simplify-rtl: Fix crash due to simplify_with_subreg_not [PR120059]

r16-286-gd84fbc516ea57d added a call to simplify_gen_subreg but didn't
check if the result of simplify_gen_subreg was non-null. simplify_gen_subreg
can return NULL if the subreg would be not valid. In the case below we had
a hard register for the SSE register xmm0 of mode SI and doing a subreg to
QI mode but QImode is not a valid mode for the SSE register so simplify_gen_subreg
would return NULL.

This adds the obvious check.

Pushed as obvious after bootstrap/test on x86_64-linux-gnu.

	PR rtl-optimization/120059

gcc/ChangeLog:

	* simplify-rtx.cc (simplify_with_subreg_not): Check the result
	of simplify_gen_subreg.

gcc/testsuite/ChangeLog:

	* gcc.dg/torture/pr120059-1.c: New test.

Signed-off-by: Andrew Pinski <quic_apinski@quicinc.com>

diff --git a/gcc/simplify-rtx.cc b/gcc/simplify-rtx.cc
index 7c4d8e6cfdbb20f6d706c766666ef2140a15be6f..7bcbe11370fa069e9008c9742e09b98b765b3eec 100644 (file)
--- a/gcc/simplify-rtx.cc
+++ b/gcc/simplify-rtx.cc
@@ -3063,6 +3063,10 @@ simplify_with_subreg_not (rtx_code binop, machine_mode mode, rtx op0, rtx op1)
                                        XEXP (SUBREG_REG (opn), 0),
                                        GET_MODE (SUBREG_REG (opn)),
                                        SUBREG_BYTE (opn));
+
+  if (!new_subreg)
+    return NULL_RTX;
+
   rtx new_not = simplify_gen_unary (NOT, mode, new_subreg, mode);
   if (opn == op0)
     return simplify_gen_binary (binop, mode, new_not, op1);

diff --git a/gcc/testsuite/gcc.dg/torture/pr120059-1.c b/gcc/testsuite/gcc.dg/torture/pr120059-1.c
new file mode 100644 (file)
index 0000000..36d0c5b
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr120059-1.c
@@ -0,0 +1,17 @@
+/* { dg-do compile } */
+/* { dg-options "-g" } */
+
+/* PR rtl-optimization/120059 */
+
+int a[4];
+int c, d;
+void f(void) {
+  for (int e = 0; e < 4; e++)
+    a[e] = e | c;
+  int b = 0;
+  if ((a[0] & 1) && (a[0] & 4))
+    b = 2;
+  if (a[0] & 16)
+    b |= 1;
+  d = ~b;
+}