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combine.c (num_sign_bit_copies): In NEG...

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* combine.c (num_sign_bit_copies): In NEG, MULT, DIV and MOD cases,
        when a test can't be performed due to limited width of
        HOST_BITS_PER_WIDE_INT, use the more conservative approximation.
        Fix UDIV case for cases where the first operand has the highest bit
        set.

From-SVN: r24547
This commit is contained in:
Bernd Schmidt 1999-01-06 16:33:29 -07:00 • committed by Jeff Law
parent 548e44b336
commit 70186b342c
2 changed files with 36 additions and 18 deletions
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8
gcc/ChangeLog
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@ -1,3 +1,11 @@
Thu Jan 7 00:29:25 199 Bernd Schmidt <crux@pool.informatik.rwth-aachen.de>
* combine.c (num_sign_bit_copies): In NEG, MULT, DIV and MOD cases,
when a test can't be performed due to limited width of
HOST_BITS_PER_WIDE_INT, use the more conservative approximation.
Fix UDIV case for cases where the first operand has the highest bit
set.
Thu Jan 7 00:01:38 1999 Lutz Vieweg <lkv@mania.robin.de>
* pa.h (reg_class): Add FPUPPER_REGS.

46
gcc/combine.c
View file

@ -8020,13 +8020,15 @@ num_sign_bit_copies (x, mode)
is known to be positive, the number of sign bit copies is the
same as that of the input. Finally, if the input has just one bit
that might be nonzero, all the bits are copies of the sign bit. */
num0 = num_sign_bit_copies (XEXP (x, 0), mode);
if (bitwidth > HOST_BITS_PER_WIDE_INT)
return num0 > 1 ? num0 - 1 : 1;
nonzero = nonzero_bits (XEXP (x, 0), mode);
if (nonzero == 1)
return bitwidth;
num0 = num_sign_bit_copies (XEXP (x, 0), mode);
if (num0 > 1
&& bitwidth <= HOST_BITS_PER_WIDE_INT
&& (((HOST_WIDE_INT) 1 << (bitwidth - 1)) & nonzero))
num0--;
@ -8070,19 +8072,27 @@ num_sign_bit_copies (x, mode)
result = bitwidth - (bitwidth - num0) - (bitwidth - num1);
if (result > 0
&& bitwidth <= HOST_BITS_PER_WIDE_INT
&& ((nonzero_bits (XEXP (x, 0), mode)
& ((HOST_WIDE_INT) 1 << (bitwidth - 1))) != 0)
&& ((nonzero_bits (XEXP (x, 1), mode)
& ((HOST_WIDE_INT) 1 << (bitwidth - 1))) != 0))
&& (bitwidth > HOST_BITS_PER_WIDE_INT
|| (((nonzero_bits (XEXP (x, 0), mode)
& ((HOST_WIDE_INT) 1 << (bitwidth - 1))) != 0)
&& ((nonzero_bits (XEXP (x, 1), mode)
& ((HOST_WIDE_INT) 1 << (bitwidth - 1))) != 0))))
result--;
return MAX (1, result);
case UDIV:
/* The result must be <= the first operand. */
return num_sign_bit_copies (XEXP (x, 0), mode);
/* The result must be <= the first operand. If the first operand
has the high bit set, we know nothing about the number of sign
bit copies. */
if (bitwidth > HOST_BITS_PER_WIDE_INT)
return 1;
else if ((nonzero_bits (XEXP (x, 0), mode)
& ((HOST_WIDE_INT) 1 << (bitwidth - 1))) != 0)
return 1;
else
return num_sign_bit_copies (XEXP (x, 0), mode);
case UMOD:
/* The result must be <= the scond operand. */
return num_sign_bit_copies (XEXP (x, 1), mode);
@ -8093,20 +8103,20 @@ num_sign_bit_copies (x, mode)
to add 1. */
result = num_sign_bit_copies (XEXP (x, 0), mode);
if (result > 1
&& bitwidth <= HOST_BITS_PER_WIDE_INT
&& (nonzero_bits (XEXP (x, 1), mode)
& ((HOST_WIDE_INT) 1 << (bitwidth - 1))) != 0)
result --;
&& (bitwidth > HOST_BITS_PER_WIDE_INT
|| (nonzero_bits (XEXP (x, 1), mode)
& ((HOST_WIDE_INT) 1 << (bitwidth - 1))) != 0))
result--;
return result;
case MOD:
result = num_sign_bit_copies (XEXP (x, 1), mode);
if (result > 1
&& bitwidth <= HOST_BITS_PER_WIDE_INT
&& (nonzero_bits (XEXP (x, 1), mode)
& ((HOST_WIDE_INT) 1 << (bitwidth - 1))) != 0)
result --;
&& (bitwidth > HOST_BITS_PER_WIDE_INT
|| (nonzero_bits (XEXP (x, 1), mode)
& ((HOST_WIDE_INT) 1 << (bitwidth - 1))) != 0))
result--;
return result;