Extend AdvSIMD constant materialization to recognize 128‑bit integer vector
constants where the low 64 bits contain a duplicated scalar value and the high
64 bits are zero.
Bootstrapped and tested on aarch64-linux-gnu.
PR target/113926
gcc/ChangeLog:
* config/aarch64/aarch64.cc (struct simd_immediate_info): Add width
field to record AdvSIMD output vector width.
(simd_immediate_info::simd_immediate_info): Initialize width to zero
in all constructors.
(aarch64_simd_valid_imm): Allow 128-bit AdvSIMD MOV immediates with
zero high 64 bits to be materialized using 64-bit MOVI.
(aarch64_output_simd_imm): Use recorded immediate width when outputting
AdvSIMD immediates.
gcc/testsuite/ChangeLog:
* gcc.target/aarch64/pr113926.c: New test.
Signed-off-by: Naveen <[email protected]>
---
gcc/config/aarch64/aarch64.cc | 52 +++++++++++++++++----
gcc/testsuite/gcc.target/aarch64/pr113926.c | 43 +++++++++++++++++
2 files changed, 86 insertions(+), 9 deletions(-)
create mode 100644 gcc/testsuite/gcc.target/aarch64/pr113926.c
diff --git a/gcc/config/aarch64/aarch64.cc b/gcc/config/aarch64/aarch64.cc
index 3816df92b18..033a868d15e 100644
--- a/gcc/config/aarch64/aarch64.cc
+++ b/gcc/config/aarch64/aarch64.cc
@@ -169,6 +169,9 @@ struct simd_immediate_info
/* The mode of the elements. */
scalar_mode elt_mode;
+ /* If nonzero, the vector width to print the AdvSIMD immediate. */
+ unsigned int width = 0;
+
/* The instruction to use to move the immediate into a vector. */
insn_type insn;
@@ -203,7 +206,7 @@ struct simd_immediate_info
ELT_MODE_IN and value VALUE_IN. */
inline simd_immediate_info
::simd_immediate_info (scalar_float_mode elt_mode_in, rtx value_in)
- : elt_mode (elt_mode_in), insn (MOV)
+ : elt_mode (elt_mode_in), width (0), insn (MOV)
{
u.mov.value = value_in;
u.mov.modifier = LSL;
@@ -218,7 +221,7 @@ inline simd_immediate_info
unsigned HOST_WIDE_INT value_in,
insn_type insn_in, modifier_type modifier_in,
unsigned int shift_in)
- : elt_mode (elt_mode_in), insn (insn_in)
+ : elt_mode (elt_mode_in), width (0), insn (insn_in)
{
u.mov.value = gen_int_mode (value_in, elt_mode_in);
u.mov.modifier = modifier_in;
@@ -229,7 +232,7 @@ inline simd_immediate_info
and where element I is equal to BASE_IN + I * STEP_IN. */
inline simd_immediate_info
::simd_immediate_info (scalar_mode elt_mode_in, rtx base_in, rtx step_in)
- : elt_mode (elt_mode_in), insn (INDEX)
+ : elt_mode (elt_mode_in), width (0), insn (INDEX)
{
u.index.base = base_in;
u.index.step = step_in;
@@ -240,7 +243,7 @@ inline simd_immediate_info
inline simd_immediate_info
::simd_immediate_info (scalar_int_mode elt_mode_in,
aarch64_svpattern pattern_in)
- : elt_mode (elt_mode_in), insn (PTRUE)
+ : elt_mode (elt_mode_in), width (0), insn (PTRUE)
{
u.pattern = pattern_in;
}
@@ -24491,12 +24494,35 @@ aarch64_simd_valid_imm (rtx op, simd_immediate_info
*info,
}
}
- /* The immediate must repeat every eight bytes. */
- unsigned int nbytes = bytes.length ();
- for (unsigned i = 8; i < nbytes; ++i)
- if (bytes[i] != bytes[i - 8])
+/* The immediate must normally repeat every eight bytes. For MOV
+ also allow a 128-bit AdvSIMD constant whose high 64 bits are zero
