+2003-07-31 Roger Sayle <roger@eyesopen.com>
+
+ * fold-const.c (fold <MULT_EXPR>): Optimize both x*pow(x,c) and
+ pow(x,c)*x as pow(x,c+1) for constant values c. Optimize x*x
+ as pow(x,2.0) when the latter will be expanded back into x*x.
+ (fold <RDIV_EXPR>): Optimize pow(x,c)/x as pow(x,c-1).
+ * builtins.c (expand_builtin_pow): Ignore flag_errno_math as
+ pow can never set errno when used with an integer exponent.
+ Always use expand_powi when exponent is -1, 0, 1 or 2.
+ (fold_builtin): Don't rewrite pow(x,2.0) as x*x nor pow(x,-2.0)
+ as 1.0/(x*x). This avoids unbounded recursion as we now prefer
+ the pow forms of these expressions.
+
2003-07-31 Geoffrey Keating <geoffk@apple.com>
* Makefile.in (libexecdir): New.
arg0 = TREE_VALUE (arglist);
arg1 = TREE_VALUE (TREE_CHAIN (arglist));
- if (flag_unsafe_math_optimizations
- && ! flag_errno_math
- && ! optimize_size
- && TREE_CODE (arg1) == REAL_CST
+ if (TREE_CODE (arg1) == REAL_CST
&& ! TREE_CONSTANT_OVERFLOW (arg1))
{
REAL_VALUE_TYPE cint;
c = TREE_REAL_CST (arg1);
n = real_to_integer (&c);
real_from_integer (&cint, VOIDmode, n, n < 0 ? -1 : 0, 0);
- if (real_identical (&c, &cint)
- && powi_cost (n) <= POWI_MAX_MULTS)
+ if (real_identical (&c, &cint))
{
- enum machine_mode mode = TYPE_MODE (TREE_TYPE (exp));
- rtx op = expand_expr (arg0, subtarget, VOIDmode, 0);
- op = force_reg (mode, op);
- return expand_powi (op, mode, n);
+ /* If the exponent is -1, 0, 1 or 2, then expand_powi is exact.
+ Otherwise, check the number of multiplications required.
+ Note that pow never sets errno for an integer exponent. */
+ if ((n >= -1 && n <= 2)
+ || (flag_unsafe_math_optimizations
+ && ! optimize_size
+ && powi_cost (n) <= POWI_MAX_MULTS))
+ {
+ enum machine_mode mode = TYPE_MODE (TREE_TYPE (exp));
+ rtx op = expand_expr (arg0, subtarget, VOIDmode, 0);
+ op = force_reg (mode, op);
+ return expand_powi (op, mode, n);
+ }
}
}
return expand_builtin_mathfn_2 (exp, target, NULL_RTX);
build_real (type, dconst1),
arg0));
- /* Optimize pow(x,2.0) = x*x. */
- if (REAL_VALUES_EQUAL (c, dconst2)
- && (*lang_hooks.decls.global_bindings_p) () == 0
- && ! CONTAINS_PLACEHOLDER_P (arg0))
- {
- arg0 = save_expr (arg0);
- return fold (build (MULT_EXPR, type, arg0, arg0));
- }
-
- /* Optimize pow(x,-2.0) = 1.0/(x*x). */
- if (flag_unsafe_math_optimizations
- && REAL_VALUES_EQUAL (c, dconstm2)
- && (*lang_hooks.decls.global_bindings_p) () == 0
- && ! CONTAINS_PLACEHOLDER_P (arg0))
- {
- arg0 = save_expr (arg0);
- return fold (build (RDIV_EXPR, type,
- build_real (type, dconst1),
- fold (build (MULT_EXPR, type,
- arg0, arg0))));
- }
-
/* Optimize pow(x,0.5) = sqrt(x). */
if (flag_unsafe_math_optimizations
&& REAL_VALUES_EQUAL (c, dconsthalf))
return build_function_call_expr (sinfn,
TREE_OPERAND (arg0, 1));
}
+
+ /* Optimize x*pow(x,c) as pow(x,c+1). */
+ if (fcode1 == BUILT_IN_POW
+ || fcode1 == BUILT_IN_POWF
+ || fcode1 == BUILT_IN_POWL)
+ {
+ tree arg10 = TREE_VALUE (TREE_OPERAND (arg1, 1));
+ tree arg11 = TREE_VALUE (TREE_CHAIN (TREE_OPERAND (arg1,
+ 1)));
+ if (TREE_CODE (arg11) == REAL_CST
+ && ! TREE_CONSTANT_OVERFLOW (arg11)
+ && operand_equal_p (arg0, arg10, 0))
+ {
+ tree powfn = TREE_OPERAND (TREE_OPERAND (arg1, 0), 0);
+ REAL_VALUE_TYPE c;
+ tree arg, arglist;
+
+ c = TREE_REAL_CST (arg11);
+ real_arithmetic (&c, PLUS_EXPR, &c, &dconst1);
+ arg = build_real (type, c);
