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re PR tree-optimization/24964 (Does not optimise abs(x)**2 to x**2)

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PR tree-optimization/24964
	* simplify-rtx.c (simplify_binary_operation_1): Add function comment.
	<MULT>: Minor clean-up.  Don't convert x*-1.0 into -x if we honor
	signaling NaNs.  Optimize -x*-x as x*x for all float modes, and
	abs(x)*abs(x) as x*x for scalar floating point modes.

	* gcc.target/i386/387-10.c: New test case.

From-SVN: r114206
This commit is contained in:
Roger Sayle 2006-05-29 16:22:05 +00:00 committed by Roger Sayle
parent 06ac89d1ca
commit 1753331b5b
4 changed files with 62 additions and 7 deletions
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8
gcc/ChangeLog
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@ -1,3 +1,11 @@
2006-05-29 Roger Sayle <roger@eyesopen.com>
PR tree-optimization/24964
* simplify-rtx.c (simplify_binary_operation_1): Add function comment.
<MULT>: Minor clean-up. Don't convert x*-1.0 into -x if we honor
signaling NaNs. Optimize -x*-x as x*x for all float modes, and
abs(x)*abs(x) as x*x for scalar floating point modes.
2006-05-29 Sebastian Pop <pop@cri.ensmp.fr>
PR middle-end/27745

36
gcc/simplify-rtx.c
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@ -1472,6 +1472,11 @@ simplify_binary_operation (enum rtx_code code, enum machine_mode mode,
return simplify_binary_operation_1 (code, mode, op0, op1, trueop0, trueop1);
}
/* Subroutine of simplify_binary_operation. Simplify a binary operation
CODE with result mode MODE, operating on OP0 and OP1. If OP0 and/or
OP1 are constant pool references, TRUEOP0 and TRUEOP1 represent the
actual constants. */
static rtx
simplify_binary_operation_1 (enum rtx_code code, enum machine_mode mode,
rtx op0, rtx op1, rtx trueop0, rtx trueop1)
@ -1907,12 +1912,12 @@ simplify_binary_operation_1 (enum rtx_code code, enum machine_mode mode,
return simplify_gen_binary (ASHIFT, mode, op0, GEN_INT (val));
/* Likewise for multipliers wider than a word. */
else if (GET_CODE (trueop1) == CONST_DOUBLE
&& (GET_MODE (trueop1) == VOIDmode
|| GET_MODE_CLASS (GET_MODE (trueop1)) == MODE_INT)
&& GET_MODE (op0) == mode
&& CONST_DOUBLE_LOW (trueop1) == 0
&& (val = exact_log2 (CONST_DOUBLE_HIGH (trueop1))) >= 0)
if (GET_CODE (trueop1) == CONST_DOUBLE
&& (GET_MODE (trueop1) == VOIDmode
|| GET_MODE_CLASS (GET_MODE (trueop1)) == MODE_INT)
&& GET_MODE (op0) == mode
&& CONST_DOUBLE_LOW (trueop1) == 0
&& (val = exact_log2 (CONST_DOUBLE_HIGH (trueop1))) >= 0)
return simplify_gen_binary (ASHIFT, mode, op0,
GEN_INT (val + HOST_BITS_PER_WIDE_INT));
@ -1927,10 +1932,27 @@ simplify_binary_operation_1 (enum rtx_code code, enum machine_mode mode,
if (REAL_VALUES_EQUAL (d, dconst2))
return simplify_gen_binary (PLUS, mode, op0, copy_rtx (op0));
if (REAL_VALUES_EQUAL (d, dconstm1))
if (!HONOR_SNANS (mode)
&& REAL_VALUES_EQUAL (d, dconstm1))
return simplify_gen_unary (NEG, mode, op0, mode);
}
/* Optimize -x * -x as x * x. */
if (FLOAT_MODE_P (mode)
&& GET_CODE (op0) == NEG
&& GET_CODE (op1) == NEG
&& rtx_equal_p (XEXP (op0, 0), XEXP (op1, 0))
&& !side_effects_p (XEXP (op0, 0)))
return simplify_gen_binary (MULT, mode, XEXP (op0, 0), XEXP (op1, 0));
/* Likewise, optimize abs(x) * abs(x) as x * x. */
if (SCALAR_FLOAT_MODE_P (mode)
&& GET_CODE (op0) == ABS
&& GET_CODE (op1) == ABS
&& rtx_equal_p (XEXP (op0, 0), XEXP (op1, 0))
&& !side_effects_p (XEXP (op0, 0)))
return simplify_gen_binary (MULT, mode, XEXP (op0, 0), XEXP (op1, 0));
/* Reassociate multiplication, but for floating point MULTs
only when the user specifies unsafe math optimizations. */
if (! FLOAT_MODE_P (mode)

5
gcc/testsuite/ChangeLog
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@ -1,3 +1,8 @@
2006-05-29 Roger Sayle <roger@eyesopen.com>
PR tree-optimization/24964
* gcc.target/i386/387-10.c: New test case.
2006-05-28 Thomas Koenig <Thomas.Koenig@online.de>
* intrinsics/string_intrinsics.c (compare_string):

20
gcc/testsuite/gcc.target/i386/387-10.c Normal file
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@ -0,0 +1,20 @@
/* PR tree-optimization/24964 */
/* { dg-do compile { target i?86-*-* x86_64-*-* } } */
/* { dg-options "-O2 -mfpmath=387" } */
double fabs(double x);
double test1(double x)
{
double t = fabs(x);
return t*t;
}
double test2(double x)
{
double t = -x;
return t*t;
}
/* { dg-final { scan-assembler-not "fchs" } } */
/* { dg-final { scan-assembler-not "fabs" } } */