From 7f879c9615a980c3874350e9739bce139c67f322 Mon Sep 17 00:00:00 2001
From: Richard Guenther <rguenther@suse.de>
Date: Fri, 16 Nov 2007 10:10:05 +0000
Subject: [PATCH] re PR tree-optimization/34099 (optimizer problem)

2007-11-16  Richard Guenther  <rguenther@suse.de>

	PR tree-optimization/34099
	* tree-ssa-ccp.c (likely_value): Use a whitelist for operators
	that produce UNDEFINED result if at least one of its operands
	is UNDEFINED.  By default the result is only UNDEFINED if all
	operands are UNDEFINED.

	* g++.dg/torture/pr3499.C: New testcase.
	* gcc.c-torture/execute/pr34099.c: Likewise.

From-SVN: r130222
---
 gcc/ChangeLog                                 |  8 +++
 gcc/testsuite/ChangeLog                       |  6 ++
 gcc/testsuite/g++.dg/torture/pr34099.C        | 25 ++++++++
 gcc/testsuite/gcc.c-torture/execute/pr34099.c | 16 +++++
 gcc/tree-ssa-ccp.c                            | 62 ++++++++++++++++++-
 5 files changed, 114 insertions(+), 3 deletions(-)
 create mode 100644 gcc/testsuite/g++.dg/torture/pr34099.C
 create mode 100644 gcc/testsuite/gcc.c-torture/execute/pr34099.c

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 6db268ff8695..80dac9c59107 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,11 @@
+2007-11-16  Richard Guenther  <rguenther@suse.de>
+
+	PR tree-optimization/34099
+	* tree-ssa-ccp.c (likely_value): Use a whitelist for operators
+	that produce UNDEFINED result if at least one of its operands
+	is UNDEFINED.  By default the result is only UNDEFINED if all
+	operands are UNDEFINED.
+
 2007-11-16  Jakub Jelinek  <jakub@redhat.com>
 
 	PR driver/30460
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 0ef30d2a02e4..9c84667f81fa 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,9 @@
+2007-11-16  Richard Guenther  <rguenther@suse.de>
+
+	PR tree-optimization/34099
+	* g++.dg/torture/pr3499.C: New testcase.
+	* gcc.c-torture/execute/pr34099.c: Likewise.
+
 2007-11-16  Olivier Hainque  <hainque@adacore.com>
 
 	* gnat.dg/release_unc_maxalign.adb: New test.
diff --git a/gcc/testsuite/g++.dg/torture/pr34099.C b/gcc/testsuite/g++.dg/torture/pr34099.C
new file mode 100644
index 000000000000..49fa9cac1ebc
--- /dev/null
+++ b/gcc/testsuite/g++.dg/torture/pr34099.C
@@ -0,0 +1,25 @@
+/* { dg-do run } */
+
+#include <complex>
+
+typedef std::complex<double> NumType;
+
+void
+multiply(NumType a, NumType b, unsigned ac, NumType &ab)
+{
+  NumType s;
+  for (unsigned j=0; j<ac; j++)
+    s = a * b;
+  ab = s;
+}
+extern "C" void abort (void);
+int main()
+{
+  NumType a(1,2), b(3,-2), c;
+  multiply(a, b, 1, c);
+  if (c.real() != 7
+      || c.imag() != 4)
+    abort ();
+  return 0;
+}
+
diff --git a/gcc/testsuite/gcc.c-torture/execute/pr34099.c b/gcc/testsuite/gcc.c-torture/execute/pr34099.c
new file mode 100644
index 000000000000..d6f5ad1f6517
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/execute/pr34099.c
@@ -0,0 +1,16 @@
+int foo (int b, int c)
+{
+  int x;
+  if (b)
+    return x & c;
+  else
+    return 1;
+}
+extern void abort (void);
+int main()
+{
+  if (foo(1, 0) != 0)
+    abort ();
+  return 0;
+}
+
diff --git a/gcc/tree-ssa-ccp.c b/gcc/tree-ssa-ccp.c
index 0fc4b4713b41..fc40449be8db 100644
--- a/gcc/tree-ssa-ccp.c
+++ b/gcc/tree-ssa-ccp.c
@@ -507,7 +507,8 @@ set_lattice_value (tree var, prop_value_t new_val)
 
    If STMT has no operands, then return CONSTANT.
 
