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[PATCH]: Add some more builtins opts for sqrt/cbrt


This patch adds a few more builtin optimizations for sqrt and cbrt.
The new transformations are:

sqrt(Nroot(x)) -> pow(x,1/(2*N))  (where Nroot is either sqrt or cbrt)
cbrt(N) -> N                      (for N == {0,1,-1})
cbrt(expN(x)) -> expN(x/3)
cbrt(sqrt(x)) -> pow(x,1/6)
cbrt(x)*cbrt(y) -> cbrt(x*y)

I didn't do cbrt(cbrt(x)), cbrt(pow(x,y)) and pow(cbrt(x),y) into
plain pow because I believe all of these would succeed with innocuous
negative values of x but might fail if tranformed into just pow.  I'll
do these later by checking if x is nonnegative or y is a multiple of
three.

Tested on sparc-sun-solaris2.7, no regressions and the new cases pass.

Ok for mainline?

		Thanks,
		--Kaveh


2004-03-12  Kaveh R. Ghazi  <ghazi@caip.rutgers.edu>

	* builtins.c (fold_builtin): Add new builtin optimizations for
	sqrt and/or cbrt.
	* fold-const.c (fold): Likewise.

testsuite:
	* gcc.dg/torture/builtin-explog-1.c: Add new cases.
	* gcc.dg/torture/builtin-math-1.c: Likewise.
	* builtin-power-1.c: New test.

diff -rup orig/egcc-CVS20040310/gcc/builtins.c egcc-CVS20040310/gcc/builtins.c
--- orig/egcc-CVS20040310/gcc/builtins.c	2004-03-10 20:02:07.000000000 -0500
+++ egcc-CVS20040310/gcc/builtins.c	2004-03-11 18:03:17.721038000 -0500
@@ -6748,6 +6748,29 @@ fold_builtin (tree exp)
 	      return build_function_call_expr (expfn, arglist);
 	    }
 
+	  /* Optimize sqrt(Nroot(x)) -> pow(x,1/(2*N)).  */
+	  if (flag_unsafe_math_optimizations && BUILTIN_ROOT_P (fcode))
+	    {
+	      tree powfn = mathfn_built_in (type, BUILT_IN_POW);
+	      
+	      if (powfn)
+	        {
+		  tree arg0 = TREE_VALUE (TREE_OPERAND (arg, 1));
+		  tree tree_root;
+		  /* The inner root was either sqrt or cbrt.  */
+		  REAL_VALUE_TYPE dconstroot =
+		    BUILTIN_SQRT_P (fcode) ? dconsthalf : dconstthird;
+		  
+		  /* Adjust for the outer root.  */
+		  dconstroot.exp--;
+		  dconstroot = real_value_truncate (TYPE_MODE (type), dconstroot);
+		  tree_root = build_real (type, dconstroot);
+		  arglist = tree_cons (NULL_TREE, arg0,
+				       build_tree_list (NULL_TREE, tree_root));
+		  return build_function_call_expr (powfn, arglist);
+		}
+	    }
+
 	  /* Optimize sqrt(pow(x,y)) = pow(x,y*0.5).  */
 	  if (flag_unsafe_math_optimizations
 	      && (fcode == BUILT_IN_POW
@@ -6766,6 +6789,56 @@ fold_builtin (tree exp)
 	}
       break;
 
