* [x86_64 PATCH] More TImode parameter passing improvements.
@ 2023-07-19 20:07 Roger Sayle
2023-07-20 6:49 ` Uros Bizjak
0 siblings, 1 reply; 4+ messages in thread
From: Roger Sayle @ 2023-07-19 20:07 UTC (permalink / raw)
To: gcc-patches; +Cc: 'Uros Bizjak'
[-- Attachment #1: Type: text/plain, Size: 2759 bytes --]
This patch is the next piece of a solution to the x86_64 ABI issues in
PR 88873. This splits the *concat<mode><dwi>3_3 define_insn_and_split
into two patterns, a TARGET_64BIT *concatditi3_3 and a !TARGET_64BIT
*concatsidi3_3. This allows us to add an additional alternative to the
the 64-bit version, enabling the register allocator to perform this
operation using SSE registers, which is implemented/split after reload
using vec_concatv2di.
To demonstrate the improvement, the test case from PR88873:
typedef struct { double x, y; } s_t;
s_t foo (s_t a, s_t b, s_t c)
{
return (s_t){ __builtin_fma(a.x, b.x, c.x), __builtin_fma (a.y, b.y, c.y)
};
}
when compiled with -O2 -march=cascadelake, currently generates:
foo: vmovq %xmm2, -56(%rsp)
movq -56(%rsp), %rax
vmovq %xmm3, -48(%rsp)
vmovq %xmm4, -40(%rsp)
movq -48(%rsp), %rcx
vmovq %xmm5, -32(%rsp)
vmovq %rax, %xmm6
movq -40(%rsp), %rax
movq -32(%rsp), %rsi
vpinsrq $1, %rcx, %xmm6, %xmm6
vmovq %xmm0, -24(%rsp)
vmovq %rax, %xmm7
vmovq %xmm1, -16(%rsp)
vmovapd %xmm6, %xmm2
vpinsrq $1, %rsi, %xmm7, %xmm7
vfmadd132pd -24(%rsp), %xmm7, %xmm2
vmovapd %xmm2, -56(%rsp)
vmovsd -48(%rsp), %xmm1
vmovsd -56(%rsp), %xmm0
ret
with this change, we avoid many of the reloads via memory,
foo: vpunpcklqdq %xmm3, %xmm2, %xmm7
vpunpcklqdq %xmm1, %xmm0, %xmm6
vpunpcklqdq %xmm5, %xmm4, %xmm2
vmovdqa %xmm7, -24(%rsp)
vmovdqa %xmm6, %xmm1
movq -16(%rsp), %rax
vpinsrq $1, %rax, %xmm7, %xmm4
vmovapd %xmm4, %xmm6
vfmadd132pd %xmm1, %xmm2, %xmm6
vmovapd %xmm6, -24(%rsp)
vmovsd -16(%rsp), %xmm1
vmovsd -24(%rsp), %xmm0
ret
This patch has been tested on x86_64-pc-linux-gnu with make bootstrap
and make -k check, both with and without --target_board=unix{-m32}
with no new failures. Ok for mainline?
2023-07-19 Roger Sayle <roger@nextmovesoftware.com>
gcc/ChangeLog
* config/i386/i386-expand.cc (ix86_expand_move): Don't call
force_reg, to use SUBREG rather than create a new pseudo when
inserting DFmode fields into TImode with insvti_{high,low}part.
(*concat<mode><dwi>3_3): Split into two define_insn_and_split...
(*concatditi3_3): 64-bit implementation. Provide alternative
that allows register allocation to use SSE registers that is
split into vec_concatv2di after reload.
(*concatsidi3_3): 32-bit implementation.
gcc/testsuite/ChangeLog
* gcc.target/i386/pr88873.c: New test case.
