re PR rtl-optimization/49472 (Compiler segfault on valid code)

	PR rtl-optimization/49472
	* simplify-rtx.c (simplify_unary_operation_1) <case NEG>: When
	negating MULT, negate the second operand instead of first.
	(simplify_binary_operation_1) <case MULT>: If one operand is
	a NEG and the other is MULT, don't attempt to optimize by
	negation of the MULT operand if it only moves the NEG operation
	around.

	* gfortran.dg/pr49472.f90: New test.

From-SVN: r175821

gcc/ChangeLog

 2011-07-04  Jakub Jelinek  <jakub@redhat.com>
 
+	PR rtl-optimization/49472
+	* simplify-rtx.c (simplify_unary_operation_1) <case NEG>: When
+	negating MULT, negate the second operand instead of first.
+	(simplify_binary_operation_1) <case MULT>: If one operand is
+	a NEG and the other is MULT, don't attempt to optimize by
+	negation of the MULT operand if it only moves the NEG operation
+	around.
+
 	PR debug/49602
 	* tree-into-ssa.c (rewrite_debug_stmt_uses): Disregard
 	get_current_def return value if it can't be trusted to be

gcc/simplify-rtx.c

@@ -686,13 +686,13 @@ simplify_unary_operation_1 (enum rtx_code code, enum machine_mode mode, rtx op)
 	  return simplify_gen_binary (MINUS, mode, temp, XEXP (op, 1));
 	}
 
-      /* (neg (mult A B)) becomes (mult (neg A) B).
+      /* (neg (mult A B)) becomes (mult A (neg B)).
 	 This works even for floating-point values.  */
       if (GET_CODE (op) == MULT
 	  && !HONOR_SIGN_DEPENDENT_ROUNDING (mode))
 	{
-	  temp = simplify_gen_unary (NEG, mode, XEXP (op, 0), mode);
-	  return simplify_gen_binary (MULT, mode, temp, XEXP (op, 1));
+	  temp = simplify_gen_unary (NEG, mode, XEXP (op, 1), mode);
+	  return simplify_gen_binary (MULT, mode, XEXP (op, 0), temp);
 	}
 
       /* NEG commutes with ASHIFT since it is multiplication.  Only do
@@ -2271,12 +2271,34 @@ simplify_binary_operation_1 (enum rtx_code code, enum machine_mode mode,
       if (GET_CODE (op0) == NEG)
 	{
 	  rtx temp = simplify_unary_operation (NEG, mode, op1, mode);
+	  /* If op1 is a MULT as well and simplify_unary_operation
+	     just moved the NEG to the second operand, simplify_gen_binary
+	     below could through simplify_associative_operation move
+	     the NEG around again and recurse endlessly.  */
+	  if (temp
+	      && GET_CODE (op1) == MULT
+	      && GET_CODE (temp) == MULT
+	      && XEXP (op1, 0) == XEXP (temp, 0)
+	      && GET_CODE (XEXP (temp, 1)) == NEG
+	      && XEXP (op1, 1) == XEXP (XEXP (temp, 1), 0))
+	    temp = NULL_RTX;
 	  if (temp)
 	    return simplify_gen_binary (MULT, mode, XEXP (op0, 0), temp);
 	}
       if (GET_CODE (op1) == NEG)
 	{
 	  rtx temp = simplify_unary_operation (NEG, mode, op0, mode);
+	  /* If op0 is a MULT as well and simplify_unary_operation
+	     just moved the NEG to the second operand, simplify_gen_binary
+	     below could through simplify_associative_operation move
+	     the NEG around again and recurse endlessly.  */
+	  if (temp
+	      && GET_CODE (op0) == MULT
+	      && GET_CODE (temp) == MULT
+	      && XEXP (op0, 0) == XEXP (temp, 0)
+	      && GET_CODE (XEXP (temp, 1)) == NEG
+	      && XEXP (op0, 1) == XEXP (XEXP (temp, 1), 0))
+	    temp = NULL_RTX;
 	  if (temp)
 	    return simplify_gen_binary (MULT, mode, temp, XEXP (op1, 0));
 	}

gcc/testsuite/ChangeLog

 2011-07-04  Jakub Jelinek  <jakub@redhat.com>
 
+	PR rtl-optimization/49472
+	* gfortran.dg/pr49472.f90: New test.
+
 	PR debug/49602
 	* gcc.dg/pr49602.c: New test.
 

gcc/testsuite/gfortran.dg/pr49472.f90

+! PR rtl-optimization/49472
+! { dg-do compile }
+! { dg-options "-O -fcompare-debug -ffast-math" }
+subroutine pr49472
+  integer, parameter :: n = 3
+  real(8) :: a, b, c, d, e (n+1)
+  integer :: i
+  do i=2, (n+1)
+    b = 1. / ((i - 1.5d0) * 1.)
+    c = b * a
+    d = -b * c / (1. + b * b) ** 1.5d0
+    e(i) = d
+  end do
+  call dummy (e)
+end subroutine