expr: Fix ICE on BFmode -> SFmode conversion of constant [PR107262]

I forgot to handle the case where lowpart_subreg returns a VOIDmode
CONST_INT, in that case convert_mode_scalar obviously doesn't work.

The following patch fixes that.

2022-10-19  Jakub Jelinek  <jakub@redhat.com>

	PR middle-end/107262
	* expr.cc (convert_mode_scalar): For BFmode -> SFmode conversions
	of constants, use simplify_unary_operation if fromi has VOIDmode
	instead of recursive convert_mode_scalar.

	* gcc.dg/pr107262.c: New test.

diff --git a/gcc/expr.cc b/gcc/expr.cc
index 4c892d6..efe387e 100644 (file)
--- a/gcc/expr.cc
+++ b/gcc/expr.cc
@@ -416,8 +416,15 @@ convert_mode_scalar (rtx to, rtx from, int unsignedp)
                  rtx tof = NULL_RTX;
                  if (fromi)
                    {
-                     rtx toi = gen_reg_rtx (toi_mode);
-                     convert_mode_scalar (toi, fromi, 1);
+                     rtx toi;
+                     if (GET_MODE (fromi) == VOIDmode)
+                       toi = simplify_unary_operation (ZERO_EXTEND, toi_mode,
+                                                       fromi, fromi_mode);
+                     else
+                       {
+                         toi = gen_reg_rtx (toi_mode);
+                         convert_mode_scalar (toi, fromi, 1);
+                       }
                      toi
                        = maybe_expand_shift (LSHIFT_EXPR, toi_mode, toi,
                                              GET_MODE_PRECISION (to_mode)

diff --git a/gcc/testsuite/gcc.dg/pr107262.c b/gcc/testsuite/gcc.dg/pr107262.c
new file mode 100644 (file)
index 0000000..2ced047
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr107262.c
@@ -0,0 +1,13 @@
+/* PR middle-end/107262 */
+/* { dg-do compile } */
+/* { dg-options "-O2 -ffast-math" } */
+/* { dg-add-options bfloat16 } */
+/* { dg-require-effective-target bfloat16_runtime } */
+
+__bf16
+foo (__bf16 a)
+{
+  __bf16 b = 0;
+  b /= a;
+  return b;
+}