+ arglist = build_tree_list (NULL_TREE, arg);
+ arglist = tree_cons (NULL_TREE, arg0, arglist);
+ return build_function_call_expr (powfn, arglist);
+ }
+ }
+
+ /* Optimize pow(x,c)*x as pow(x,c+1). */
+ if (fcode0 == BUILT_IN_POW
+ || fcode0 == BUILT_IN_POWF
+ || fcode0 == BUILT_IN_POWL)
+ {
+ tree arg00 = TREE_VALUE (TREE_OPERAND (arg0, 1));
+ tree arg01 = TREE_VALUE (TREE_CHAIN (TREE_OPERAND (arg0,
+ 1)));
+ if (TREE_CODE (arg01) == REAL_CST
+ && ! TREE_CONSTANT_OVERFLOW (arg01)
+ && operand_equal_p (arg1, arg00, 0))
+ {
+ tree powfn = TREE_OPERAND (TREE_OPERAND (arg0, 0), 0);
+ REAL_VALUE_TYPE c;
+ tree arg, arglist;
+
+ c = TREE_REAL_CST (arg01);
+ real_arithmetic (&c, PLUS_EXPR, &c, &dconst1);
+ arg = build_real (type, c);
+ arglist = build_tree_list (NULL_TREE, arg);
+ arglist = tree_cons (NULL_TREE, arg1, arglist);
+ return build_function_call_expr (powfn, arglist);
+ }
+ }
+
+ /* Optimize x*x as pow(x,2.0), which is expanded as x*x. */
+ if (! optimize_size
+ && operand_equal_p (arg0, arg1, 0))
+ {
+ tree powfn;
+
+ if (type == double_type_node)
+ powfn = implicit_built_in_decls[BUILT_IN_POW];
+ else if (type == float_type_node)
+ powfn = implicit_built_in_decls[BUILT_IN_POWF];
+ else if (type == long_double_type_node)
+ powfn = implicit_built_in_decls[BUILT_IN_POWL];
+ else
+ powfn = NULL_TREE;
+
+ if (powfn)
+ {
+ tree arg = build_real (type, dconst2);
+ tree arglist = build_tree_list (NULL_TREE, arg);
+ arglist = tree_cons (NULL_TREE, arg0, arglist);
+ return build_function_call_expr (powfn, arglist);
+ }
+ }
}
}
goto associate;
tmp));
}
}
+
+ /* Optimize pow(x,c)/x as pow(x,c-1). */
+ if (fcode0 == BUILT_IN_POW
+ || fcode0 == BUILT_IN_POWF
+ || fcode0 == BUILT_IN_POWL)
+ {
+ tree arg00 = TREE_VALUE (TREE_OPERAND (arg0, 1));
+ tree arg01 = TREE_VALUE (TREE_CHAIN (TREE_OPERAND (arg0, 1)));
+ if (TREE_CODE (arg01) == REAL_CST
+ && ! TREE_CONSTANT_OVERFLOW (arg01)
+ && operand_equal_p (arg1, arg00, 0))
+ {
+ tree powfn = TREE_OPERAND (TREE_OPERAND (arg0, 0), 0);
+ REAL_VALUE_TYPE c;
+ tree arg, arglist;
+
+ c = TREE_REAL_CST (arg01);
+ real_arithmetic (&c, MINUS_EXPR, &c, &dconst1);
+ arg = build_real (type, c);
+ arglist = build_tree_list (NULL_TREE, arg);
+ arglist = tree_cons (NULL_TREE, arg1, arglist);
+ return build_function_call_expr (powfn, arglist);
+ }
+ }
}
goto binary;
+2003-07-31 Roger Sayle <roger@eyesopen.com>
+
+ * gcc.dg/builtins-27.c: New test case.
+
2003-07-31 Jakub Jelinek <jakub@redhat.com>
* gcc.dg/tls/opt-7.c: New test.
--- /dev/null
+/* Copyright (C) 2003 Free Software Foundation.
+
+ Check that constant folding of built-in math functions doesn't
+ break anything and produces the expected results.
+
+ Written by Roger Sayle, 29th July 2003. */
+
+/* { dg-do link } */
+/* { dg-options "-O2 -ffast-math" } */
+
+extern void link_error(void);
+
+extern double pow(double,double);
+
+void test(double x)
+{
+ if (pow(x,2.0) != x*x)
+ link_error ();
+
+ if (x*pow(x,2.0) != pow(x,3.0))
+ link_error ();
+
+ if (pow(x,2.0)*x != pow(x,3.0))
+ link_error ();
+
+ if (pow(x,3.0) != x*x*x)
+ link_error ();
+
+ if (pow(x,2.0)*x != x*x*x)
+ link_error ();
+
+ if (x*pow(x,2.0) != x*x*x)
+ link_error ();
+
+ if (pow(x,3.0)/x != pow(x,2.0))
+ link_error ();
+
+ if (pow(x,3.0)/x != x*x)
+ link_error ();
+}
+
+int main()
+{
+ test (2.0);
+ return 0;
+}
+
projects / platform / upstream / gcc.git / commitdiff