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| author | Richard Henderson <rth@cygnus.com> | 1999-08-24 15:37:34 -0700 |
|---|---|---|
| committer | Richard Henderson <rth@gcc.gnu.org> | 1999-08-24 15:37:34 -0700 |
| commit | abe4f192b718200fec889f10b289503e22a3df06 (patch) | |
| tree | ba72a7fe3c6c5380b0f55be08ce8de1aaba58b59 | |
| parent | f2a1bc02679df06d8461df03f48ebaafe5e4307e (diff) | |
| download | gcc-abe4f192b718200fec889f10b289503e22a3df06.zip gcc-abe4f192b718200fec889f10b289503e22a3df06.tar.gz gcc-abe4f192b718200fec889f10b289503e22a3df06.tar.bz2 | |
fold-const.c (fold): Reassociate (+ (+ (* a b) c) (* d e)) as (+ (+ (* a b) (* d e)) c).
* fold-const.c (fold): Reassociate (+ (+ (* a b) c) (* d e))
as (+ (+ (* a b) (* d e)) c). Factor a common power-of-two
multiplicand out of (+ (* a b) (* c d)).
From-SVN: r28829
| -rw-r--r-- | gcc/ChangeLog | 6 | ||||
| -rw-r--r-- | gcc/fold-const.c | 61 |
2 files changed, 67 insertions, 0 deletions
diff --git a/gcc/ChangeLog b/gcc/ChangeLog index e98401a..b6817cf 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,9 @@ +Tue Aug 24 15:37:03 1999 Richard Henderson <rth@cygnus.com> + + * fold-const.c (fold): Reassociate (+ (+ (* a b) c) (* d e)) + as (+ (+ (* a b) (* d e)) c). Factor a common power-of-two + multiplicand out of (+ (* a b) (* c d)). + Tue Aug 24 11:46:10 1999 Bob Manson <manson@cygnus.com> Richard Henderson <rth@cygnus.com> diff --git a/gcc/fold-const.c b/gcc/fold-const.c index dc9ca93..327ebd3 100644 --- a/gcc/fold-const.c +++ b/gcc/fold-const.c @@ -4757,6 +4757,37 @@ fold (expr) goto bit_ior; } + /* Reassociate (plus (plus (mult) (foo)) (mult)) as + (plus (plus (mult) (mult)) (foo)) so that we can + take advantage of the factoring cases below. */ + if ((TREE_CODE (arg0) == PLUS_EXPR + && TREE_CODE (arg1) == MULT_EXPR) + || (TREE_CODE (arg1) == PLUS_EXPR + && TREE_CODE (arg0) == MULT_EXPR)) + { + tree parg0, parg1, parg, marg; + + if (TREE_CODE (arg0) == PLUS_EXPR) + parg = arg0, marg = arg1; + else + parg = arg1, marg = arg0; + parg0 = TREE_OPERAND (parg, 0); + parg1 = TREE_OPERAND (parg, 1); + STRIP_NOPS (parg0); + STRIP_NOPS (parg1); + + if (TREE_CODE (parg0) == MULT_EXPR + && TREE_CODE (parg1) != MULT_EXPR) + return fold (build (PLUS_EXPR, type, + fold (build (PLUS_EXPR, type, parg0, marg)), + parg1)); + if (TREE_CODE (parg0) != MULT_EXPR + && TREE_CODE (parg1) == MULT_EXPR) + return fold (build (PLUS_EXPR, type, + fold (build (PLUS_EXPR, type, parg1, marg)), + parg0)); + } + if (TREE_CODE (arg0) == MULT_EXPR && TREE_CODE (arg1) == MULT_EXPR) { tree arg00, arg01, arg10, arg11; @@ -4782,6 +4813,36 @@ fold (expr) else if (operand_equal_p (arg01, arg10, 0)) same = arg01, alt0 = arg00, alt1 = arg11; + /* No identical multiplicands; see if we can find a common + power-of-two factor in non-power-of-two multiplies. This + can help in multi-dimensional array access. */ + else if (TREE_CODE (arg01) == INTEGER_CST + && TREE_CODE (arg11) == INTEGER_CST + && TREE_INT_CST_HIGH (arg01) == 0 + && TREE_INT_CST_HIGH (arg11) == 0) + { + HOST_WIDE_INT int01, int11, tmp; + int01 = TREE_INT_CST_LOW (arg01); + int11 = TREE_INT_CST_LOW (arg11); + + /* Move min of absolute values to int11. */ + if ((int01 >= 0 ? int01 : -int01) + < (int11 >= 0 ? int11 : -int11)) + { + tmp = int01, int01 = int11, int11 = tmp; + alt0 = arg00, arg00 = arg10, arg10 = alt0; + alt0 = arg01, arg01 = arg11, arg11 = alt0; + } + + if (exact_log2 (int11) > 0 && int01 % int11 == 0) + { + alt0 = fold (build (MULT_EXPR, type, arg00, + build_int_2 (int01 / int11, 0))); + alt1 = arg10; + same = arg11; + } + } + if (same) return fold (build (MULT_EXPR, type, fold (build (PLUS_EXPR, type, alt0, alt1)), |