Thanks in advance,
Roger
--
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diff --git a/gcc/config/i386/i386-expand.cc b/gcc/config/i386/i386-expand.cc
index f9b0dc6..9c3febe 100644
--- a/gcc/config/i386/i386-expand.cc
+++ b/gcc/config/i386/i386-expand.cc
@@ -558,7 +558,7 @@ ix86_expand_move (machine_mode mode, rtx operands[])
op0 = SUBREG_REG (op0);
tmp = gen_rtx_AND (TImode, copy_rtx (op0), tmp);
if (mode == DFmode)
- op1 = force_reg (DImode, gen_lowpart (DImode, op1));
+ op1 = gen_lowpart (DImode, op1);
op1 = gen_rtx_ZERO_EXTEND (TImode, op1);
op1 = gen_rtx_IOR (TImode, tmp, op1);
}
@@ -570,7 +570,7 @@ ix86_expand_move (machine_mode mode, rtx operands[])
op0 = SUBREG_REG (op0);
tmp = gen_rtx_AND (TImode, copy_rtx (op0), tmp);
if (mode == DFmode)
- op1 = force_reg (DImode, gen_lowpart (DImode, op1));
+ op1 = gen_lowpart (DImode, op1);
op1 = gen_rtx_ZERO_EXTEND (TImode, op1);
op1 = gen_rtx_ASHIFT (TImode, op1, GEN_INT (64));
op1 = gen_rtx_IOR (TImode, tmp, op1);
diff --git a/gcc/config/i386/i386.md b/gcc/config/i386/i386.md
index 47ea050..8c54aa5 100644
--- a/gcc/config/i386/i386.md
+++ b/gcc/config/i386/i386.md
@@ -12408,21 +12408,47 @@
DONE;
})
-(define_insn_and_split "*concat<mode><dwi>3_3"
- [(set (match_operand:<DWI> 0 "nonimmediate_operand" "=ro,r,r,&r")
- (any_or_plus:<DWI>
- (ashift:<DWI>
- (zero_extend:<DWI>
- (match_operand:DWIH 1 "nonimmediate_operand" "r,m,r,m"))
+(define_insn_and_split "*concatditi3_3"
+ [(set (match_operand:TI 0 "nonimmediate_operand" "=ro,r,r,&r,x")
+ (any_or_plus:TI
+ (ashift:TI
+ (zero_extend:TI
+ (match_operand:DI 1 "nonimmediate_operand" "r,m,r,m,x"))
(match_operand:QI 2 "const_int_operand"))
- (zero_extend:<DWI>
- (match_operand:DWIH 3 "nonimmediate_operand" "r,r,m,m"))))]
- "INTVAL (operands[2]) == <MODE_SIZE> * BITS_PER_UNIT"
+ (zero_extend:TI
+ (match_operand:DI 3 "nonimmediate_operand" "r,r,m,m,0"))))]
+ "TARGET_64BIT
+ && INTVAL (operands[2]) == 64"
+ "#"
+ "&& reload_completed"
+ [(const_int 0)]
+{
+ if (SSE_REG_P (operands[0]))
+ {
+ rtx tmp = gen_rtx_REG (V2DImode, REGNO (operands[0]));
+ emit_insn (gen_vec_concatv2di (tmp, operands[3], operands[1]));
+ }
+ else
+ split_double_concat (TImode, operands[0], operands[3], operands[1]);
+ DONE;
+})
+
+(define_insn_and_split "*concatsidi3_3"
+ [(set (match_operand:DI 0 "nonimmediate_operand" "=ro,r,r,&r")
+ (any_or_plus:DI
+ (ashift:DI
+ (zero_extend:DI
+ (match_operand:SI 1 "nonimmediate_operand" "r,m,r,m"))
+ (match_operand:QI 2 "const_int_operand"))
+ (zero_extend:DI
+ (match_operand:SI 3 "nonimmediate_operand" "r,r,m,m"))))]
+ "!TARGET_64BIT
+ && INTVAL (operands[2]) == 32"
"#"
"&& reload_completed"
[(const_int 0)]
{
- split_double_concat (<DWI>mode, operands[0], operands[3], operands[1]);
+ split_double_concat (DImode, operands[0], operands[3], operands[1]);
DONE;
})
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [x86_64 PATCH] More TImode parameter passing improvements.