+ since it can be materialized using a 64-bit MOVI. */
+unsigned int nbytes = bytes.length ();
+unsigned int output_width = 0;
+bool repeats_every_8_bytes = true;
+
+for (unsigned int i = 8; i < nbytes; ++i)
+ if (bytes[i] != bytes[i - 8])
+ {
+ repeats_every_8_bytes = false;
+ break;
+ }
+
+if (!repeats_every_8_bytes)
+ {
+ if (which != AARCH64_CHECK_MOV
+ || !(vec_flags & VEC_ADVSIMD)
+ || aarch64_sve_mode_p (mode)
+ || nbytes != 16)
return false;
+ for (unsigned int i = 8; i < nbytes; ++i)
+ if (bytes[i] != 0)
+ return false;
+
+ output_width = 64;
+ }
+
/* Get the repeating 8-byte value as an integer. No endian correction
is needed here because bytes is already in lsb-first order. */
unsigned HOST_WIDE_INT val64 = 0;
@@ -24548,6 +24574,7 @@ aarch64_simd_valid_imm (rtx op, simd_immediate_info
*info,
{
rtx float_val = const_double_from_real_value (r, fmode);
*info = simd_immediate_info (fmode, float_val);
+ info->width = output_width;
}
return true;
}
@@ -24557,7 +24584,11 @@ aarch64_simd_valid_imm (rtx op, simd_immediate_info
*info,
return aarch64_sve_valid_immediate (ival, imode, info, which);
if (aarch64_advsimd_valid_immediate (val64, imode, info, which))
- return true;
+ {
+ if (info)
+ info->width = output_width;
+ return true;
+ }
if (TARGET_SVE)
return aarch64_sve_valid_immediate (ival, imode, info, which);
@@ -26925,6 +26956,9 @@ aarch64_output_simd_imm (rtx const_vector, unsigned
width,
is_valid = aarch64_simd_valid_imm (const_vector, &info, which);
gcc_assert (is_valid);
+ if (info.width != 0)
+ width = info.width;
+
element_char = sizetochar (GET_MODE_BITSIZE (info.elt_mode));
lane_count = width / GET_MODE_BITSIZE (info.elt_mode);
diff --git a/gcc/testsuite/gcc.target/aarch64/pr113926.c
b/gcc/testsuite/gcc.target/aarch64/pr113926.c
new file mode 100644
index 00000000000..e6e07087e87
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/pr113926.c
@@ -0,0 +1,43 @@
+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+
+/* Test recognition of 128-bit integer SIMD constants where the low 64 bits
+ contain a duplicated scalar value and the high 64 bits are all zero.
+ Such constants should be materialized using a single MOVI instruction.
+ PR113926. */
+
+typedef signed char v16qi __attribute__((vector_size(16)));
+typedef short v8hi __attribute__((vector_size(16)));
+typedef int v4si __attribute__((vector_size(16)));
+
+/* QI mode: low 64 bits duplicated, high 64 bits zero. */
+v16qi
+f_qi (void)
+{
+ return (v16qi)
+ { 3, 3, 3, 3, 3, 3, 3, 3,
+ 0, 0, 0, 0, 0, 0, 0, 0 };
+}
+
+/* HI mode: low 64 bits duplicated, high 64 bits zero. */
+v8hi
+f_hi (void)
+{
+ return (v8hi)
+ { 2, 2, 2, 2,
+ 0, 0, 0, 0 };
+}
+
+/* SI mode: low 64 bits duplicated, high 64 bits zero. */
+v4si
+f_si (void)
+{
+ return (v4si)
+ { 1, 1, 0, 0 };
+}
+
+/* Each function should generate exactly one MOVI instruction. */
+/* { dg-final { scan-assembler-times {\tmovi\tv[0-9]+\.8b, 0x3} 1 } } */
+/* { dg-final { scan-assembler-times {\tmovi\tv[0-9]+\.4h, 0x2} 1 } } */
+/* { dg-final { scan-assembler-times {\tmovi\tv[0-9]+\.2s, 0x1} 1 } } */
+/* { dg-final { scan-assembler-not {\tldr\tq[0-9]+,} } } */
--
2.34.1
