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| author | Wilco Dijkstra <wdijkstr@arm.com> | 2017-11-16 11:54:49 +0000 |
|---|---|---|
| committer | Wilco Dijkstra <wilco@gcc.gnu.org> | 2017-11-16 11:54:49 +0000 |
| commit | 81825e283f6cec28db73af9769602b953d683e3e (patch) | |
| tree | 8126f7147441bbeb11d41053c993f7ae1046aa37 | |
| parent | efeee67f4c9fd021d2594e0271c84b7e90e63d3d (diff) | |
| download | gcc-81825e283f6cec28db73af9769602b953d683e3e.zip gcc-81825e283f6cec28db73af9769602b953d683e3e.tar.gz gcc-81825e283f6cec28db73af9769602b953d683e3e.tar.bz2 | |
Canonicalize constant multiplies in division
This patch implements some of the optimizations discussed in
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71026.
Canonicalize x / (C1 * y) into (x * C2) / y.
This moves constant multiplies out of the RHS of a division in order
to allow further simplifications (such as (C1 * x) / (C2 * y) ->
(C3 * x) / y) and to enable more reciprocal CSEs.
2017-11-16 Wilco Dijkstra <wdijkstr@arm.com>
Jackson Woodruff <jackson.woodruff@arm.com>
gcc/
PR tree-optimization/71026
* match.pd: Canonicalize constant multiplies in division.
gcc/testsuite/
PR tree-optimization/71026
* gcc.dg/cse_recip.c: New test.
Co-Authored-By: Jackson Woodruff <jackson.woodruff@arm.com>
From-SVN: r254816
| -rw-r--r-- | gcc/ChangeLog | 6 | ||||
| -rw-r--r-- | gcc/match.pd | 21 | ||||
| -rw-r--r-- | gcc/testsuite/ChangeLog | 6 | ||||
| -rw-r--r-- | gcc/testsuite/gcc.dg/cse_recip.c | 12 |
4 files changed, 34 insertions, 11 deletions
diff --git a/gcc/ChangeLog b/gcc/ChangeLog index f9a4293..aaaa638 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,4 +1,10 @@ 2017-11-16 Wilco Dijkstra <wdijkstr@arm.com> + Jackson Woodruff <jackson.woodruff@arm.com> + + PR tree-optimization/71026 + * match.pd: Canonicalize constant multiplies in division. + +2017-11-16 Wilco Dijkstra <wdijkstr@arm.com> * opts.c (default_options_table): Add OPT_fomit_frame_pointer entry. * common/config/alpha/alpha-common.c (TARGET_OPTION_OPTIMIZATION_TABLE): diff --git a/gcc/match.pd b/gcc/match.pd index 2557f08..0e21a0d 100644 --- a/gcc/match.pd +++ b/gcc/match.pd @@ -344,10 +344,18 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT) (negate @0))) (if (flag_reciprocal_math) - /* Convert (A/B)/C to A/(B*C) */ + /* Convert (A/B)/C to A/(B*C). */ (simplify (rdiv (rdiv:s @0 @1) @2) - (rdiv @0 (mult @1 @2))) + (rdiv @0 (mult @1 @2))) + + /* Canonicalize x / (C1 * y) to (x * C2) / y. */ + (simplify + (rdiv @0 (mult:s @1 REAL_CST@2)) + (with + { tree tem = const_binop (RDIV_EXPR, type, build_one_cst (type), @2); } + (if (tem) + (rdiv (mult @0 { tem; } ) @1)))) /* Convert A/(B/C) to (A/B)*C */ (simplify @@ -633,15 +641,6 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT) (if (tem) (rdiv { tem; } @1))))) -/* Convert C1/(X*C2) into (C1/C2)/X */ -(simplify - (rdiv REAL_CST@0 (mult @1 REAL_CST@2)) - (if (flag_reciprocal_math) - (with - { tree tem = const_binop (RDIV_EXPR, type, @0, @2); } - (if (tem) - (rdiv { tem; } @1))))) - /* Simplify ~X & X as zero. */ (simplify (bit_and:c (convert? @0) (convert? (bit_not @0))) diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog index 2c3e979..57bdc1c 100644 --- a/gcc/testsuite/ChangeLog +++ b/gcc/testsuite/ChangeLog @@ -1,4 +1,10 @@ 2017-11-16 Wilco Dijkstra <wdijkstr@arm.com> + Jackson Woodruff <jackson.woodruff@arm.com> + + PR tree-optimization/71026 + * gcc.dg/cse_recip.c: New test. + +2017-11-16 Wilco Dijkstra <wdijkstr@arm.com> * gcc.target/aarch64/lr_free_2.c: Fix test. * gcc.target/aarch64/spill_1.c: Likewise. diff --git a/gcc/testsuite/gcc.dg/cse_recip.c b/gcc/testsuite/gcc.dg/cse_recip.c new file mode 100644 index 0000000..88cba99 --- /dev/null +++ b/gcc/testsuite/gcc.dg/cse_recip.c @@ -0,0 +1,12 @@ +/* { dg-do compile } */ +/* { dg-options "-Ofast -fdump-tree-optimized-raw" } */ + +void +cse_recip (float x, float y, float *a) +{ + a[0] = y / (5 * x); + a[1] = y / (3 * x); + a[2] = y / x; +} + +/* { dg-final { scan-tree-dump-times "rdiv_expr" 1 "optimized" } } */ |