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[Committed] hppa: Reject changes to/from modes with zero size in pa_cannot_change_mode_class

Message ID 31F1B830-5BE1-4F40-9617-33869C759521@bell.net
State New
Headers show

Commit Message

John David Anglin May 10, 2017, 11:05 p.m. UTC 
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.anglin@bell.net
2017-05-10  John David Anglin  <danglin@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.
diff mbox

Patch

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;