[gcc/devel/c++-modules] tree-optimization/94163 constrain alignment set by PRE

[gcc/devel/c++-modules] tree-optimization/94163 constrain alignment set by PRE

[Nathan Sidwell]

https://gcc.gnu.org/g:3604480a6fe493c51d6ebd53d9b1abeebbbb828f

commit 3604480a6fe493c51d6ebd53d9b1abeebbbb828f
Author: Richard Biener <rguenther@suse.de>
Date:   Fri Mar 13 13:56:26 2020 +0100

    tree-optimization/94163 constrain alignment set by PRE
    
    This avoids HWI -> unsigned truncation to end up with zero alignment
    which set_ptr_info_alignment ICEs on.
    
    2020-03-13  Richard Biener  <rguenther@suse.de>
    
            PR tree-optimization/94163
            * tree-ssa-pre.c (create_expression_by_pieces): Check
            whether alignment would be zero.

Diff:
---
 gcc/ChangeLog      | 6 ++++++
 gcc/tree-ssa-pre.c | 3 ++-
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 679296ffcac..18745fb6a15 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2020-03-13  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/94163
+	* tree-ssa-pre.c (create_expression_by_pieces): Check
+	whether alignment would be zero.
+
 2020-03-13  Martin Liska  <mliska@suse.cz>
 
 	PR lto/94157
diff --git a/gcc/tree-ssa-pre.c b/gcc/tree-ssa-pre.c
index 29987d840fd..0c1654f3580 100644
--- a/gcc/tree-ssa-pre.c
+++ b/gcc/tree-ssa-pre.c
@@ -2815,7 +2815,8 @@ create_expression_by_pieces (basic_block block, pre_expr expr,
 	      unsigned HOST_WIDE_INT hmisalign
 		= args.length () == 3 ? tree_to_uhwi (args[2]) : 0;
 	      if ((halign & (halign - 1)) == 0
-		  && (hmisalign & ~(halign - 1)) == 0)
+		  && (hmisalign & ~(halign - 1)) == 0
+		  && (unsigned int)halign != 0)
 		set_ptr_info_alignment (get_ptr_info (forcedname),
 					halign, hmisalign);
 	    }