2023-07-19 20:07 [x86_64 PATCH] More TImode parameter passing improvements Roger Sayle
@ 2023-07-20 6:49 ` Uros Bizjak
2023-07-20 7:44 ` Roger Sayle
0 siblings, 1 reply; 4+ messages in thread
From: Uros Bizjak @ 2023-07-20 6:49 UTC (permalink / raw)
To: Roger Sayle; +Cc: gcc-patches
On Wed, Jul 19, 2023 at 10:07 PM Roger Sayle <roger@nextmovesoftware.com> wrote:
>
>
> This patch is the next piece of a solution to the x86_64 ABI issues in
> PR 88873. This splits the *concat<mode><dwi>3_3 define_insn_and_split
> into two patterns, a TARGET_64BIT *concatditi3_3 and a !TARGET_64BIT
> *concatsidi3_3. This allows us to add an additional alternative to the
> the 64-bit version, enabling the register allocator to perform this
> operation using SSE registers, which is implemented/split after reload
> using vec_concatv2di.
>
> To demonstrate the improvement, the test case from PR88873:
>
> typedef struct { double x, y; } s_t;
>
> s_t foo (s_t a, s_t b, s_t c)
> {
> return (s_t){ __builtin_fma(a.x, b.x, c.x), __builtin_fma (a.y, b.y, c.y)
> };
> }
>
> when compiled with -O2 -march=cascadelake, currently generates:
>
> foo: vmovq %xmm2, -56(%rsp)
> movq -56(%rsp), %rax
> vmovq %xmm3, -48(%rsp)
> vmovq %xmm4, -40(%rsp)
> movq -48(%rsp), %rcx
> vmovq %xmm5, -32(%rsp)
> vmovq %rax, %xmm6
> movq -40(%rsp), %rax
> movq -32(%rsp), %rsi
> vpinsrq $1, %rcx, %xmm6, %xmm6
> vmovq %xmm0, -24(%rsp)
> vmovq %rax, %xmm7
> vmovq %xmm1, -16(%rsp)
> vmovapd %xmm6, %xmm2
> vpinsrq $1, %rsi, %xmm7, %xmm7
> vfmadd132pd -24(%rsp), %xmm7, %xmm2
> vmovapd %xmm2, -56(%rsp)
> vmovsd -48(%rsp), %xmm1
> vmovsd -56(%rsp), %xmm0
> ret
>
> with this change, we avoid many of the reloads via memory,
>
> foo: vpunpcklqdq %xmm3, %xmm2, %xmm7
> vpunpcklqdq %xmm1, %xmm0, %xmm6
> vpunpcklqdq %xmm5, %xmm4, %xmm2
> vmovdqa %xmm7, -24(%rsp)
> vmovdqa %xmm6, %xmm1
> movq -16(%rsp), %rax
> vpinsrq $1, %rax, %xmm7, %xmm4
> vmovapd %xmm4, %xmm6
> vfmadd132pd %xmm1, %xmm2, %xmm6
> vmovapd %xmm6, -24(%rsp)
> vmovsd -16(%rsp), %xmm1
> vmovsd -24(%rsp), %xmm0
> ret
>
>
> This patch has been tested on x86_64-pc-linux-gnu with make bootstrap
> and make -k check, both with and without --target_board=unix{-m32}
> with no new failures. Ok for mainline?
>
>
> 2023-07-19 Roger Sayle <roger@nextmovesoftware.com>
>
> gcc/ChangeLog
> * config/i386/i386-expand.cc (ix86_expand_move): Don't call
> force_reg, to use SUBREG rather than create a new pseudo when
> inserting DFmode fields into TImode with insvti_{high,low}part.
> (*concat<mode><dwi>3_3): Split into two define_insn_and_split...
