foo (int) __attribute__ ((__const__));
+
+void
+bar (void)
+{
+  while (1)
+    {
+      while (1)
+       {
+         __atomic_load_n (&e, 0);
+         if (foo (2))
+           __sync_val_compare_and_swap (&c, 0, f);
+         b = 1;
+         if (h == e)
+           break;
+       }
+      __sync_val_compare_and_swap (&g, -1, f);
+    }
+}