[PATCH] RISC-V: Add split pattern to generate SFB instructions. [PR113095]

[PATCH] RISC-V: Add split pattern to generate SFB instructions. [PR113095]

[Monk Chiang]

Since the match.pd transforms (zero_one == 0) ? y : z <op> y,
into ((typeof(y))zero_one * z) <op> y. Add splitters to recongize
this expression to generate SFB instructions.

gcc/ChangeLog:
	PR target/113095
	* config/riscv/sfb.md: New splitters to rewrite single bit
	sign extension as the condition to SFB instructions.

gcc/testsuite/ChangeLog:
        * gcc.target/riscv/sfb.c: New test.
---
 gcc/config/riscv/sfb.md              | 32 ++++++++++++++++++++++++++++
 gcc/testsuite/gcc.target/riscv/sfb.c | 24 +++++++++++++++++++++
 2 files changed, 56 insertions(+)
 create mode 100644 gcc/testsuite/gcc.target/riscv/sfb.c

diff --git a/gcc/config/riscv/sfb.md b/gcc/config/riscv/sfb.md
index 8ab747142c8..520b12c22f9 100644
--- a/gcc/config/riscv/sfb.md
+++ b/gcc/config/riscv/sfb.md
@@ -35,3 +35,35 @@
   [(set_attr "length" "8")
    (set_attr "type" "sfb_alu")
    (set_attr "mode" "<GPR:MODE>")])
+
+;; Combine creates this form ((typeof(y))zero_one * z) <op> y
+;; for SiFive short forward branches.
+
+(define_split
+  [(set (match_operand:X 0 "register_operand")
+	(and:X (sign_extract:X (match_operand:X 1 "register_operand")
+			       (const_int 1)
+			       (match_operand 2 "immediate_operand"))
+	       (match_operand:X 3 "register_operand")))
+   (clobber (match_operand:X 4 "register_operand"))]
+  "TARGET_SFB_ALU"
+  [(set (match_dup 4) (zero_extract:X (match_dup 1) (const_int 1) (match_dup 2)))
+   (set (match_dup 0) (if_then_else:X (ne:X (match_dup 4) (const_int 0))
+				      (match_dup 3)
+				      (const_int 0)))])
+
+(define_split
+  [(set (match_operand:X 0 "register_operand")
+	(and:X (sign_extract:X (match_operand:X 1 "register_operand")
+			       (const_int 1)
+			       (match_operand 2 "immediate_operand"))
+	       (match_operand:X 3 "register_operand")))
+   (clobber (match_operand:X 4 "register_operand"))]
+  "TARGET_SFB_ALU && (UINTVAL (operands[2]) < 11)"
+  [(set (match_dup 4) (and:X (match_dup 1) (match_dup 2)))
+   (set (match_dup 0) (if_then_else:X (ne:X (match_dup 4) (const_int 0))
+				      (match_dup 3)
+				      (const_int 0)))]
+{
+  operands[2] = GEN_INT (1 << UINTVAL(operands[2]));
+})
diff --git a/gcc/testsuite/gcc.target/riscv/sfb.c b/gcc/testsuite/gcc.target/riscv/sfb.c
new file mode 100644
index 00000000000..22f164051f4
--- /dev/null
+++ b/gcc/testsuite/gcc.target/riscv/sfb.c
@@ -0,0 +1,24 @@
+//* { dg-do compile } */
+/* { dg-options "-O2 -march=rv32gc -mabi=ilp32d -mtune=sifive-7-series" } */
+
+int f1(unsigned int x, unsigned int y, unsigned int z)
+{
+  return ((x & 1) == 0) ? y : z ^ y;
+}
+
+int f2(unsigned int x, unsigned int y, unsigned int z)
+{
+  return ((x & 1) != 0) ? z ^ y : y;
+}
+
+int f3(unsigned int x, unsigned int y, unsigned int z)
+{
+  return ((x & 1) == 0) ? y : z | y;
+}
+
+int f4(unsigned int x, unsigned int y, unsigned int z)
+{
+  return ((x & 1) != 0) ? z | y : y;
+}
+/* { dg-final { scan-assembler-times "bne" 4 } } */
+/* { dg-final { scan-assembler-times "movcc" 4 } } */
-- 
2.40.1

Re: [PATCH] RISC-V: Add split pattern to generate SFB instructions. [PR113095]

[Kito Cheng]

Thanks! generally LGTM, but I would wait one more week to see any
other comments :)

