Message ID | 20220524225156.4026293-1-philipp.tomsich@vrull.eu |
---|---|
State | New |
Headers | show |
Series | [v1,1/3] RISC-V: Split "(a & (1 << BIT_NO)) ? 0 : -1" to bexti + addi | expand |
Kito, Looks like this series fell by the wayside (possibly, because it didn't have a cover-letter and was easier to miss)? Thanks, Philipp. On Wed, 25 May 2022 at 00:52, Philipp Tomsich <philipp.tomsich@vrull.eu> wrote: > > Consider creating a polarity-reversed mask from a set-bit (i.e., if > the bit is set, produce all-ones; otherwise: all-zeros). Using Zbb, > this can be expressed as bexti, followed by an addi of minus-one. To > enable the combiner to discover this opportunity, we need to split the > canonical expression for "(a & (1 << BIT_NO)) ? 0 : -1" into a form > combinable into bexti. > > Consider the function: > long f(long a) > { > return (a & (1 << BIT_NO)) ? 0 : -1; > } > This produces the following sequence prior to this change: > andi a0,a0,16 > seqz a0,a0 > neg a0,a0 > ret > Following this change, it results in: > bexti a0,a0,4 > addi a0,a0,-1 > ret > > Signed-off-by: Philipp Tomsich <philipp.tomsich@vrull.eu> > > gcc/ChangeLog: > > * config/riscv/bitmanip.md: Add a splitter to generate > polarity-reversed masks from a set bit using bexti + addi. > > gcc/testsuite/ChangeLog: > > * gcc.target/riscv/zbs-bexti.c: New test. > > --- > > gcc/config/riscv/bitmanip.md | 13 +++++++++++++ > gcc/testsuite/gcc.target/riscv/zbs-bexti.c | 14 ++++++++++++++ > 2 files changed, 27 insertions(+) > create mode 100644 gcc/testsuite/gcc.target/riscv/zbs-bexti.c > > diff --git a/gcc/config/riscv/bitmanip.md b/gcc/config/riscv/bitmanip.md > index 0ab9ffe3c0b..ea5dea13cfb 100644 > --- a/gcc/config/riscv/bitmanip.md > +++ b/gcc/config/riscv/bitmanip.md > @@ -340,3 +340,16 @@ (define_insn "*bexti" > "TARGET_ZBS" > "bexti\t%0,%1,%2" > [(set_attr "type" "bitmanip")]) > + > +;; We can create a polarity-reversed mask (i.e. bit N -> { set = 0, clear = -1 }) > +;; using a bext(i) followed by an addi instruction. > +;; This splits the canonical representation of "(a & (1 << BIT_NO)) ? 0 : -1". > +(define_split > + [(set (match_operand:GPR 0 "register_operand") > + (neg:GPR (eq:GPR (zero_extract:GPR (match_operand:GPR 1 "register_operand") > + (const_int 1) > + (match_operand 2)) > + (const_int 0))))] > + "TARGET_ZBS" > + [(set (match_dup 0) (zero_extract:GPR (match_dup 1) (const_int 1) (match_dup 2))) > + (set (match_dup 0) (plus:GPR (match_dup 0) (const_int -1)))]) > diff --git a/gcc/testsuite/gcc.target/riscv/zbs-bexti.c b/gcc/testsuite/gcc.target/riscv/zbs-bexti.c > new file mode 100644 > index 00000000000..99e3b58309c > --- /dev/null > +++ b/gcc/testsuite/gcc.target/riscv/zbs-bexti.c > @@ -0,0 +1,14 @@ > +/* { dg-do compile } */ > +/* { dg-options "-march=rv64gc_zbs -mabi=lp64 -O2" } */ > + > +/* bexti */ > +#define BIT_NO 4 > + > +long > +foo0 (long a) > +{ > + return (a & (1 << BIT_NO)) ? 0 : -1; > +} > + > +/* { dg-final { scan-assembler "bexti" } } */ > +/* { dg-final { scan-assembler "addi" } } */ > -- > 2.34.1 >
