* [PATCH] Reduce cost of MEM (A + imm).
@ 2024-05-28 2:46 liuhongt
2024-05-28 6:13 ` Uros Bizjak
0 siblings, 1 reply; 4+ messages in thread
From: liuhongt @ 2024-05-28 2:46 UTC (permalink / raw)
To: gcc-patches; +Cc: ubizjak
For MEM, rtx_cost iterates each subrtx, and adds up the costs,
so for MEM (reg) and MEM (reg + 4), the former costs 5,
the latter costs 9, it is not accurate for x86. Ideally
address_cost should be used, but it reduce cost too much.
So current solution is make constant disp as cheap as possible.
Bootstrapped and regtested on x86_64-pc-linux-gnu{-m32,}.
Ok for trunk?
gcc/ChangeLog:
PR target/67325
* config/i386/i386.cc (ix86_rtx_costs): Reduce cost of MEM (A
+ imm) to "cost of MEM (A)" + 1.
gcc/testsuite/ChangeLog:
* gcc.target/i386/pr67325.c: New test.
---
gcc/config/i386/i386.cc | 19 ++++++++++++++++++-
gcc/testsuite/gcc.target/i386/pr67325.c | 7 +++++++
2 files changed, 25 insertions(+), 1 deletion(-)
create mode 100644 gcc/testsuite/gcc.target/i386/pr67325.c
diff --git a/gcc/config/i386/i386.cc b/gcc/config/i386/i386.cc
index 3e2a3a194f1..3936223bd20 100644
--- a/gcc/config/i386/i386.cc
+++ b/gcc/config/i386/i386.cc
@@ -22194,7 +22194,24 @@ ix86_rtx_costs (rtx x, machine_mode mode, int outer_code_i, int opno,
/* An insn that accesses memory is slightly more expensive
than one that does not. */
if (speed)
- *total += 1;
+ {
+ *total += 1;
+ rtx addr = XEXP (x, 0);
+ /* For MEM, rtx_cost iterates each subrtx, and adds up the costs,
+ so for MEM (reg) and MEM (reg + 4), the former costs 5,
+ the latter costs 9, it is not accurate for x86. Ideally
+ address_cost should be used, but it reduce cost too much.
+ So current solution is make constant disp as cheap as possible. */
+ if (GET_CODE (addr) == PLUS
+ && CONST_INT_P (XEXP (addr, 1))
+ && x86_64_immediate_operand (XEXP (addr, 1), Pmode))
+ {
+ *total += 1;
+ *total += rtx_cost (XEXP (addr, 0), Pmode, PLUS, 0, speed);
+ return true;
+ }
+ }
+
return false;
case ZERO_EXTRACT:
diff --git a/gcc/testsuite/gcc.target/i386/pr67325.c b/gcc/testsuite/gcc.target/i386/pr67325.c
new file mode 100644
index 00000000000..c3c1e4c5b4d
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr67325.c
@@ -0,0 +1,7 @@
+/* { dg-do compile { target { ! ia32 } } } */
+/* { dg-options "-O2" } */
+/* { dg-final { scan-assembler-not "(?:sar|shr)" } } */
+
+int f(long*l){
+ return *l>>32;
+}
--
2.31.1
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] Reduce cost of MEM (A + imm).
2024-05-28 2:46 [PATCH] Reduce cost of MEM (A + imm) liuhongt
@ 2024-05-28 6:13 ` Uros Bizjak
2024-05-28 10:45 ` [PATCH V2] " liuhongt
0 siblings, 1 reply; 4+ messages in thread
From: Uros Bizjak @ 2024-05-28 6:13 UTC (permalink / raw)
To: liuhongt; +Cc: gcc-patches
On Tue, May 28, 2024 at 4:48 AM liuhongt <hongtao.liu@intel.com> wrote:
>
> For MEM, rtx_cost iterates each subrtx, and adds up the costs,
> so for MEM (reg) and MEM (reg + 4), the former costs 5,
> the latter costs 9, it is not accurate for x86. Ideally
> address_cost should be used, but it reduce cost too much.
> So current solution is make constant disp as cheap as possible.
>
> Bootstrapped and regtested on x86_64-pc-linux-gnu{-m32,}.
> Ok for trunk?
>
> gcc/ChangeLog:
>
> PR target/67325
> * config/i386/i386.cc (ix86_rtx_costs): Reduce cost of MEM (A
> + imm) to "cost of MEM (A)" + 1.
>
> gcc/testsuite/ChangeLog:
>
> * gcc.target/i386/pr67325.c: New test.
