[gcc(refs/vendors/redhat/heads/gcc-8-branch)] tree-optimization/94163 constrain alignment set by PRE

[Jakub Jelinek <jakub@gcc.gnu.org>]

https://gcc.gnu.org/g:96757464c3d07e727767fe11d198c07151971135

commit 96757464c3d07e727767fe11d198c07151971135
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 45670c3e20d..2f80eff858a 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.
+
 2019-03-13  Eric Botcazou  <ebotcazou@adacore.com>
 
 	PR rtl-optimization/94119
diff --git a/gcc/tree-ssa-pre.c b/gcc/tree-ssa-pre.c
index 5f9dc50eef6..7f7e4173302 100644
--- a/gcc/tree-ssa-pre.c
+++ b/gcc/tree-ssa-pre.c
@@ -2797,7 +2797,8 @@ 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);
 	    }