From: Richard Biener <rguenther@suse.de>
Date: Thu, 2 May 2019 11:17:00 +0000 (+0000)
Subject: re PR tree-optimization/90273 (GCC runs out of memory building Firefox)
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=c27998546ac2291ceffbf1f998f6e46e6b8ad6eb;p=gcc.git

re PR tree-optimization/90273 (GCC runs out of memory building Firefox)

2019-05-02  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/90273
	* tree-ssa-dce.c (eliminate_unnecessary_stmts): Eliminate
	useless debug stmts.

From-SVN: r270791
---

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 720627bc702..1f55cd18210 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2019-05-02  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/90273
+	* tree-ssa-dce.c (eliminate_unnecessary_stmts): Eliminate
+	useless debug stmts.
+
 2019-05-02  Alejandro Martinez  <alejandro.martinezvicente@arm.com>
 
 	* config/aarch64/aarch64-sve.md (<sur>dot_prod<vsi2qi>): Taken from SVE
diff --git a/gcc/tree-ssa-dce.c b/gcc/tree-ssa-dce.c
index c0e122722c0..4853f0bd73e 100644
--- a/gcc/tree-ssa-dce.c
+++ b/gcc/tree-ssa-dce.c
@@ -1237,6 +1237,7 @@ eliminate_unnecessary_stmts (void)
       bb = h.pop ();
 
       /* Remove dead statements.  */
+      auto_bitmap debug_seen;
       for (gsi = gsi_last_bb (bb); !gsi_end_p (gsi); gsi = psi)
 	{
 	  stmt = gsi_stmt (gsi);
@@ -1282,11 +1283,15 @@ eliminate_unnecessary_stmts (void)
 			}
 		    }
 		  if (!dead)
-		    continue;
+		    {
+		      bitmap_clear (debug_seen);
+		      continue;
+		    }
 		}
 	      if (!is_gimple_debug (stmt))
 		something_changed = true;
 	      remove_dead_stmt (&gsi, bb, to_remove_edges);
+	      continue;
 	    }
 	  else if (is_gimple_call (stmt))
 	    {
@@ -1352,6 +1357,18 @@ eliminate_unnecessary_stmts (void)
 		    break;
 		  }
 	    }
+	  else if (gimple_debug_bind_p (stmt))
+	    {
+	      /* We are only keeping the last debug-bind of a
+	         non-DEBUG_EXPR_DECL variable in a series of
+		 debug-bind stmts.  */
+	      tree var = gimple_debug_bind_get_var (stmt);
+	      if (TREE_CODE (var) != DEBUG_EXPR_DECL
+		  && !bitmap_set_bit (debug_seen, DECL_UID (var)))
+		remove_dead_stmt (&gsi, bb, to_remove_edges);
+	      continue;
+	    }
+	  bitmap_clear (debug_seen);
 	}
 
       /* Remove dead PHI nodes.  */