> ---
> gcc/config/i386/i386.cc | 19 ++++++++++++++++++-
> gcc/testsuite/gcc.target/i386/pr67325.c | 7 +++++++
> 2 files changed, 25 insertions(+), 1 deletion(-)
> create mode 100644 gcc/testsuite/gcc.target/i386/pr67325.c
>
> diff --git a/gcc/config/i386/i386.cc b/gcc/config/i386/i386.cc
> index 3e2a3a194f1..3936223bd20 100644
> --- a/gcc/config/i386/i386.cc
> +++ b/gcc/config/i386/i386.cc
> @@ -22194,7 +22194,24 @@ ix86_rtx_costs (rtx x, machine_mode mode, int outer_code_i, int opno,
> /* An insn that accesses memory is slightly more expensive
> than one that does not. */
> if (speed)
> - *total += 1;
> + {
> + *total += 1;
> + rtx addr = XEXP (x, 0);
> + /* For MEM, rtx_cost iterates each subrtx, and adds up the costs,
> + so for MEM (reg) and MEM (reg + 4), the former costs 5,
> + the latter costs 9, it is not accurate for x86. Ideally
> + address_cost should be used, but it reduce cost too much.
> + So current solution is make constant disp as cheap as possible. */
> + if (GET_CODE (addr) == PLUS
> + && CONST_INT_P (XEXP (addr, 1))
IMO, there is no need for CONST_INT_P condition, we should also allow
symbol_ref, label_ref and const (all allowed by
x86_64_immediate_operand predicate), these all decay to an immediate
value.
Uros.
> + && x86_64_immediate_operand (XEXP (addr, 1), Pmode))
> + {
> + *total += 1;
> + *total += rtx_cost (XEXP (addr, 0), Pmode, PLUS, 0, speed);
> + return true;
> + }
> + }
> +
> return false;
>
> case ZERO_EXTRACT:
> diff --git a/gcc/testsuite/gcc.target/i386/pr67325.c b/gcc/testsuite/gcc.target/i386/pr67325.c
> new file mode 100644
> index 00000000000..c3c1e4c5b4d
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/i386/pr67325.c
> @@ -0,0 +1,7 @@
> +/* { dg-do compile { target { ! ia32 } } } */
> +/* { dg-options "-O2" } */
> +/* { dg-final { scan-assembler-not "(?:sar|shr)" } } */
> +
> +int f(long*l){
> + return *l>>32;
> +}
> --
> 2.31.1
>
^ permalink raw reply [flat|nested] 4+ messages in thread
* [PATCH V2] Reduce cost of MEM (A + imm).
2024-05-28 6:13 ` Uros Bizjak
@ 2024-05-28 10:45 ` liuhongt
2024-05-28 12:04 ` Uros Bizjak
0 siblings, 1 reply; 4+ messages in thread
From: liuhongt @ 2024-05-28 10:45 UTC (permalink / raw)
To: gcc-patches; +Cc: ubizjak
> IMO, there is no need for CONST_INT_P condition, we should also allow
> symbol_ref, label_ref and const (all allowed by
> x86_64_immediate_operand predicate), these all decay to an immediate
> value.
Changed.
Bootstrapped and regtested on x86_64-pc-linux-gnu{-m32,}.
Ok for trunk.
For MEM, rtx_cost iterates each subrtx, and adds up the costs,
so for MEM (reg) and MEM (reg + 4), the former costs 5,
the latter costs 9, it is not accurate for x86. Ideally
address_cost should be used, but it reduce cost too much.
So current solution is make constant disp as cheap as possible.
gcc/ChangeLog:
PR target/67325
* config/i386/i386.cc (ix86_rtx_costs): Reduce cost of MEM (A
+ imm) to "cost of MEM (A)" + 1.
gcc/testsuite/ChangeLog:
* gcc.target/i386/pr67325.c: New test.
---
gcc/config/i386/i386.cc | 18 +++++++++++++++++-
gcc/testsuite/gcc.target/i386/pr67325.c | 7 +++++++
2 files changed, 24 insertions(+), 1 deletion(-)
create mode 100644 gcc/testsuite/gcc.target/i386/pr67325.c
diff --git a/gcc/config/i386/i386.cc b/gcc/config/i386/i386.cc
index 3e2a3a194f1..85d87b9f778 100644
--- a/gcc/config/i386/i386.cc
+++ b/gcc/config/i386/i386.cc
@@ -22194,7 +22194,23 @@ ix86_rtx_costs (rtx x, machine_mode mode, int outer_code_i, int opno,
/* An insn that accesses memory is slightly more expensive
than one that does not. */
if (speed)
- *total += 1;
+ {
+ *total += 1;
+ rtx addr = XEXP (x, 0);
+ /* For MEM, rtx_cost iterates each subrtx, and adds up the costs,
+ so for MEM (reg) and MEM (reg + 4), the former costs 5,
+ the latter costs 9, it is not accurate for x86. Ideally
+ address_cost should be used, but it reduce cost too much.
