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ChangeLog formatting and test case fixed. On 09/30/2015 12:30 PM, Marc Glisse wrote:
On Fri, 18 Sep 2015, Marc Glisse wrote:+(bit_and:c (op @0 @1) (op @0 @2)):c seems useless here. On the other hand, it might make sense to use op:s since this is mostly useful if it removes the 2 original comparisons.As I was saying, :c is useless. (x:c y z) is replaced by two copies of the transformation, one with (x y z) and the other with (x z y) In your transformation, both versions would be equivalent, so the second one is redundant. Also, if you have: a=x<y; b=x<z; c=a&b; reuse(a); reuse(b); (i.e. the comparison results are used for more than just this bit_and) then your transformation may make the code more expensive. To avoid this, you can write op:s, meaning that the result of op is used only once.
-- Michael Collison Linaro Toolchain Working Group michael.collison@linaro.org
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diff --git a/gcc/match.pd b/gcc/match.pd index bd5c267..ef2e025 100644 --- a/gcc/match.pd +++ b/gcc/match.pd @@ -2311,3 +2311,13 @@ along with GCC; see the file COPYING3. If not see (with { tree utype = unsigned_type_for (TREE_TYPE (@0)); } (convert (bit_and (op (convert:utype @0) (convert:utype @1)) (convert:utype @4)))))))) + +/* Transform (@0 < @1 and @0 < @2) to use min, + (@0 > @1 and @0 > @2) to use max */ +(for op (lt le gt ge) + ext (min min max max) +(simplify +(bit_and (op:s @0 @1) (op:s @0 @2)) +(if (INTEGRAL_TYPE_P (TREE_TYPE (@0))) +(op @0 (ext @1 @2))))) + diff --git a/gcc/testsuite/gcc.dg/tree-ssa/minmax-loopend.c b/gcc/testsuite/gcc.dg/tree-ssa/minmax-loopend.c new file mode 100644 index 0000000..2e4300c --- /dev/null +++ b/gcc/testsuite/gcc.dg/tree-ssa/minmax-loopend.c @@ -0,0 +1,17 @@ +/* { dg-do compile } */ +/* { dg-options "-O2 -fdump-tree-optimized" } */ + +int min_test(long a, long b, long c) { + int cmp1 = a < b; + int cmp2 = a < c; + return cmp1 & cmp2; +} + +int max_test (long a, long b, long c) { + int cmp1 = a > b; + int cmp2 = a > c; + return cmp1 & cmp2; +} + +/* { dg-final { scan-tree-dump-times "MIN_EXPR" 1 "optimized" } } */ +/* { dg-final { scan-tree-dump-times "MAX_EXPR" 1 "optimized" } } */ -- 1.9.1
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