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| author | Roger Sayle <roger@eyesopen.com> | 2004-07-11 21:56:37 +0000 |
|---|---|---|
| committer | Roger Sayle <sayle@gcc.gnu.org> | 2004-07-11 21:56:37 +0000 |
| commit | df23e6bbfaa8254963aa5254a851c942f3c8b594 (patch) | |
| tree | acc595c4c6c4e009a369389090739103f3b7a6c8 /gcc | |
| parent | abd1b60de7c2ce3fc9a2d8b56c28df7639e3735a (diff) | |
| download | gcc-df23e6bbfaa8254963aa5254a851c942f3c8b594.zip gcc-df23e6bbfaa8254963aa5254a851c942f3c8b594.tar.gz gcc-df23e6bbfaa8254963aa5254a851c942f3c8b594.tar.bz2 | |
fold-const.c (fold): Canonicalize X + -C as X - C for floating point additions...
* fold-const.c (fold) <PLUS_EXPR>: Canonicalize X + -C as X - C for
floating point additions, to keep real immediate constant positive.
<MINUS_EXPR>: For floating point subtractions, only transform X - -C
into X + C, and leave positive real constants as X - C.
From-SVN: r84535
Diffstat (limited to 'gcc')
| -rw-r--r-- | gcc/ChangeLog | 7 | ||||
| -rw-r--r-- | gcc/fold-const.c | 16 |
2 files changed, 22 insertions, 1 deletions
diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 77123a0..89ff347 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,10 @@ +2004-07-11 Roger Sayle <roger@eyesopen.com> + + * fold-const.c (fold) <PLUS_EXPR>: Canonicalize X + -C as X - C for + floating point additions, to keep real immediate constant positive. + <MINUS_EXPR>: For floating point subtractions, only transform X - -C + into X + C, and leave positive real constants as X - C. + 2004-07-11 John David Anglin <dave.anglin@nrc-cnrc.gc.ca> * pa.c (hppa_gimplify_va_arg_expr): Remove comment. diff --git a/gcc/fold-const.c b/gcc/fold-const.c index f1927f2..bc1e877 100644 --- a/gcc/fold-const.c +++ b/gcc/fold-const.c @@ -6589,6 +6589,17 @@ fold (tree expr) if (fold_real_zero_addition_p (TREE_TYPE (arg1), arg0, 0)) return non_lvalue (fold_convert (type, arg1)); + /* Convert X + -C into X - C. */ + if (TREE_CODE (arg1) == REAL_CST + && REAL_VALUE_NEGATIVE (TREE_REAL_CST (arg1))) + { + tem = fold_negate_const (arg1, type); + if (!TREE_OVERFLOW (arg1) || !flag_trapping_math) + return fold (build2 (MINUS_EXPR, type, + fold_convert (type, arg0), + fold_convert (type, tem))); + } + /* Convert x+x into x*2.0. */ if (operand_equal_p (arg0, arg1, 0) && SCALAR_FLOAT_TYPE_P (type)) @@ -6921,7 +6932,10 @@ fold (tree expr) /* A - B -> A + (-B) if B is easily negatable. */ if (!wins && negate_expr_p (arg1) - && (FLOAT_TYPE_P (type) + && ((FLOAT_TYPE_P (type) + /* Avoid this transformation if B is a positive REAL_CST. */ + && (TREE_CODE (arg1) != REAL_CST + || REAL_VALUE_NEGATIVE (TREE_REAL_CST (arg1)))) || (INTEGRAL_TYPE_P (type) && flag_wrapv && !flag_trapv))) return fold (build2 (PLUS_EXPR, type, arg0, negate_expr (arg1))); |