+ So current solution is make constant disp as cheap as possible. */
+ if (GET_CODE (addr) == PLUS
+ && x86_64_immediate_operand (XEXP (addr, 1), Pmode))
+ {
+ *total += 1;
+ *total += rtx_cost (XEXP (addr, 0), Pmode, PLUS, 0, speed);
+ return true;
+ }
+ }
+
return false;
case ZERO_EXTRACT:
diff --git a/gcc/testsuite/gcc.target/i386/pr67325.c b/gcc/testsuite/gcc.target/i386/pr67325.c
new file mode 100644
index 00000000000..c3c1e4c5b4d
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr67325.c
@@ -0,0 +1,7 @@
+/* { dg-do compile { target { ! ia32 } } } */
+/* { dg-options "-O2" } */
+/* { dg-final { scan-assembler-not "(?:sar|shr)" } } */
+
+int f(long*l){
+ return *l>>32;
+}
--
2.31.1
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH V2] Reduce cost of MEM (A + imm).
2024-05-28 10:45 ` [PATCH V2] " liuhongt
@ 2024-05-28 12:04 ` Uros Bizjak
0 siblings, 0 replies; 4+ messages in thread
From: Uros Bizjak @ 2024-05-28 12:04 UTC (permalink / raw)
To: liuhongt; +Cc: gcc-patches
On Tue, May 28, 2024 at 12:48 PM liuhongt <hongtao.liu@intel.com> wrote:
>
> > IMO, there is no need for CONST_INT_P condition, we should also allow
> > symbol_ref, label_ref and const (all allowed by
> > x86_64_immediate_operand predicate), these all decay to an immediate
> > value.
>
> Changed.
>
> Bootstrapped and regtested on x86_64-pc-linux-gnu{-m32,}.
> Ok for trunk.
>
> For MEM, rtx_cost iterates each subrtx, and adds up the costs,
> so for MEM (reg) and MEM (reg + 4), the former costs 5,
> the latter costs 9, it is not accurate for x86. Ideally
> address_cost should be used, but it reduce cost too much.
> So current solution is make constant disp as cheap as possible.
>
> gcc/ChangeLog:
>
> PR target/67325
> * config/i386/i386.cc (ix86_rtx_costs): Reduce cost of MEM (A
> + imm) to "cost of MEM (A)" + 1.
>
> gcc/testsuite/ChangeLog:
>
> * gcc.target/i386/pr67325.c: New test.
OK.
Thanks,
Uros.
> ---
> gcc/config/i386/i386.cc | 18 +++++++++++++++++-
> gcc/testsuite/gcc.target/i386/pr67325.c | 7 +++++++
> 2 files changed, 24 insertions(+), 1 deletion(-)
> create mode 100644 gcc/testsuite/gcc.target/i386/pr67325.c
>
> diff --git a/gcc/config/i386/i386.cc b/gcc/config/i386/i386.cc
> index 3e2a3a194f1..85d87b9f778 100644
> --- a/gcc/config/i386/i386.cc
> +++ b/gcc/config/i386/i386.cc
> @@ -22194,7 +22194,23 @@ ix86_rtx_costs (rtx x, machine_mode mode, int outer_code_i, int opno,
> /* An insn that accesses memory is slightly more expensive
> than one that does not. */
> if (speed)
> - *total += 1;
> + {
> + *total += 1;
> + rtx addr = XEXP (x, 0);
> + /* For MEM, rtx_cost iterates each subrtx, and adds up the costs,
> + so for MEM (reg) and MEM (reg + 4), the former costs 5,
> + the latter costs 9, it is not accurate for x86. Ideally
> + address_cost should be used, but it reduce cost too much.
> + So current solution is make constant disp as cheap as possible. */
> + if (GET_CODE (addr) == PLUS
> + && x86_64_immediate_operand (XEXP (addr, 1), Pmode))
> + {
> + *total += 1;
> + *total += rtx_cost (XEXP (addr, 0), Pmode, PLUS, 0, speed);
> + return true;
> + }
> + }
> +
> return false;
>
> case ZERO_EXTRACT:
> diff --git a/gcc/testsuite/gcc.target/i386/pr67325.c b/gcc/testsuite/gcc.target/i386/pr67325.c
> new file mode 100644
> index 00000000000..c3c1e4c5b4d
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/i386/pr67325.c
> @@ -0,0 +1,7 @@
> +/* { dg-do compile { target { ! ia32 } } } */
> +/* { dg-options "-O2" } */
> +/* { dg-final { scan-assembler-not "(?:sar|shr)" } } */
> +
> +int f(long*l){
> + return *l>>32;
> +}
> --
> 2.31.1
>
^ permalink raw reply [flat|nested] 4+ messages in thread
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2024-05-28 2:46 [PATCH] Reduce cost of MEM (A + imm) liuhongt
2024-05-28 6:13 ` Uros Bizjak
2024-05-28 10:45 ` [PATCH V2] " liuhongt
2024-05-28 12:04 ` Uros Bizjak
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