+    case BUILT_IN_CBRT:
+    case BUILT_IN_CBRTF:
+    case BUILT_IN_CBRTL:
+      if (validate_arglist (arglist, REAL_TYPE, VOID_TYPE))
+	{
+	  tree arg = TREE_VALUE (arglist);
+	  const enum built_in_function fcode = builtin_mathfn_code (arg);
+
+	  /* Optimize cbrt of constant value.  */
+	  if (real_zerop (arg) || real_onep (arg) || real_minus_onep (arg))
+	    return arg;
+
+	  /* Optimize cbrt(expN(x)) -> expN(x/3).  */
+	  if (flag_unsafe_math_optimizations && BUILTIN_EXPONENT_P (fcode))
+	    {
+	      tree expfn = TREE_OPERAND (TREE_OPERAND (arg, 0), 0);
+	      const REAL_VALUE_TYPE third_trunc =
+		real_value_truncate (TYPE_MODE (type), dconstthird);
+	      arg = fold (build (MULT_EXPR, type,
+				 TREE_VALUE (TREE_OPERAND (arg, 1)),
+				 build_real (type, third_trunc)));
+	      arglist = build_tree_list (NULL_TREE, arg);
+	      return build_function_call_expr (expfn, arglist);
+	    }
+
+	  /* Optimize cbrt(sqrt(x)) -> pow(x,1/6).  */
+	  /* We don't optimize cbrt(cbrt(x)) -> pow(x,1/9) because if
+             x is negative pow will error but cbrt won't.  */
+	  if (flag_unsafe_math_optimizations && BUILTIN_SQRT_P (fcode))
+	    {
+	      tree powfn = mathfn_built_in (type, BUILT_IN_POW);
+
+	      if (powfn)
+	        {
+		  tree arg0 = TREE_VALUE (TREE_OPERAND (arg, 1));
+		  tree tree_root;
+		  REAL_VALUE_TYPE dconstroot = dconstthird;
+
+		  dconstroot.exp--;
+		  dconstroot = real_value_truncate (TYPE_MODE (type), dconstroot);
+		  tree_root = build_real (type, dconstroot);
+		  arglist = tree_cons (NULL_TREE, arg0,
+				       build_tree_list (NULL_TREE, tree_root));
+		  return build_function_call_expr (powfn, arglist);
+		}
+	      
+	    }
+	}
+      break;
+
     case BUILT_IN_SIN:
     case BUILT_IN_SINF:
     case BUILT_IN_SINL:
diff -rup orig/egcc-CVS20040310/gcc/fold-const.c egcc-CVS20040310/gcc/fold-const.c
--- orig/egcc-CVS20040310/gcc/fold-const.c	2004-03-10 13:13:01.000000000 -0500
+++ egcc-CVS20040310/gcc/fold-const.c	2004-03-11 13:17:27.744332000 -0500
@@ -6422,23 +6422,24 @@ fold (tree expr)
 	      enum built_in_function fcode0 = builtin_mathfn_code (arg0);
 	      enum built_in_function fcode1 = builtin_mathfn_code (arg1);
 
-	      /* Optimizations of sqrt(...)*sqrt(...).  */
-	      if (fcode0 == fcode1 && BUILTIN_SQRT_P (fcode0))
+	      /* Optimizations of root(...)*root(...).  */
+	      if (fcode0 == fcode1 && BUILTIN_ROOT_P (fcode0))
 		{
-		  tree sqrtfn, arg, arglist;
+		  tree rootfn, arg, arglist;
 		  tree arg00 = TREE_VALUE (TREE_OPERAND (arg0, 1));
 		  tree arg10 = TREE_VALUE (TREE_OPERAND (arg1, 1));
 
 		  /* Optimize sqrt(x)*sqrt(x) as x.  */
-		  if (operand_equal_p (arg00, arg10, 0)
+		  if (BUILTIN_SQRT_P (fcode0)
+		      && operand_equal_p (arg00, arg10, 0)
 		      && ! HONOR_SNANS (TYPE_MODE (type)))
 		    return arg00;
 
-	          /* Optimize sqrt(x)*sqrt(y) as sqrt(x*y).  */
-		  sqrtfn = TREE_OPERAND (TREE_OPERAND (arg0, 0), 0);
+	          /* Optimize root(x)*root(y) as root(x*y).  */
+		  rootfn = TREE_OPERAND (TREE_OPERAND (arg0, 0), 0);
 		  arg = fold (build (MULT_EXPR, type, arg00, arg10));
 		  arglist = build_tree_list (NULL_TREE, arg);
-		  return build_function_call_expr (sqrtfn, arglist);
+		  return build_function_call_expr (rootfn, arglist);
 		}
 
 	      /* Optimize expN(x)*expN(y) as expN(x+y).  */
diff -rup orig/egcc-CVS20040310/gcc/testsuite/gcc.dg/torture/builtin-explog-1.c egcc-CVS20040310/gcc/testsuite/gcc.dg/torture/builtin-explog-1.c
--- orig/egcc-CVS20040310/gcc/testsuite/gcc.dg/torture/builtin-explog-1.c	2004-03-06 12:53:57.000000000 -0500
+++ egcc-CVS20040310/gcc/testsuite/gcc.dg/torture/builtin-explog-1.c	2004-03-11 18:56:30.834742000 -0500
@@ -1,4 +1,4 @@
-/* Copyright (C) 2003  Free Software Foundation.
+/* Copyright (C) 2003, 2004  Free Software Foundation.
 
