This is the next piece towards a fix for (the x86_64 ABI issues affecting)
PR 88873. This patch generalizes the recent tweak to ix86_expand_move
for setting the highpart of a TImode reg from a DImode source using
*insvti_highpart_1, to handle both DImode and DFmode sources, and also
use the recently added *insvti_lowpart_1 for setting the lowpart.
Although this is another intermediate step (not yet a fix), towards
enabling *insvti and *concat* patterns to be candidates for TImode STV
(by using V2DI/V2DF instructions), it already improves things a little.
For the test case from PR 88873
typedef struct { double x, y; } s_t;
typedef double v2df __attribute__ ((vector_size (2 * sizeof(double;
s_t foo (s_t a, s_t b, s_t c)
{
return (s_t) { fma(a.x, b.x, c.x), fma (a.y, b.y, c.y) };
}
With -O2 -march=cascadelake, GCC currently generates:
Before (29 instructions):
vmovq %xmm2, -56(%rsp)
movq-56(%rsp), %rdx
vmovq %xmm4, -40(%rsp)
movq$0, -48(%rsp)
movq%rdx, -56(%rsp)
movq-40(%rsp), %rdx
vmovq %xmm0, -24(%rsp)
movq%rdx, -40(%rsp)
movq-24(%rsp), %rsi
movq-56(%rsp), %rax
movq$0, -32(%rsp)
vmovq %xmm3, -48(%rsp)
movq-48(%rsp), %rcx
vmovq %xmm5, -32(%rsp)
vmovq %rax, %xmm6
movq-40(%rsp), %rax
movq$0, -16(%rsp)
movq%rsi, -24(%rsp)
movq-32(%rsp), %rsi
vpinsrq $1, %rcx, %xmm6, %xmm6
vmovq %rax, %xmm7
vmovq %xmm1, -16(%rsp)
vmovapd %xmm6, %xmm3
vpinsrq $1, %rsi, %xmm7, %xmm7
vfmadd132pd -24(%rsp), %xmm7, %xmm3
vmovapd %xmm3, -56(%rsp)
vmovsd -48(%rsp), %xmm1
vmovsd -56(%rsp), %xmm0
ret
After (20 instructions):
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
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. No testcase yet, as the above code will hopefully
change dramatically with the next pieces. Ok for mainline?
2023-07-13 Roger Sayle
gcc/ChangeLog
* config/i386/i386-expand.cc (ix86_expand_move): Generalize special
case inserting of 64-bit values into a TImode register, to handle
both DImode and DFmode using either *insvti_lowpart_1
or *isnvti_highpart_1.
Thanks again,
Roger
--
diff --git a/gcc/config/i386/i386-expand.cc b/gcc/config/i386/i386-expand.cc
index 92ffa4b..fe87f8e 100644
--- a/gcc/config/i386/i386-expand.cc
+++ b/gcc/config/i386/i386-expand.cc
@@ -542,22 +542,39 @@ ix86_expand_move (machine_mode mode, rtx operands[])
}
}
- /* Use *insvti_highpart_1 to set highpart of TImode register. */
+ /* Special case inserting 64-bit values into a TImode register. */
if (TARGET_64BIT
- && mode == DImode
+ && (mode == DImode || mode == DFmode)
&& SUBREG_P (op0)
- && SUBREG_BYTE (op0) == 8
&& GET_MODE (SUBREG_REG (op0)) == TImode
&& REG_P (SUBREG_REG (op0))
&& REG_P (op1))
{
- wide_int mask = wi::mask (64, false, 128);
- rtx tmp = immed_wide_int_const (mask, TImode);
- op0 = SUBREG_REG (op0);
- tmp = gen_rtx_AND (TImode, copy_rtx (op0), tmp);
- op1 = gen_rtx_ZERO_EXTEND (TImode, op1);
- op1 = gen_rtx_ASHIFT (TImode, op1, GEN_INT (64));
- op1 = gen_rtx_IOR (TImode, tmp, op1);
+ /* Use *insvti_lowpart_1 to set lowpart. */
+ if (SUBREG_BYTE (op0) == 0)
+ {
+ wide_int mask = wi::mask (64, true, 128);
+ rtx tmp = immed_wide_int_const (mask, TImode);
+ 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_rtx_ZERO_EXTEND (TImode, op1);
+ op1 = gen_rtx_IOR (TImode, tmp, op1);
+ }
+ /* Use *insvti_highpart_1 to set highpart. */
+ else if (SUBREG_BYTE (op0) == 8)
+ {
+ wide_int mask = wi::mask (64, false, 128);
+ rtx tmp = immed_wide_int_const (mask, TImode);
+ op0 = SUBREG_REG (op0);
+ tmp = gen_rtx_AND (TImode, copy_rtx (op0), tmp);
+ if (mode == DFmode)
+ op1 = force_reg (DImode, gen_lowpart (DImode, op1));
+
