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* [gcc r13-1943] Support logical shifts by (some) integer constants in TImode STV on x86_64.
@ 2022-08-03 8:01 Roger Sayle
0 siblings, 0 replies; only message in thread
From: Roger Sayle @ 2022-08-03 8:01 UTC (permalink / raw)
To: gcc-cvs
https://gcc.gnu.org/g:7baed397dd0c220a72589c435e7db1676aced01e
commit r13-1943-g7baed397dd0c220a72589c435e7db1676aced01e
Author: Roger Sayle <roger@nextmovesoftware.com>
Date: Wed Aug 3 09:00:20 2022 +0100
Support logical shifts by (some) integer constants in TImode STV on x86_64.
This patch improves TImode STV by adding support for logical shifts by
integer constants that are multiples of 8. For the test case:
unsigned __int128 a, b;
void foo() { a = b << 16; }
on x86_64, gcc -O2 currently generates:
movq b(%rip), %rax
movq b+8(%rip), %rdx
shldq $16, %rax, %rdx
salq $16, %rax
movq %rax, a(%rip)
movq %rdx, a+8(%rip)
ret
with this patch we now generate:
movdqa b(%rip), %xmm0
pslldq $2, %xmm0
movaps %xmm0, a(%rip)
ret
2022-08-03 Roger Sayle <roger@nextmovesoftware.com>
gcc/ChangeLog
* config/i386/i386-features.cc (compute_convert_gain): Add gain
for converting suitable TImode shift to a V1TImode shift.
(timode_scalar_chain::convert_insn): Add support for converting
suitable ASHIFT and LSHIFTRT.
(timode_scalar_to_vector_candidate_p): Consider logical shifts
by integer constants that are multiples of 8 to be candidates.
gcc/testsuite/ChangeLog
* gcc.target/i386/sse4_1-stv-7.c: New test case.
Diff:
---
gcc/config/i386/i386-features.cc | 21 +++++++++++++++++++++
gcc/testsuite/gcc.target/i386/sse4_1-stv-7.c | 18 ++++++++++++++++++
2 files changed, 39 insertions(+)
diff --git a/gcc/config/i386/i386-features.cc b/gcc/config/i386/i386-features.cc
index e3ecc22580a..5e3a7ffacb4 100644
--- a/gcc/config/i386/i386-features.cc
+++ b/gcc/config/i386/i386-features.cc
@@ -1221,6 +1221,13 @@ timode_scalar_chain::compute_convert_gain ()
igain = COSTS_N_INSNS (1);
break;
+ case ASHIFT:
+ case LSHIFTRT:
+ /* For logical shifts by constant multiples of 8. */
+ igain = optimize_insn_for_size_p () ? COSTS_N_BYTES (4)
+ : COSTS_N_INSNS (1);
+ break;
+
default:
break;
}
@@ -1469,6 +1476,12 @@ timode_scalar_chain::convert_insn (rtx_insn *insn)
src = convert_compare (XEXP (src, 0), XEXP (src, 1), insn);
break;
+ case ASHIFT:
+ case LSHIFTRT:
+ convert_op (&XEXP (src, 0), insn);
+ PUT_MODE (src, V1TImode);
+ break;
+
default:
gcc_unreachable ();
}
@@ -1803,6 +1816,14 @@ timode_scalar_to_vector_candidate_p (rtx_insn *insn)
case NOT:
return REG_P (XEXP (src, 0)) || timode_mem_p (XEXP (src, 0));
+ case ASHIFT:
+ case LSHIFTRT:
+ /* Handle logical shifts by integer constants between 0 and 120
+ that are multiples of 8. */
+ return REG_P (XEXP (src, 0))
+ && CONST_INT_P (XEXP (src, 1))
+ && (INTVAL (XEXP (src, 1)) & ~0x78) == 0;
+
default:
return false;
}
diff --git a/gcc/testsuite/gcc.target/i386/sse4_1-stv-7.c b/gcc/testsuite/gcc.target/i386/sse4_1-stv-7.c
new file mode 100644
index 00000000000..b0d5fceb29f
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/sse4_1-stv-7.c
@@ -0,0 +1,18 @@
+/* { dg-do compile { target int128 } } */
+/* { dg-options "-O2 -msse4.1 -mstv -mno-stackrealign" } */
+
+unsigned __int128 a;
+unsigned __int128 b;
+
+void foo()
+{
+ a = b << 16;
+}
+
+void bar()
+{
+ a = b >> 16;
+}
+
+/* { dg-final { scan-assembler "pslldq" } } */
+/* { dg-final { scan-assembler "psrldq" } } */
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2022-08-03 8:01 [gcc r13-1943] Support logical shifts by (some) integer constants in TImode STV on x86_64 Roger Sayle
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