    Verify that built-in math function constant folding of log & exp is
    correctly performed by the compiler.
@@ -119,6 +119,17 @@ void test(double d1, double d2, float f1
   LOG_CBRT(log2);
   LOG_CBRT(log10);
   
+  /* Test cbrt(expN(x)) -> expN(x/3).  */
+#define CBRT_EXP(EXP) \
+ extern void link_failure_cbrt_##EXP(void); \
+ if (cbrt(EXP(d1)) != EXP(d1/3.0) || cbrtf(EXP##f(f1)) != EXP##f(f1/3.0F) \
+  || cbrtl(EXP##l(ld1)) != EXP##l(ld1/3.0L)) link_failure_cbrt_##EXP()
+    
+  CBRT_EXP(exp);
+  CBRT_EXP(exp2);
+  CBRT_EXP(exp10);
+  CBRT_EXP(pow10);
+  
   /* Test logN(pow(x,y)) -> y*logN(x).  */
 #define LOG_POW(LOG, POW) \
  extern void link_failure_##LOG##_##POW(void); \
diff -rup orig/egcc-CVS20040310/gcc/testsuite/gcc.dg/torture/builtin-math-1.c egcc-CVS20040310/gcc/testsuite/gcc.dg/torture/builtin-math-1.c
--- orig/egcc-CVS20040310/gcc/testsuite/gcc.dg/torture/builtin-math-1.c	2003-08-02 15:09:54.000000000 -0400
+++ egcc-CVS20040310/gcc/testsuite/gcc.dg/torture/builtin-math-1.c	2004-03-11 18:56:25.215208000 -0500
@@ -1,4 +1,4 @@
-/* Copyright (C) 2002, 2003  Free Software Foundation.
+/* Copyright (C) 2002, 2003, 2004  Free Software Foundation.
 
    Verify that built-in math function constant folding of constant
    arguments is correctly performed by the compiler.
@@ -18,6 +18,15 @@ void test (float f, double d, long doubl
   if (sqrt (1.0) != 1.0)
     link_error ();
 
+  if (cbrt (0.0) != 0.0)
+    link_error ();
+
+  if (cbrt (1.0) != 1.0)
+    link_error ();
+
+  if (cbrt (-1.0) != -1.0)
+    link_error ();
+
   if (exp (0.0) != 1.0)
     link_error ();
 
@@ -55,6 +64,15 @@ void test (float f, double d, long doubl
   if (sqrtf (1.0F) != 1.0F)
     link_error ();
 
+  if (cbrtf (0.0F) != 0.0F)
+    link_error ();
+
+  if (cbrtf (1.0F) != 1.0F)
+    link_error ();
+
+  if (cbrtf (-1.0F) != -1.0F)
+    link_error ();
+
   if (expf (0.0F) != 1.0F)
     link_error ();
 
@@ -92,6 +110,15 @@ void test (float f, double d, long doubl
   if (sqrtl (1.0L) != 1.0L)
     link_error ();
 
+  if (cbrtl (0.0L) != 0.0L)
+    link_error ();
+
+  if (cbrtl (1.0L) != 1.0L)
+    link_error ();
+
+  if (cbrtl (-1.0L) != -1.0L)
+    link_error ();
+
   if (expl (0.0L) != 1.0L)
     link_error ();
 
