Fix PR43402: miscompile of libicu

[Michael Matz <matz at suse dot de>]

Hi,

the fix for pr43186 made cfgcleanup look through single-argument PHI 
nodes.  That's fine except that during cfgcleanup we might have some SSA 
names registered for update (we run update_ssa only after cfgcleanup).  We 
can't look through such SSA names.

This fixes the miscompile and still make pr43186 pass.  Regstrapping on 
x86_64 in progress, okay for trunk?


Ciao,
Michael.
-- 
	PR tree-optimization/43402
	* tree-cfgcleanup.c (cleanup_control_expr_graph): Don't follow
	PHI chains of ssa names registered for update.

testsuite/
	* gcc.dg/pr43402.c: New testcase.

Index: tree-cfgcleanup.c
===================================================================
--- tree-cfgcleanup.c	(revision 157458)
+++ tree-cfgcleanup.c	(working copy)
@@ -103,20 +103,28 @@ cleanup_control_expr_graph (basic_block
 	    /* For conditions try harder and lookup single-argument
 	       PHI nodes.  Only do so from the same basic-block though
 	       as other basic-blocks may be dead already.  */
-	    if (TREE_CODE (lhs) == SSA_NAME)
+	    if (TREE_CODE (lhs) == SSA_NAME
+		&& !name_registered_for_update_p (lhs))
 	      {
 		gimple def_stmt = SSA_NAME_DEF_STMT (lhs);
 		if (gimple_code (def_stmt) == GIMPLE_PHI
 		    && gimple_phi_num_args (def_stmt) == 1
-		    && gimple_bb (def_stmt) == gimple_bb (stmt))
+		    && gimple_bb (def_stmt) == gimple_bb (stmt)
+		    && (TREE_CODE (PHI_ARG_DEF (def_stmt, 0)) != SSA_NAME
+			|| !name_registered_for_update_p (PHI_ARG_DEF (def_stmt,
+								       0))))
 		  lhs = PHI_ARG_DEF (def_stmt, 0);
 	      }
-	    if (TREE_CODE (rhs) == SSA_NAME)
+	    if (TREE_CODE (rhs) == SSA_NAME
+		&& !name_registered_for_update_p (rhs))
 	      {
 		gimple def_stmt = SSA_NAME_DEF_STMT (rhs);
 		if (gimple_code (def_stmt) == GIMPLE_PHI
 		    && gimple_phi_num_args (def_stmt) == 1
-		    && gimple_bb (def_stmt) == gimple_bb (stmt))
+		    && gimple_bb (def_stmt) == gimple_bb (stmt)
+		    && (TREE_CODE (PHI_ARG_DEF (def_stmt, 0)) != SSA_NAME
+			|| !name_registered_for_update_p (PHI_ARG_DEF (def_stmt,
+								       0))))
 		  rhs = PHI_ARG_DEF (def_stmt, 0);
 	      }
 	    val = fold_binary_loc (loc, gimple_cond_code (stmt),
Index: testsuite/gcc.dg/pr43402.c
===================================================================
--- testsuite/gcc.dg/pr43402.c	(revision 0)
+++ testsuite/gcc.dg/pr43402.c	(revision 0)
@@ -0,0 +1,58 @@
+/* { dg-do run } */
+/* { dg-options "-O1 -fno-inline" } */
+extern void abort (void);
+
+static int something;
+
+static int * converterData[2]={
+    &something, &something,
+};
+
+static struct {
+  const char *name;
+  int type;
+} const cnvNameType[] = {
+  { "bocu1", 1 },
+  { "utf7", 1 },
+  { "utf8", 1 }
+};
+
+
+const int * getAlgorithmicTypeFromName(const char *realName);
+const int *
+getAlgorithmicTypeFromName(const char *realName)
+{
+    unsigned mid, start, limit;
+    unsigned lastMid;
+    int result;
+    start = 0;
+    limit = sizeof(cnvNameType)/sizeof(cnvNameType[0]);
+    mid = limit;
+    lastMid = 0xffffffff;
+
+    for (;;) {
+        mid = (start + limit) / 2;
+        if (lastMid == mid) {   /* Have we moved? */
+            break;  /* We haven't moved, and it wasn't found. */
+        }
+        lastMid = mid;
+        result = __builtin_strcmp(realName, cnvNameType[mid].name);
+
+        if (result < 0) {
+            limit = mid;
+        } else if (result > 0) {
+            start = mid;
+        } else {
+            return converterData[cnvNameType[mid].type];
+        }
+    }
+
+    return 0;
+}
+
+int main (void)
+{
+  if (!getAlgorithmicTypeFromName ("utf8"))
+    abort ();
+  return 0;
+}