This patch splits out two (independent) minor changes to i386-expand.cc's
ix86_expand_move from a larger patch, given that it's better to review
and commit these independent pieces separately from a more complex patch.
The first change is to test for CONST_WIDE_INT_P before calling
ix86_convert_const_wide_int_to_broadcast. Whilst stepping through
this function in gdb, I was surprised that the code was continually
jumping into this function with operands that obviously weren't
appropriate.
The second change is to generalize the optimization for efficiently
moving a TImode value to V1TImode (via V2DImode), to cover all 128-bit
vector modes.
Hence for the test case:
typedef unsigned long uv2di __attribute__ ((__vector_size__ (16)));
uv2di foo2(__int128 x) { return (uv2di)x; }
we'd previously move via memory with:
foo2: movq %rdi, -24(%rsp)
movq %rsi, -16(%rsp)
movdqa -24(%rsp), %xmm0
ret
with this patch we now generate with -O2 (the same as V1TImode):
foo2: movq %rdi, %xmm0
movq %rsi, %xmm1
punpcklqdq %xmm1, %xmm0
ret
and with -O2 -msse4 the even better:
foo2: movq %rdi, %xmm0
pinsrq $1, %rsi, %xmm0
ret
The new test case is unimaginatively called sse2-v1ti-mov-2.c given
the original test case just for V1TI mode was called sse2-v1ti-mov-1.c.
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?
2023-06-16 Roger Sayle <ro...@nextmovesoftware.com>
gcc/ChangeLog
* config/i386/i386-expand.cc (ix86_expand_move): Check that OP1 is
CONST_WIDE_INT_P before calling ix86_convert_wide_int_to_broadcast.
Generalize special case for converting TImode to V1TImode to handle
all 128-bit vector conversions.
gcc/testsuite/ChangeLog
* gcc.target/i386/sse2-v1ti-mov-2.c: New test case.
Thanks in advance,
Roger
--
diff --git a/gcc/config/i386/i386-expand.cc b/gcc/config/i386/i386-expand.cc
index def060a..6a28b67 100644
--- a/gcc/config/i386/i386-expand.cc
+++ b/gcc/config/i386/i386-expand.cc
@@ -521,7 +521,8 @@ ix86_expand_move (machine_mode mode, rtx operands[])
return;
}
}
- else if (GET_MODE_SIZE (mode) >= 16)
+ else if (CONST_WIDE_INT_P (op1)
+ && GET_MODE_SIZE (mode) >= 16)
{
rtx tmp = ix86_convert_const_wide_int_to_broadcast
(GET_MODE (op0), op1);
@@ -696,8 +697,9 @@ ix86_expand_vector_move (machine_mode mode, rtx operands[])
return;
}
- /* Special case TImode to V1TImode conversions, via V2DI. */
- if (mode == V1TImode
+ /* Special case TImode to 128-bit vector conversions via V2DI. */
+ if (VECTOR_MODE_P (mode)
+ && GET_MODE_SIZE (mode) == 16
&& SUBREG_P (op1)
&& GET_MODE (SUBREG_REG (op1)) == TImode
&& TARGET_64BIT && TARGET_SSE
@@ -709,7 +711,7 @@ ix86_expand_vector_move (machine_mode mode, rtx operands[])
emit_move_insn (lo, gen_lowpart (DImode, SUBREG_REG (op1)));
emit_move_insn (hi, gen_highpart (DImode, SUBREG_REG (op1)));
emit_insn (gen_vec_concatv2di (tmp, lo, hi));
- emit_move_insn (op0, gen_lowpart (V1TImode, tmp));
+ emit_move_insn (op0, gen_lowpart (mode, tmp));
return;
}
diff --git a/gcc/testsuite/gcc.target/i386/sse2-v1ti-mov-2.c
b/gcc/testsuite/gcc.target/i386/sse2-v1ti-mov-2.c
new file mode 100644
index 0000000..7e89085
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/sse2-v1ti-mov-2.c
@@ -0,0 +1,16 @@
+/* { dg-do compile { target int128 } } */
+/* { dg-options "-O2 -msse2" } */
+
+typedef unsigned __int128 uv1ti __attribute__ ((__vector_size__ (16)));
+typedef unsigned long uv2di __attribute__ ((__vector_size__ (16)));
+typedef unsigned int uv4si __attribute__ ((__vector_size__ (16)));
+typedef unsigned short uv8hi __attribute__ ((__vector_size__ (16)));
+typedef unsigned char uv16qi __attribute__ ((__vector_size__ (16)));
+
+uv1ti foo1(__int128 x) { return (uv1ti)x; }
+uv2di foo2(__int128 x) { return (uv2di)x; }
+uv4si foo4(__int128 x) { return (uv4si)x; }
+uv8hi foo8(__int128 x) { return (uv8hi)x; }
+uv16qi foo16(__int128 x) { return (uv16qi)x; }
+
+/* { dg-final { scan-assembler-not "%\[er\]sp" } } */