diff -rup orig/egcc-CVS20040310/gcc/testsuite/gcc.dg/torture/builtin-power-1.c egcc-CVS20040310/gcc/testsuite/gcc.dg/torture/builtin-power-1.c
--- orig/egcc-CVS20040310/gcc/testsuite/gcc.dg/torture/builtin-power-1.c	2004-03-11 18:14:10.341709000 -0500
+++ egcc-CVS20040310/gcc/testsuite/gcc.dg/torture/builtin-power-1.c	2004-03-11 18:56:03.906846000 -0500
@@ -0,0 +1,105 @@
+/* Copyright (C) 2004  Free Software Foundation.
+
+   Verify that built-in folding of various math "power" functions is
+   correctly performed by the compiler.
+
+   Written by Kaveh Ghazi, 2004-03-11.  */
+
+/* { dg-do link } */
+/* { dg-options "-ffast-math" } */
+
+#include "../builtins-config.h"
+
+#ifdef HAVE_C99_RUNTIME
+#define C99CODE(CODE) CODE
+#else
+#define C99CODE(CODE) 0
+#endif
+
+#define PROTOTYPE(FN) extern double FN(double); extern float FN##f(float); \
+  extern long double FN##l(long double);
+#define PROTOTYPE2(FN) extern double FN(double, double); \
+  extern float FN##f(float, float); \
+  extern long double FN##l(long double, long double);
+
+PROTOTYPE(sqrt)
+PROTOTYPE(cbrt)
+PROTOTYPE2(pow)
+
+void test(double d1, double d2, double d3,
+	  float f1, float f2, float f3,
+	  long double ld1, long double ld2, long double ld3)
+{
+  /* Test N1root(N2root(x)) -> pow(x,1/(N1*N2)).  */
+  /* E.g. sqrt(cbrt(x)) -> pow(x,1/6).  */
+#define ROOT_ROOT(FN1,N1,FN2,N2) \
+ extern void link_failure_##FN1##_##FN2(void); \
+ if (FN1(FN2(d1)) != pow(d1,1.0/(N1*N2)) \
+     || C99CODE (FN1##f(FN2##f(f1)) != powf(f1,1.0F/(N1*N2))) \
+     || C99CODE (FN1##l(FN2##l(ld1)) != powl(ld1,1.0L/(N1*N2)))) \
+    link_failure_##FN1##_##FN2()
+
+  ROOT_ROOT(sqrt,2,sqrt,2);
+  ROOT_ROOT(sqrt,2,cbrt,3);
+  ROOT_ROOT(cbrt,3,sqrt,2);
+  /*ROOT_ROOT(cbrt,3,cbrt,3); Intentionally not implemented.  */
+
+  /* Test pow(Nroot(x),y) -> pow(x,y/N).  */
+#define POW_ROOT(FN,N) \
+ extern void link_failure_pow_##FN(void); \
+ if (pow(FN(d1), d2) != pow(d1,d2/N) \
+     || powf(FN##f(f1),f2) != powf(f1,f2/N) \
+     || powl(FN##l(ld1),ld2) != powl(ld1,ld2/N)) \
+    link_failure_pow_##FN()
+
+  POW_ROOT(sqrt,2);
+  /*POW_ROOT(cbrt,3); Intentionally not implemented.  */
+
+  /* Test Nroot(pow(x,y)) -> pow(x,y/N).  */
+#define ROOT_POW(FN,N) \
+ extern void link_failure_##FN##_pow(void); \
+ if (FN(pow(d1, d2)) != pow(d1,d2/N) \
+     || FN##f(powf(f1,f2)) != powf(f1,f2/N) \
+     || FN##l(powl(ld1,ld2)) != powl(ld1,ld2/N)) \
+    link_failure_##FN##_pow()
+
+  ROOT_POW(sqrt,2);
+  /*ROOT_POW(cbrt,3); Intentionally not implemented.  */
+
+  /* Test pow(pow(x,y),z) -> pow(x,y*z).  */
+#define POW_POW \
+ extern void link_failure_pow_pow(void); \
+ if (pow(pow(d1, d2), d3) != pow(d1,d2*d3) \
+     || powf(powf(f1,f2),f3) != powf(f1,f2*f3) \
+     || powl(powl(ld1,ld2),ld3) != powl(ld1,ld2*ld3)) \
+    link_failure_pow_pow()
+
+  POW_POW;
+
+  /* Test Nroot(x)*Nroot(y) -> Nroot(x*y).  */
+#define ROOT_X_ROOT(FN) \
+ extern void link_failure_root_x_root(void); \
+ if (FN(d1)*FN(d2) != FN(d1*d2) \
+     || FN##f(f1)*FN##f(f2) != FN##f(f1*f2) \
+     || FN##l(ld1)*FN##l(ld2) != FN##l(ld1*ld2)) \
+    link_failure_root_x_root()
+
+  ROOT_X_ROOT(sqrt);
+  ROOT_X_ROOT(cbrt);
+  
+  /* Test pow(x,y)*pow(x,z) -> pow(x,y+z).  */
+#define POW_X_POW \
+ extern void link_failure_pow_x_pow(void); \
+ if (pow(d1,d2)*pow(d1,d3) != pow(d1,d2+d3) \
+     || powf(f1,f2)*powf(f1,f3) != powf(f1,f2+f3) \
+     || powl(ld1,ld2)*powl(ld1,ld3) != powl(ld1,ld2+ld3)) \
+    link_failure_pow_x_pow()
+
+  POW_X_POW;
+  
+}
+
+int main (void)
+{
+  return 0;
+}


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