> (*concatditi3_3): 64-bit implementation. Provide alternative
> that allows register allocation to use SSE registers that is
> split into vec_concatv2di after reload.
> (*concatsidi3_3): 32-bit implementation.
>
> gcc/testsuite/ChangeLog
> * gcc.target/i386/pr88873.c: New test case.
diff --git a/gcc/config/i386/i386-expand.cc b/gcc/config/i386/i386-expand.cc
index f9b0dc6..9c3febe 100644
--- a/gcc/config/i386/i386-expand.cc
+++ b/gcc/config/i386/i386-expand.cc
@@ -558,7 +558,7 @@ ix86_expand_move (machine_mode mode, rtx operands[])
op0 = SUBREG_REG (op0);
tmp = gen_rtx_AND (TImode, copy_rtx (op0), tmp);
if (mode == DFmode)
- op1 = force_reg (DImode, gen_lowpart (DImode, op1));
+ op1 = gen_lowpart (DImode, op1);
Please note that gen_lowpart will ICE when op1 is a SUBREG. This is
the reason that we need to first force a SUBREG to a register and then
perform gen_lowpart, and it is necessary to avoid ICE.
op1 = gen_rtx_ZERO_EXTEND (TImode, op1);
op1 = gen_rtx_IOR (TImode, tmp, op1);
}
@@ -570,7 +570,7 @@ ix86_expand_move (machine_mode mode, rtx operands[])
op0 = SUBREG_REG (op0);
tmp = gen_rtx_AND (TImode, copy_rtx (op0), tmp);
if (mode == DFmode)
- op1 = force_reg (DImode, gen_lowpart (DImode, op1));
+ op1 = gen_lowpart (DImode, op1);
Also here.
op1 = gen_rtx_ZERO_EXTEND (TImode, op1);
op1 = gen_rtx_ASHIFT (TImode, op1, GEN_INT (64));
op1 = gen_rtx_IOR (TImode, tmp, op1);
Uros.
^ permalink raw reply [flat|nested] 4+ messages in thread
* RE: [x86_64 PATCH] More TImode parameter passing improvements.
2023-07-20 6:49 ` Uros Bizjak
@ 2023-07-20 7:44 ` Roger Sayle
2023-07-20 7:49 ` Uros Bizjak
0 siblings, 1 reply; 4+ messages in thread
From: Roger Sayle @ 2023-07-20 7:44 UTC (permalink / raw)
To: 'Uros Bizjak'; +Cc: gcc-patches
Hi Uros,
> From: Uros Bizjak <ubizjak@gmail.com>
> Sent: 20 July 2023 07:50
>
> On Wed, Jul 19, 2023 at 10:07 PM Roger Sayle <roger@nextmovesoftware.com>
> wrote:
> >
> > This patch is the next piece of a solution to the x86_64 ABI issues in
> > PR 88873. This splits the *concat<mode><dwi>3_3 define_insn_and_split
> > into two patterns, a TARGET_64BIT *concatditi3_3 and a !TARGET_64BIT
> > *concatsidi3_3. This allows us to add an additional alternative to
> > the the 64-bit version, enabling the register allocator to perform
> > this operation using SSE registers, which is implemented/split after
> > reload using vec_concatv2di.
