The attached change fixes PR target/79027 On gcc-8 and gcc-7, under some
conditions that are
a bit hard to reproduce, we get a floating point exception when regcprop.c
tries to change a SImode value
to BLKmode. The attached patch to pa_cannot_change_mode_class reject such
changes. As a result,
fold-const.c compiles successfully.
The bug is latent in all active branches.
Tested on hppa-unknown-linux-gnu and hppa2.0w-hp-hpux11.11 trunk. Committed to
trunk.
Dave
--
John David Anglin dave.ang...@bell.net
2017-05-10 John David Anglin <dang...@gcc.gnu.org>
PR target/79027
* config/pa/pa.c (pa_cannot_change_mode_class): Reject changes to/from
modes with zero size. Enhance comment.
Index: config/pa/pa.c
===================================================================
--- config/pa/pa.c (revision 247726)
+++ config/pa/pa.c (working copy)
@@ -9962,19 +9981,23 @@
if (from == to)
return false;
+ if (GET_MODE_SIZE (from) == GET_MODE_SIZE (to))
+ return false;
+
+ /* Reject changes to/from modes with zero size. */
+ if (!GET_MODE_SIZE (from) || !GET_MODE_SIZE (to))
+ return true;
+
/* Reject changes to/from complex and vector modes. */
if (COMPLEX_MODE_P (from) || VECTOR_MODE_P (from)
|| COMPLEX_MODE_P (to) || VECTOR_MODE_P (to))
return true;
- if (GET_MODE_SIZE (from) == GET_MODE_SIZE (to))
- return false;
-
- /* There is no way to load QImode or HImode values directly from
- memory. SImode loads to the FP registers are not zero extended.
- On the 64-bit target, this conflicts with the definition of
- LOAD_EXTEND_OP. Thus, we can't allow changing between modes
- with different sizes in the floating-point registers. */
+ /* There is no way to load QImode or HImode values directly from memory
+ to a FP register. SImode loads to the FP registers are not zero
+ extended. On the 64-bit target, this conflicts with the definition
+ of LOAD_EXTEND_OP. Thus, we can't allow changing between modes with
+ different sizes in the floating-point registers. */
if (MAYBE_FP_REG_CLASS_P (rclass))
return true;