Hi Philipp: This patch series is LGTM, but plz introduce new pseudo when can_create_pseudo_p like what we discussed in https://gcc.gnu.org/pipermail/gcc-patches/2022-June/596305.html, you can commit with the change with a [committed] patch mail :) On Thu, Jun 16, 2022 at 5:32 PM Philipp Tomsich <philipp.tomsich@vrull.eu> wrote: > > Kito, > > Looks like this series fell by the wayside (possibly, because it > didn't have a cover-letter and was easier to miss)? > > Thanks, > Philipp. > > On Wed, 25 May 2022 at 00:52, Philipp Tomsich <philipp.tomsich@vrull.eu> wrote: > > > > Consider creating a polarity-reversed mask from a set-bit (i.e., if > > the bit is set, produce all-ones; otherwise: all-zeros). Using Zbb, > > this can be expressed as bexti, followed by an addi of minus-one. To > > enable the combiner to discover this opportunity, we need to split the > > canonical expression for "(a & (1 << BIT_NO)) ? 0 : -1" into a form > > combinable into bexti. > > > > Consider the function: > > long f(long a) > > { > > return (a & (1 << BIT_NO)) ? 0 : -1; > > } > > This produces the following sequence prior to this change: > > andi a0,a0,16 > > seqz a0,a0 > > neg a0,a0 > > ret > > Following this change, it results in: > > bexti a0,a0,4 > > addi a0,a0,-1 > > ret > > > > Signed-off-by: Philipp Tomsich <philipp.tomsich@vrull.eu> > > > > gcc/ChangeLog: > > > > * config/riscv/bitmanip.md: Add a splitter to generate > > polarity-reversed masks from a set bit using bexti + addi. > > > > gcc/testsuite/ChangeLog: > > > > * gcc.target/riscv/zbs-bexti.c: New test. > > > > --- > > > > gcc/config/riscv/bitmanip.md | 13 +++++++++++++ > > gcc/testsuite/gcc.target/riscv/zbs-bexti.c | 14 ++++++++++++++ > > 2 files changed, 27 insertions(+) > > create mode 100644 gcc/testsuite/gcc.target/riscv/zbs-bexti.c > > > > diff --git a/gcc/config/riscv/bitmanip.md b/gcc/config/riscv/bitmanip.md > > index 0ab9ffe3c0b..ea5dea13cfb 100644 > > --- a/gcc/config/riscv/bitmanip.md > > +++ b/gcc/config/riscv/bitmanip.md > > @@ -340,3 +340,16 @@ (define_insn "*bexti" > > "TARGET_ZBS" > > "bexti\t%0,%1,%2" > > [(set_attr "type" "bitmanip")]) > > + > > +;; We can create a polarity-reversed mask (i.e. bit N -> { set = 0, clear = -1 }) > > +;; using a bext(i) followed by an addi instruction. > > +;; This splits the canonical representation of "(a & (1 << BIT_NO)) ? 0 : -1". > > +(define_split > > + [(set (match_operand:GPR 0 "register_operand") > > + (neg:GPR (eq:GPR (zero_extract:GPR (match_operand:GPR 1 "register_operand") > > + (const_int 1) > > + (match_operand 2)) > > + (const_int 0))))] > > + "TARGET_ZBS" > > + [(set (match_dup 0) (zero_extract:GPR (match_dup 1) (const_int 1) (match_dup 2))) > > + (set (match_dup 0) (plus:GPR (match_dup 0) (const_int -1)))]) > > diff --git a/gcc/testsuite/gcc.target/riscv/zbs-bexti.c b/gcc/testsuite/gcc.target/riscv/zbs-bexti.c > > new file mode 100644 > > index 00000000000..99e3b58309c > > --- /dev/null > > +++ b/gcc/testsuite/gcc.target/riscv/zbs-bexti.c > > @@ -0,0 +1,14 @@ > > +/* { dg-do compile } */ > > +/* { dg-options "-march=rv64gc_zbs -mabi=lp64 -O2" } */ > > + > > +/* bexti */ > > +#define BIT_NO 4 > > + > > +long > > +foo0 (long a) > > +{ > > + return (a & (1 << BIT_NO)) ? 