> >
> > To demonstrate the improvement, the test case from PR88873:
> >
> > typedef struct { double x, y; } s_t;
> >
> > s_t foo (s_t a, s_t b, s_t c)
> > {
> > return (s_t){ __builtin_fma(a.x, b.x, c.x), __builtin_fma (a.y, b.y,
> > c.y) }; }
> >
> > when compiled with -O2 -march=cascadelake, currently generates:
> >
> > foo: vmovq %xmm2, -56(%rsp)
> > movq -56(%rsp), %rax
> > vmovq %xmm3, -48(%rsp)
> > vmovq %xmm4, -40(%rsp)
> > movq -48(%rsp), %rcx
> > vmovq %xmm5, -32(%rsp)
> > vmovq %rax, %xmm6
> > movq -40(%rsp), %rax
> > movq -32(%rsp), %rsi
> > vpinsrq $1, %rcx, %xmm6, %xmm6
> > vmovq %xmm0, -24(%rsp)
> > vmovq %rax, %xmm7
> > vmovq %xmm1, -16(%rsp)
> > vmovapd %xmm6, %xmm2
> > vpinsrq $1, %rsi, %xmm7, %xmm7
> > vfmadd132pd -24(%rsp), %xmm7, %xmm2
> > vmovapd %xmm2, -56(%rsp)
> > vmovsd -48(%rsp), %xmm1
> > vmovsd -56(%rsp), %xmm0
> > ret
> >
> > with this change, we avoid many of the reloads via memory,
> >
> > foo: vpunpcklqdq %xmm3, %xmm2, %xmm7
> > vpunpcklqdq %xmm1, %xmm0, %xmm6
> > vpunpcklqdq %xmm5, %xmm4, %xmm2
> > vmovdqa %xmm7, -24(%rsp)
> > vmovdqa %xmm6, %xmm1
> > movq -16(%rsp), %rax
> > vpinsrq $1, %rax, %xmm7, %xmm4
> > vmovapd %xmm4, %xmm6
> > vfmadd132pd %xmm1, %xmm2, %xmm6
> > vmovapd %xmm6, -24(%rsp)
> > vmovsd -16(%rsp), %xmm1
> > vmovsd -24(%rsp), %xmm0
> > ret
> >
> >
> > This patch has been tested on x86_64-pc-linux-gnu with make bootstrap
> > and make -k check, both with and without --target_board=unix{-m32}
> > with no new failures. Ok for mainline?
> >
> >
> > 2023-07-19 Roger Sayle <roger@nextmovesoftware.com>
> >
> > gcc/ChangeLog
> > * config/i386/i386-expand.cc (ix86_expand_move): Don't call
> > force_reg, to use SUBREG rather than create a new pseudo when
> > inserting DFmode fields into TImode with insvti_{high,low}part.
> > (*concat<mode><dwi>3_3): Split into two define_insn_and_split...
> > (*concatditi3_3): 64-bit implementation. Provide alternative
> > that allows register allocation to use SSE registers that is
> > split into vec_concatv2di after reload.
> > (*concatsidi3_3): 32-bit implementation.
> >
> > gcc/testsuite/ChangeLog
> > * gcc.target/i386/pr88873.c: New test case.
>
> diff --git a/gcc/config/i386/i386-expand.cc b/gcc/config/i386/i386-expand.cc
> index f9b0dc6..9c3febe 100644
> --- a/gcc/config/i386/i386-expand.cc
> +++ b/gcc/config/i386/i386-expand.cc
> @@ -558,7 +558,7 @@ ix86_expand_move (machine_mode mode, rtx
> operands[])
> op0 = SUBREG_REG (op0);
> tmp = gen_rtx_AND (TImode, copy_rtx (op0), tmp);
> if (mode == DFmode)
> - op1 = force_reg (DImode, gen_lowpart (DImode, op1));
> + op1 = gen_lowpart (DImode, op1);
>
> Please note that gen_lowpart will ICE when op1 is a SUBREG. This is the reason
> that we need to first force a SUBREG to a register and then perform gen_lowpart,
> and it is necessary to avoid ICE.
The good news is that we know op1 is a register, as this is tested by
"&& REG_P (op1)" on line 551. You'll also notice that I'm not removing
the force_reg from before the call to gen_lowpart, but removing the call
to force_reg after the call to gen_lowpart. When I originally wrote this,
the hope was that placing this SUBREG in its own pseudo would help
with register allocation/CSE. Unfortunately, increasing the number of
pseudos (in this case) increases compile-time (due to quadratic behaviour
in LRA), as shown by PR rtl-optimization/110587, and keeping the DF->DI
conversion in a SUBREG inside the insvti_{high,low}part allows the
register allocator to see the DF->DI->TI sequence in a single pattern,
and hence choose to keep the TI mode in SSE registers, rather than use
a pair of reloads, to write the DF value to memory, then read it back as
a scalar in DImode, and perhaps the same again to go the other way.
