[PATCH V3] rs6000: Load high and low part of 64bit constant independently
Jiufu Guo
guojiufu@linux.ibm.com
Wed Jan 4 06:51:40 GMT 2023
Hi,
Compare with previous version, this patch updates the comments only.
https://gcc.gnu.org/pipermail/gcc-patches/2022-December/608293.html
For a complicate 64bit constant, below is one instruction-sequence to
build:
lis 9,0x800a
ori 9,9,0xabcd
sldi 9,9,32
oris 9,9,0xc167
ori 9,9,0xfa16
while we can also use below sequence to build:
lis 9,0xc167
lis 10,0x800a
ori 9,9,0xfa16
ori 10,10,0xabcd
rldimi 9,10,32,0
This sequence is using 2 registers to build high and low part firstly,
and then merge them.
In parallel aspect, this sequence would be faster. (Ofcause, using 1 more
register with potential register pressure).
The instruction sequence with two registers for parallel version can be
generated only if can_create_pseudo_p. Otherwise, the one register
sequence is generated.
Bootstrap and regtest pass on ppc64{,le}.
Is this ok for trunk?
BR,
Jeff(Jiufu)
gcc/ChangeLog:
* config/rs6000/rs6000.cc (rs6000_emit_set_long_const): Generate
more parallel code if can_create_pseudo_p.
gcc/testsuite/ChangeLog:
* gcc.target/powerpc/parall_5insn_const.c: New test.
---
gcc/config/rs6000/rs6000.cc | 39 +++++++++++++------
.../gcc.target/powerpc/parall_5insn_const.c | 27 +++++++++++++
2 files changed, 54 insertions(+), 12 deletions(-)
create mode 100644 gcc/testsuite/gcc.target/powerpc/parall_5insn_const.c
diff --git a/gcc/config/rs6000/rs6000.cc b/gcc/config/rs6000/rs6000.cc
index 6ac3adcec6b..b4f03499252 100644
--- a/gcc/config/rs6000/rs6000.cc
+++ b/gcc/config/rs6000/rs6000.cc
@@ -10366,19 +10366,34 @@ rs6000_emit_set_long_const (rtx dest, HOST_WIDE_INT c)
}
else
{
- temp = !can_create_pseudo_p () ? dest : gen_reg_rtx (DImode);
-
- emit_move_insn (temp, GEN_INT (sext_hwi (ud4 << 16, 32)));
- if (ud3 != 0)
- emit_move_insn (temp, gen_rtx_IOR (DImode, temp, GEN_INT (ud3)));
+ if (can_create_pseudo_p ())
+ {
+ /* lis HIGH,UD4 ; ori HIGH,UD3 ;
+ lis LOW,UD2 ; ori LOW,UD1 ; rldimi LOW,HIGH,32,0. */
+ rtx high = gen_reg_rtx (DImode);
+ rtx low = gen_reg_rtx (DImode);
+ HOST_WIDE_INT num = (ud2 << 16) | ud1;
+ rs6000_emit_set_long_const (low, sext_hwi (num, 32));
+ num = (ud4 << 16) | ud3;
+ rs6000_emit_set_long_const (high, sext_hwi (num, 32));
+ emit_insn (gen_rotldi3_insert_3 (dest, high, GEN_INT (32), low,
+ GEN_INT (0xffffffff)));
+ }
+ else
+ {
+ /* lis DEST,UD4 ; ori DEST,UD3 ; rotl DEST,32 ;
+ oris DEST,UD2 ; ori DEST,UD1. */
+ emit_move_insn (dest, GEN_INT (sext_hwi (ud4 << 16, 32)));
+ if (ud3 != 0)
+ emit_move_insn (dest, gen_rtx_IOR (DImode, dest, GEN_INT (ud3)));
- emit_move_insn (ud2 != 0 || ud1 != 0 ? temp : dest,
- gen_rtx_ASHIFT (DImode, temp, GEN_INT (32)));
- if (ud2 != 0)
- emit_move_insn (ud1 != 0 ? temp : dest,
- gen_rtx_IOR (DImode, temp, GEN_INT (ud2 << 16)));
- if (ud1 != 0)
- emit_move_insn (dest, gen_rtx_IOR (DImode, temp, GEN_INT (ud1)));
+ emit_move_insn (dest, gen_rtx_ASHIFT (DImode, dest, GEN_INT (32)));
+ if (ud2 != 0)
+ emit_move_insn (dest,
+ gen_rtx_IOR (DImode, dest, GEN_INT (ud2 << 16)));
+ if (ud1 != 0)
+ emit_move_insn (dest, gen_rtx_IOR (DImode, dest, GEN_INT (ud1)));
+ }
}
}
diff --git a/gcc/testsuite/gcc.target/powerpc/parall_5insn_const.c b/gcc/testsuite/gcc.target/powerpc/parall_5insn_const.c
new file mode 100644
index 00000000000..e3a9a7264cf
--- /dev/null
+++ b/gcc/testsuite/gcc.target/powerpc/parall_5insn_const.c
@@ -0,0 +1,27 @@
+/* { dg-do run } */
+/* { dg-options "-O2 -mno-prefixed -save-temps" } */
+/* { dg-require-effective-target has_arch_ppc64 } */
+
+/* { dg-final { scan-assembler-times {\mlis\M} 4 } } */
+/* { dg-final { scan-assembler-times {\mori\M} 4 } } */
+/* { dg-final { scan-assembler-times {\mrldimi\M} 2 } } */
+
+void __attribute__ ((noinline)) foo (unsigned long long *a)
+{
+ /* 2 lis + 2 ori + 1 rldimi for each constant. */
+ *a++ = 0x800aabcdc167fa16ULL;
+ *a++ = 0x7543a876867f616ULL;
+}
+
+long long A[] = {0x800aabcdc167fa16ULL, 0x7543a876867f616ULL};
+int
+main ()
+{
+ long long res[2];
+
+ foo (res);
+ if (__builtin_memcmp (res, A, sizeof (res)) != 0)
+ __builtin_abort ();
+
+ return 0;
+}
--
2.17.1
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