-   Else if any operands of STMT are undefined, then return UNDEFINED.
+   Else if undefinedness of operands of STMT cause its value to be
+   undefined, then return UNDEFINED.
 
    Else if any operands of STMT are constants, then return CONSTANT.
 
@@ -516,7 +517,7 @@ set_lattice_value (tree var, prop_value_t new_val)
 static ccp_lattice_t
 likely_value (tree stmt)
 {
-  bool has_constant_operand;
+  bool has_constant_operand, has_undefined_operand, all_undefined_operands;
   stmt_ann_t ann;
   tree use;
   ssa_op_iter iter;
@@ -552,17 +553,72 @@ likely_value (tree stmt)
     return CONSTANT;
 
   has_constant_operand = false;
+  has_undefined_operand = false;
+  all_undefined_operands = true;
   FOR_EACH_SSA_TREE_OPERAND (use, stmt, iter, SSA_OP_USE | SSA_OP_VUSE)
     {
       prop_value_t *val = get_value (use);
 
       if (val->lattice_val == UNDEFINED)
-	return UNDEFINED;
+	has_undefined_operand = true;
+      else
+	all_undefined_operands = false;
 
       if (val->lattice_val == CONSTANT)
 	has_constant_operand = true;
     }
 
+  /* If the operation combines operands like COMPLEX_EXPR make sure to
+     not mark the result UNDEFINED if only one part of the result is
+     undefined.  */
+  if (has_undefined_operand
+      && all_undefined_operands)
+    return UNDEFINED;
+  else if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT
+	   && has_undefined_operand)
+    {
+      switch (TREE_CODE (GIMPLE_STMT_OPERAND (stmt, 1)))
+	{
+	/* Unary operators are handled with all_undefined_operands.  */
+	case PLUS_EXPR:
+	case MINUS_EXPR:
+	case MULT_EXPR:
+	case POINTER_PLUS_EXPR:
+	case TRUNC_DIV_EXPR:
+	case CEIL_DIV_EXPR:
+	case FLOOR_DIV_EXPR:
+	case ROUND_DIV_EXPR:
+	case TRUNC_MOD_EXPR:
+	case CEIL_MOD_EXPR:
+	case FLOOR_MOD_EXPR:
+	case ROUND_MOD_EXPR:
+	case RDIV_EXPR:
+	case EXACT_DIV_EXPR:
+	case LSHIFT_EXPR:
+	case RSHIFT_EXPR:
+	case LROTATE_EXPR:
+	case RROTATE_EXPR:
+	case EQ_EXPR:
+	case NE_EXPR:
+	case LT_EXPR:
+	case GT_EXPR:
+	  /* Not MIN_EXPR, MAX_EXPR.  One VARYING operand may be selected.
+	     Not bitwise operators, one VARYING operand may specify the
+	     result completely.  Not logical operators for the same reason.
+	     Not LE/GE comparisons or unordered comparisons.  Not
+	     COMPLEX_EXPR as one VARYING operand makes the result partly
+	     not UNDEFINED.  */
+	  return UNDEFINED;
+
+	default:
+	  ;
+	}
+    }
+  /* If there was an UNDEFINED operand but the result may be not UNDEFINED
+     fall back to VARYING even if there were CONSTANT operands.  */
+  if (has_undefined_operand)
+    return VARYING;
+
   if (has_constant_operand
       /* We do not consider virtual operands here -- load from read-only
 	 memory may have only VARYING virtual operands, but still be