On Fri, Jan 19, 2024 at 3:05 PM Monk Chiang <monk.chiang@sifive.com> wrote:
>
> Since the match.pd transforms (zero_one == 0) ? y : z <op> y,
> into ((typeof(y))zero_one * z) <op> y. Add splitters to recongize
> this expression to generate SFB instructions.
>
> gcc/ChangeLog:
>         PR target/113095
>         * config/riscv/sfb.md: New splitters to rewrite single bit
>         sign extension as the condition to SFB instructions.
>
> gcc/testsuite/ChangeLog:
>         * gcc.target/riscv/sfb.c: New test.
> ---
>  gcc/config/riscv/sfb.md              | 32 ++++++++++++++++++++++++++++
>  gcc/testsuite/gcc.target/riscv/sfb.c | 24 +++++++++++++++++++++
>  2 files changed, 56 insertions(+)
>  create mode 100644 gcc/testsuite/gcc.target/riscv/sfb.c
>
> diff --git a/gcc/config/riscv/sfb.md b/gcc/config/riscv/sfb.md
> index 8ab747142c8..520b12c22f9 100644
> --- a/gcc/config/riscv/sfb.md
> +++ b/gcc/config/riscv/sfb.md
> @@ -35,3 +35,35 @@
>    [(set_attr "length" "8")
>     (set_attr "type" "sfb_alu")
>     (set_attr "mode" "<GPR:MODE>")])
> +
> +;; Combine creates this form ((typeof(y))zero_one * z) <op> y
> +;; for SiFive short forward branches.
> +
> +(define_split
> +  [(set (match_operand:X 0 "register_operand")
> +       (and:X (sign_extract:X (match_operand:X 1 "register_operand")
> +                              (const_int 1)
> +                              (match_operand 2 "immediate_operand"))
> +              (match_operand:X 3 "register_operand")))
> +   (clobber (match_operand:X 4 "register_operand"))]
> +  "TARGET_SFB_ALU"
> +  [(set (match_dup 4) (zero_extract:X (match_dup 1) (const_int 1) (match_dup 2)))
> +   (set (match_dup 0) (if_then_else:X (ne:X (match_dup 4) (const_int 0))
> +                                     (match_dup 3)
> +                                     (const_int 0)))])
> +
> +(define_split
> +  [(set (match_operand:X 0 "register_operand")
> +       (and:X (sign_extract:X (match_operand:X 1 "register_operand")
> +                              (const_int 1)
> +                              (match_operand 2 "immediate_operand"))
> +              (match_operand:X 3 "register_operand")))
> +   (clobber (match_operand:X 4 "register_operand"))]
> +  "TARGET_SFB_ALU && (UINTVAL (operands[2]) < 11)"
> +  [(set (match_dup 4) (and:X (match_dup 1) (match_dup 2)))
> +   (set (match_dup 0) (if_then_else:X (ne:X (match_dup 4) (const_int 0))
> +                                     (match_dup 3)
> +                                     (const_int 0)))]
> +{
> +  operands[2] = GEN_INT (1 << UINTVAL(operands[2]));
> +})
> diff --git a/gcc/testsuite/gcc.target/riscv/sfb.c b/gcc/testsuite/gcc.target/riscv/sfb.c
> new file mode 100644
> index 00000000000..22f164051f4
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/riscv/sfb.c
> @@ -0,0 +1,24 @@
> +//* { dg-do compile } */
> +/* { dg-options "-O2 -march=rv32gc -mabi=ilp32d -mtune=sifive-7-series" } */
> +
> +int f1(unsigned int x, unsigned int y, unsigned int z)
> +{
> +  return ((x & 1) == 0) ? y : z ^ y;
> +}
> +
> +int f2(unsigned int x, unsigned int y, unsigned int z)
> +{
> +  return ((x & 1) != 0) ? z ^ y : y;
> +}
> +
> +int f3(unsigned int x, unsigned int y, unsigned int z)
> +{
> +  return ((x & 1) == 0) ? y : z | y;
> +}
> +
> +int f4(unsigned int x, unsigned int y, unsigned int z)
> +{
> +  return ((x & 1) != 0) ? z | y : y;
> +}
> +/* { dg-final { scan-assembler-times "bne" 4 } } */
> +/* { dg-final { scan-assembler-times "movcc" 4 } } */
> --
> 2.40.1
>

Re: [PATCH] RISC-V: Add split pattern to generate SFB instructions. [PR113095]

[Jeff Law]

On 1/19/24 00:09, Kito Cheng wrote:
> Thanks! generally LGTM, but I would wait one more week to see any
> other comments :)Just a note.  113095 isn't marked as a regression, but it most 
definitely is a regression.  So this meets the stage4 criteria.


> 
> On Fri, Jan 19, 2024 at 3:05 PM Monk Chiang <monk.chiang@sifive.com> wrote:
>>
>> Since the match.pd transforms (zero_one == 0) ? y : z <op> y,
>> into ((typeof(y))zero_one * z) <op> y. Add splitters to recongize
>> this expression to generate SFB instructions.
>>
>> gcc/ChangeLog:
>>          PR target/113095
>>          * config/riscv/sfb.md: New splitters to rewrite single bit
>>          sign extension as the condition to SFB instructions.
>>
>> gcc/testsuite/ChangeLog:
>>          * gcc.target/riscv/sfb.c: New test.
I would probably suggest seeing if these still work when the NE nodes do 
not have a mode (ie, replace "ne:X" with just "ne".  Our docs are a bit 
unclear on that topic IIRC and it looks like the RISC-V backend is 
inconsistent.

More importantly, this message doesn't indicate if/how this patch was 
tested.  Given it's conditional on SFB a bug here would be narrow, but 
we should still be doing a regression test.

Jeff