> op1 = gen_rtx_ZERO_EXTEND (TImode, op1);
> op1 = gen_rtx_IOR (TImode, tmp, op1);
> }
> @@ -570,7 +570,7 @@ ix86_expand_move (machine_mode mode, rtx
> operands[])
> op0 = SUBREG_REG (op0);
> tmp = gen_rtx_AND (TImode, copy_rtx (op0), tmp);
> if (mode == DFmode)
> - op1 = force_reg (DImode, gen_lowpart (DImode, op1));
> + op1 = gen_lowpart (DImode, op1);
>
> Also here.
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [x86_64 PATCH] More TImode parameter passing improvements.
2023-07-20 7:44 ` Roger Sayle
@ 2023-07-20 7:49 ` Uros Bizjak
0 siblings, 0 replies; 4+ messages in thread
From: Uros Bizjak @ 2023-07-20 7:49 UTC (permalink / raw)
To: Roger Sayle; +Cc: gcc-patches
On Thu, Jul 20, 2023 at 9:44 AM Roger Sayle <roger@nextmovesoftware.com> wrote:
>
>
> Hi Uros,
>
> > From: Uros Bizjak <ubizjak@gmail.com>
> > Sent: 20 July 2023 07:50
> >
> > On Wed, Jul 19, 2023 at 10:07 PM Roger Sayle <roger@nextmovesoftware.com>
> > wrote:
> > >
> > > This patch is the next piece of a solution to the x86_64 ABI issues in
> > > PR 88873. This splits the *concat<mode><dwi>3_3 define_insn_and_split
> > > into two patterns, a TARGET_64BIT *concatditi3_3 and a !TARGET_64BIT
> > > *concatsidi3_3. This allows us to add an additional alternative to
> > > the the 64-bit version, enabling the register allocator to perform
> > > this operation using SSE registers, which is implemented/split after
> > > reload using vec_concatv2di.
> > >
> > > To demonstrate the improvement, the test case from PR88873:
> > >
> > > typedef struct { double x, y; } s_t;
> > >
> > > s_t foo (s_t a, s_t b, s_t c)
> > > {
> > > return (s_t){ __builtin_fma(a.x, b.x, c.x), __builtin_fma (a.y, b.y,
> > > c.y) }; }
> > >
> > > when compiled with -O2 -march=cascadelake, currently generates:
> > >
> > > foo: vmovq %xmm2, -56(%rsp)
> > > movq -56(%rsp), %rax
> > > vmovq %xmm3, -48(%rsp)
> > > vmovq %xmm4, -40(%rsp)
> > > movq -48(%rsp), %rcx
> > > vmovq %xmm5, -32(%rsp)
> > > vmovq %rax, %xmm6
> > > movq -40(%rsp), %rax
> > > movq -32(%rsp), %rsi
> > > vpinsrq $1, %rcx, %xmm6, %xmm6
> > > vmovq %xmm0, -24(%rsp)
> > > vmovq %rax, %xmm7
> > > vmovq %xmm1, -16(%rsp)
> > > vmovapd %xmm6, %xmm2
> > > vpinsrq $1, %rsi, %xmm7, %xmm7
> > > vfmadd132pd -24(%rsp), %xmm7, %xmm2
> > > vmovapd %xmm2, -56(%rsp)
> > > vmovsd -48(%rsp), %xmm1
> > > vmovsd -56(%rsp), %xmm0
> > > ret
> > >
> > > with this change, we avoid many of the reloads via memory,
> > >
> > > foo: vpunpcklqdq %xmm3, %xmm2, %xmm7
> > > vpunpcklqdq %xmm1, %xmm0, %xmm6
> > > vpunpcklqdq %xmm5, %xmm4, %xmm2
> > > vmovdqa %xmm7, -24(%rsp)
> > > vmovdqa %xmm6, %xmm1
> > > movq -16(%rsp), %rax
> > > vpinsrq $1, %rax, %xmm7, %xmm4
> > > vmovapd %xmm4, %xmm6
> > > vfmadd132pd %xmm1, %xmm2, %xmm6
> > > vmovapd %xmm6, -24(%rsp)
> > > vmovsd -16(%rsp), %xmm1
> > > vmovsd -24(%rsp), %xmm0
> > > ret
> > >
> > >
> > > This patch has been tested on x86_64-pc-linux-gnu with make bootstrap
> > > and make -k check, both with and without --target_board=unix{-m32}
> > > with no new failures. Ok for mainline?