0 : -1; > > +} > > + > > +/* { dg-final { scan-assembler "bexti" } } */ > > +/* { dg-final { scan-assembler "addi" } } */ > > -- > > 2.34.1 > >
diff --git a/gcc/config/riscv/bitmanip.md b/gcc/config/riscv/bitmanip.md index 0ab9ffe3c0b..ea5dea13cfb 100644 --- a/gcc/config/riscv/bitmanip.md +++ b/gcc/config/riscv/bitmanip.md @@ -340,3 +340,16 @@ (define_insn "*bexti" "TARGET_ZBS" "bexti\t%0,%1,%2" [(set_attr "type" "bitmanip")]) + +;; We can create a polarity-reversed mask (i.e. bit N -> { set = 0, clear = -1 }) +;; using a bext(i) followed by an addi instruction. +;; This splits the canonical representation of "(a & (1 << BIT_NO)) ? 0 : -1". +(define_split + [(set (match_operand:GPR 0 "register_operand") + (neg:GPR (eq:GPR (zero_extract:GPR (match_operand:GPR 1 "register_operand") + (const_int 1) + (match_operand 2)) + (const_int 0))))] + "TARGET_ZBS" + [(set (match_dup 0) (zero_extract:GPR (match_dup 1) (const_int 1) (match_dup 2))) + (set (match_dup 0) (plus:GPR (match_dup 0) (const_int -1)))]) diff --git a/gcc/testsuite/gcc.target/riscv/zbs-bexti.c b/gcc/testsuite/gcc.target/riscv/zbs-bexti.c new file mode 100644 index 00000000000..99e3b58309c --- /dev/null +++ b/gcc/testsuite/gcc.target/riscv/zbs-bexti.c @@ -0,0 +1,14 @@ +/* { dg-do compile } */ +/* { dg-options "-march=rv64gc_zbs -mabi=lp64 -O2" } */ + +/* bexti */ +#define BIT_NO 4 + +long +foo0 (long a) +{ + return (a & (1 << BIT_NO)) ? 0 : -1; +} + +/* { dg-final { scan-assembler "bexti" } } */ +/* { dg-final { scan-assembler "addi" } } */
Consider creating a polarity-reversed mask from a set-bit (i.e., if the bit is set, produce all-ones; otherwise: all-zeros). Using Zbb, this can be expressed as bexti, followed by an addi of minus-one. To enable the combiner to discover this opportunity, we need to split the canonical expression for "(a & (1 << BIT_NO)) ? 0 : -1" into a form combinable into bexti. Consider the function: long f(long a) { return (a & (1 << BIT_NO)) ? 0 : -1; } This produces the following sequence prior to this change: andi a0,a0,16 seqz a0,a0 neg a0,a0 ret Following this change, it results in: bexti a0,a0,4 addi a0,a0,-1 ret Signed-off-by: Philipp Tomsich <philipp.tomsich@vrull.eu> gcc/ChangeLog: * config/riscv/bitmanip.md: Add a splitter to generate polarity-reversed masks from a set bit using bexti + addi. gcc/testsuite/ChangeLog: * gcc.target/riscv/zbs-bexti.c: New test. --- gcc/config/riscv/bitmanip.md | 13 +++++++++++++ gcc/testsuite/gcc.target/riscv/zbs-bexti.c | 14 ++++++++++++++ 2 files changed, 27 insertions(+) create mode 100644 gcc/testsuite/gcc.target/riscv/zbs-bexti.c