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From: "Roger Sayle" <>
To: <>
Cc: "'Uros Bizjak'" <>
Subject: [x86_64 PATCH] Two minor tweaks to ix86_expand_move.
Date: Fri, 16 Jun 2023 17:27:17 +0100	[thread overview]
Message-ID: <033d01d9a06f$6bdf2360$439d6a20$> (raw)

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This patch splits out two (independent) minor changes to'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

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

with this patch we now generate with -O2 (the same as V1TImode):

foo2:   movq    %rdi, %xmm0
        movq    %rsi, %xmm1
        punpcklqdq      %xmm1, %xmm0

and with -O2 -msse4 the even better:

foo2:   movq    %rdi, %xmm0
        pinsrq  $1, %rsi, %xmm0

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  <>

        * config/i386/ (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.

        * New test case.

Thanks in advance,

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diff --git a/gcc/config/i386/ b/gcc/config/i386/
index def060a..6a28b67 100644
--- a/gcc/config/i386/
+++ b/gcc/config/i386/
@@ -521,7 +521,8 @@ ix86_expand_move (machine_mode mode, rtx operands[])
-	  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[])
-  /* 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));
diff --git a/gcc/testsuite/ b/gcc/testsuite/
new file mode 100644
index 0000000..7e89085
--- /dev/null
+++ b/gcc/testsuite/
@@ -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" } } */

             reply	other threads:[~2023-06-16 16:27 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-06-16 16:27 Roger Sayle [this message]
2023-06-17 13:15 ` Uros Bizjak

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