> > >
> > >
> > > 2023-07-19 Roger Sayle <roger@nextmovesoftware.com>
> > >
> > > gcc/ChangeLog
> > > * config/i386/i386-expand.cc (ix86_expand_move): Don't call
> > > force_reg, to use SUBREG rather than create a new pseudo when
> > > inserting DFmode fields into TImode with insvti_{high,low}part.
> > > (*concat<mode><dwi>3_3): Split into two define_insn_and_split...
> > > (*concatditi3_3): 64-bit implementation. Provide alternative
> > > that allows register allocation to use SSE registers that is
> > > split into vec_concatv2di after reload.
> > > (*concatsidi3_3): 32-bit implementation.
> > >
> > > gcc/testsuite/ChangeLog
> > > * gcc.target/i386/pr88873.c: New test case.
> >
> > diff --git a/gcc/config/i386/i386-expand.cc b/gcc/config/i386/i386-expand.cc
> > index f9b0dc6..9c3febe 100644
> > --- a/gcc/config/i386/i386-expand.cc
> > +++ b/gcc/config/i386/i386-expand.cc
> > @@ -558,7 +558,7 @@ ix86_expand_move (machine_mode mode, rtx
> > operands[])
> > op0 = SUBREG_REG (op0);
> > tmp = gen_rtx_AND (TImode, copy_rtx (op0), tmp);
> > if (mode == DFmode)
> > - op1 = force_reg (DImode, gen_lowpart (DImode, op1));
> > + op1 = gen_lowpart (DImode, op1);
> >
> > Please note that gen_lowpart will ICE when op1 is a SUBREG. This is the reason
> > that we need to first force a SUBREG to a register and then perform gen_lowpart,
> > and it is necessary to avoid ICE.
>
> The good news is that we know op1 is a register, as this is tested by
> "&& REG_P (op1)" on line 551. You'll also notice that I'm not removing
> the force_reg from before the call to gen_lowpart, but removing the call
> to force_reg after the call to gen_lowpart. When I originally wrote this,
> the hope was that placing this SUBREG in its own pseudo would help
> with register allocation/CSE. Unfortunately, increasing the number of
> pseudos (in this case) increases compile-time (due to quadratic behaviour
> in LRA), as shown by PR rtl-optimization/110587, and keeping the DF->DI
> conversion in a SUBREG inside the insvti_{high,low}part allows the
> register allocator to see the DF->DI->TI sequence in a single pattern,
> and hence choose to keep the TI mode in SSE registers, rather than use
> a pair of reloads, to write the DF value to memory, then read it back as
> a scalar in DImode, and perhaps the same again to go the other way.
This was my only concern with the patch, with that cleared, the patch is OK.
Thanks,
Uros.
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2023-07-19 20:07 [x86_64 PATCH] More TImode parameter passing improvements Roger Sayle
2023-07-20 6:49 ` Uros Bizjak
2023-07-20 7:44 ` Roger Sayle
2023-07-20 7:49 ` Uros Bizjak
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