| Message ID | 20210114090938.GV1034503@tucnak |
|---|---|
| State | New |
| Headers | show |
| Series | match.pd: Optimize ~(X >> Y) to ~X >> Y if ~X can be simplified [PR96688] | expand |
On Thu, 14 Jan 2021, Jakub Jelinek wrote: > Hi! > > This patch optimizes two GIMPLE operations into just one. > As mentioned in the PR, there is some risk this might create more expensive > constants, but sometimes it will make them on the other side less expensive, > it really depends on the exact value. > And if it is an important issue, we should do it in md or during expansion. > > Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk? OK. Thanks, Richard. > 2021-01-13 Jakub Jelinek <jakub@redhat.com> > > PR tree-optimization/96688 > * match.pd (~(X >> Y) -> ~X >> Y): New simplification if > ~X can be simplified. > > * gcc.dg/tree-ssa/pr96688.c: New test. > * gcc.dg/tree-ssa/reassoc-37.c: Adjust scan-tree-dump regex. > * gcc.target/i386/pr66821.c: Likewise. > > --- gcc/match.pd.jj 2021-01-13 15:27:13.843788907 +0100 > +++ gcc/match.pd 2021-01-13 18:01:09.706568135 +0100 > @@ -1109,6 +1109,18 @@ (define_operator_list COND_TERNARY > && wi::to_wide (@1) != wi::min_value (TYPE_PRECISION (type), > SIGNED)) > (minus (plus @1 { build_minus_one_cst (type); }) @0)))) > + > +/* ~(X >> Y) -> ~X >> Y if ~X can be simplified. */ > +(simplify > + (bit_not (rshift:s @0 @1)) > + (if (!TYPE_UNSIGNED (TREE_TYPE (@0))) > + (rshift (bit_not! @0) @1) > + /* For logical right shifts, this is possible only if @0 doesn't > + have MSB set and the logical right shift is changed into > + arithmetic shift. */ > + (if (!wi::neg_p (tree_nonzero_bits (@0))) > + (with { tree stype = signed_type_for (TREE_TYPE (@0)); } > + (convert (rshift (bit_not! (convert:stype @0)) @1)))))) > #endif > > /* x + (x & 1) -> (x + 1) & ~1 */ > --- gcc/testsuite/gcc.dg/tree-ssa/pr96688.c.jj 2021-01-13 19:12:26.396363212 +0100 > +++ gcc/testsuite/gcc.dg/tree-ssa/pr96688.c 2021-01-13 19:13:32.146628538 +0100 > @@ -0,0 +1,24 @@ > +/* PR tree-optimization/96688 */ > +/* { dg-do compile } */ > +/* { dg-options "-O2 -fdump-tree-optimized" } */ > +/* { dg-final { scan-tree-dump-times " = -124 >> " 2 "optimized" } } */ > +/* { dg-final { scan-tree-dump-times " >> " 3 "optimized" } } */ > +/* { dg-final { scan-tree-dump-times " = ~" 1 "optimized" } } */ > + > +int > +foo (int x) > +{ > + return ~(123 >> x); > +} > + > +unsigned > +bar (int x) > +{ > + return ~(123U >> x); > +} > + > +unsigned > +baz (int x) > +{ > + return ~(~123U >> x); > +} > --- gcc/testsuite/gcc.dg/tree-ssa/reassoc-37.c.jj 2020-01-12 11:54:37.609395365 +0100 > +++ gcc/testsuite/gcc.dg/tree-ssa/reassoc-37.c 2021-01-14 10:04:03.100243196 +0100 > @@ -12,5 +12,5 @@ foo (int x) > } > > /* Check if the tests have been folded into a bit test. */ > -/* { dg-final { scan-tree-dump "(8784908|0x0*860c0c)" "optimized" { target i?86-*-* x86_64-*-* } } } */ > +/* { dg-final { scan-tree-dump "(8784908|-8784909|0x0*860c0c)" "optimized" { target i?86-*-* x86_64-*-* } } } */ > /* { dg-final { scan-tree-dump "(<<|>>)" "optimized" { target i?86-*-* x86_64-*-* } } } */ > --- gcc/testsuite/gcc.target/i386/pr66821.c.jj 2020-01-12 11:54:37.969389933 +0100 > +++ gcc/testsuite/gcc.target/i386/pr66821.c 2021-01-14 10:04:41.210807013 +0100 > @@ -11,5 +11,5 @@ foo (int x) > } > > /* Check if the tests have been folded into a bit test. */ > -/* { dg-final { scan-tree-dump "(8784908|0x0*860c0c)" "optimized" } } */ > +/* { dg-final { scan-tree-dump "(8784908|-8784909|0x0*860c0c)" "optimized" } } */ > /* { dg-final { scan-tree-dump "(<<|>>)" "optimized" } } */ > > Jakub > >
--- gcc/match.pd.jj 2021-01-13 15:27:13.843788907 +0100 +++ gcc/match.pd 2021-01-13 18:01:09.706568135 +0100 @@ -1109,6 +1109,18 @@ (define_operator_list COND_TERNARY && wi::to_wide (@1) != wi::min_value (TYPE_PRECISION (type), SIGNED)) (minus (plus @1 { build_minus_one_cst (type); }) @0)))) + +/* ~(X >> Y) -> ~X >> Y if ~X can be simplified. */ +(simplify + (bit_not (rshift:s @0 @1)) + (if (!TYPE_UNSIGNED (TREE_TYPE (@0))) + (rshift (bit_not! @0) @1) + /* For logical right shifts, this is possible only if @0 doesn't + have MSB set and the logical right shift is changed into + arithmetic shift. */ + (if (!wi::neg_p (tree_nonzero_bits (@0))) + (with { tree stype = signed_type_for (TREE_TYPE (@0)); } + (convert (rshift (bit_not! (convert:stype @0)) @1)))))) #endif /* x + (x & 1) -> (x + 1) & ~1 */ --- gcc/testsuite/gcc.dg/tree-ssa/pr96688.c.jj 2021-01-13 19:12:26.396363212 +0100 +++ gcc/testsuite/gcc.dg/tree-ssa/pr96688.c 2021-01-13 19:13:32.146628538 +0100 @@ -0,0 +1,24 @@ +/* PR tree-optimization/96688 */ +/* { dg-do compile } */ +/* { dg-options "-O2 -fdump-tree-optimized" } */ +/* { dg-final { scan-tree-dump-times " = -124 >> " 2 "optimized" } } */ +/* { dg-final { scan-tree-dump-times " >> " 3 "optimized" } } */ +/* { dg-final { scan-tree-dump-times " = ~" 1 "optimized" } } */ + +int +foo (int x) +{ + return ~(123 >> x); +} + +unsigned +bar (int x) +{ + return ~(123U >> x); +} + +unsigned +baz (int x) +{ + return ~(~123U >> x); +} --- gcc/testsuite/gcc.dg/tree-ssa/reassoc-37.c.jj 2020-01-12 11:54:37.609395365 +0100 +++ gcc/testsuite/gcc.dg/tree-ssa/reassoc-37.c 2021-01-14 10:04:03.100243196 +0100 @@ -12,5 +12,5 @@ foo (int x) } /* Check if the tests have been folded into a bit test. */ -/* { dg-final { scan-tree-dump "(8784908|0x0*860c0c)" "optimized" { target i?86-*-* x86_64-*-* } } } */ +/* { dg-final { scan-tree-dump "(8784908|-8784909|0x0*860c0c)" "optimized" { target i?86-*-* x86_64-*-* } } } */ /* { dg-final { scan-tree-dump "(<<|>>)" "optimized" { target i?86-*-* x86_64-*-* } } } */ --- gcc/testsuite/gcc.target/i386/pr66821.c.jj 2020-01-12 11:54:37.969389933 +0100 +++ gcc/testsuite/gcc.target/i386/pr66821.c 2021-01-14 10:04:41.210807013 +0100 @@ -11,5 +11,5 @@ foo (int x) } /* Check if the tests have been folded into a bit test. */ -/* { dg-final { scan-tree-dump "(8784908|0x0*860c0c)" "optimized" } } */ +/* { dg-final { scan-tree-dump "(8784908|-8784909|0x0*860c0c)" "optimized" } } */ /* { dg-final { scan-tree-dump "(<<|>>)" "optimized" } } */