This is a revised version of the patch posted at
https://gcc.gnu.org/pipermail/gcc-patches/2020-March/542718.html, resend
this since this is a quite high priority performance issue for Power.
Don't split code from add<mode>3 for SDI to allow a later pass to split.
This allows later logic to hoist out constant load in add instructions.
In loop, lis+ori could be hoisted out to improve performance compared with
previous addis+addi (About 15% on typical case), weak point is
one more register is used and one more instruction is generated. i.e.:
addis 3,3,0x6765
addi 3,3,0x4321
=>
lis 9,0x6765
ori 9,9,0x4321
add 3,3,9
Likewise, paddi is replaced with pli+add for Power10. No obvious performance
and binary size change to SPEC2017.
gcc/ChangeLog:
2020-10-21 Xiong Hu Luo <luo...@linux.ibm.com>
* config/rs6000/rs6000.md (add<mode>3 for SDI): Don't split before
reload,
move constant to temp register for add.
gcc/testsuite/ChangeLog:
2020-10-21 Xiong Hu Luo <luo...@linux.ibm.com>
* gcc.target/powerpc/prefix-add.c: Check pli instead of paddi.
* gcc.target/powerpc/prefix-no-update.c: Likewise.
* gcc.target/powerpc/add-const.c: New test.
---
gcc/config/rs6000/predicates.md | 3 +-
gcc/config/rs6000/rs6000.md | 54 +++++++++++--------
gcc/testsuite/gcc.target/powerpc/add-const.c | 18 +++++++
gcc/testsuite/gcc.target/powerpc/prefix-add.c | 4 +-
.../gcc.target/powerpc/prefix-no-update.c | 2 +-
5 files changed, 54 insertions(+), 27 deletions(-)
create mode 100644 gcc/testsuite/gcc.target/powerpc/add-const.c
diff --git a/gcc/config/rs6000/predicates.md b/gcc/config/rs6000/predicates.md
index 4c2fe7fa312..af577da669e 100644
--- a/gcc/config/rs6000/predicates.md
+++ b/gcc/config/rs6000/predicates.md
@@ -859,8 +859,7 @@ (define_special_predicate "indexed_address_mem"
(define_predicate "add_operand"
(if_then_else (match_code "const_int")
(match_test "satisfies_constraint_I (op)
- || satisfies_constraint_L (op)
- || satisfies_constraint_eI (op)")
+ || satisfies_constraint_L (op)")
(match_operand 0 "gpc_reg_operand")))
;; Return 1 if the operand is either a non-special register, or 0, or -1.
diff --git a/gcc/config/rs6000/rs6000.md b/gcc/config/rs6000/rs6000.md
index 779bfd11237..facf6e12114 100644
--- a/gcc/config/rs6000/rs6000.md
+++ b/gcc/config/rs6000/rs6000.md
@@ -1750,34 +1750,44 @@ (define_expand "add<mode>3"
if (CONST_INT_P (operands[2]) && !add_operand (operands[2], <MODE>mode))
{
- rtx tmp = ((!can_create_pseudo_p ()
- || rtx_equal_p (operands[0], operands[1]))
- ? operands[0] : gen_reg_rtx (<MODE>mode));
+ bool reg0 = (reg_or_subregno (operands[0]) == 0);
+ if (can_create_pseudo_p () || reg0)
+ {
+
+ rtx tmp = (!can_create_pseudo_p ()
+ || rtx_equal_p (operands[0], operands[1]))
+ ? operands[0] : gen_reg_rtx (<MODE>mode);
/* Adding a constant to r0 is not a valid insn, so use a different
- strategy in that case. */
- if (reg_or_subregno (operands[1]) == 0 || reg_or_subregno (tmp) == 0)
- {
- if (operands[0] == operands[1])
- FAIL;
- rs6000_emit_move (operands[0], operands[2], <MODE>mode);
- emit_insn (gen_add<mode>3 (operands[0], operands[1], operands[0]));
+ strategy in that case. See stack-limit.c, need generate
+ "24: %0:DI=0x20fa0; 25: %0:DI=%14:DI+%0:DI" in pro_and_epilogue
+ when can_create_pseudo_p is false. */
+ if (reg0 == 0 || reg_or_subregno (tmp) == 0)
+ {
+ if (operands[0] == operands[1])
+ FAIL;
+ }
+
+ rs6000_emit_move (tmp, operands[2], <MODE>mode);
+ emit_insn (gen_add<mode>3 (operands[0], operands[1], tmp));
DONE;
}
+ else
+ {
+ HOST_WIDE_INT val = INTVAL (operands[2]);
+ HOST_WIDE_INT low = ((val & 0xffff) ^ 0x8000) - 0x8000;
+ HOST_WIDE_INT rest = trunc_int_for_mode (val - low, <MODE>mode);
- HOST_WIDE_INT val = INTVAL (operands[2]);
- HOST_WIDE_INT low = ((val & 0xffff) ^ 0x8000) - 0x8000;
- HOST_WIDE_INT rest = trunc_int_for_mode (val - low, <MODE>mode);
-
- if (<MODE>mode == DImode && !satisfies_constraint_L (GEN_INT (rest)))
- FAIL;
+ if (<MODE>mode == DImode && !satisfies_constraint_L (GEN_INT (rest)))
+ FAIL;
- /* The ordering here is important for the prolog expander.
- When space is allocated from the stack, adding 'low' first may
- produce a temporary deallocation (which would be bad). */
- emit_insn (gen_add<mode>3 (tmp, operands[1], GEN_INT (rest)));
- emit_insn (gen_add<mode>3 (operands[0], tmp, GEN_INT (low)));
- DONE;
+ /* The ordering here is important for the prolog expander.
+ When space is allocated from the stack, adding 'low' first may
+ produce a temporary deallocation (which would be bad). */
+ emit_insn (gen_add<mode>3 (operands[0], operands[1], GEN_INT (rest)));
+ emit_insn (gen_add<mode>3 (operands[0], operands[0], GEN_INT (low)));
+ DONE;
+ }
}
})
diff --git a/gcc/testsuite/gcc.target/powerpc/add-const.c
b/gcc/testsuite/gcc.target/powerpc/add-const.c
new file mode 100644
index 00000000000..eeeed091032
--- /dev/null
+++ b/gcc/testsuite/gcc.target/powerpc/add-const.c
@@ -0,0 +1,18 @@
+/* { dg-do compile { target { lp64 } } } */
+/* { dg-options "-O3 -fno-unroll-loops" } */
+
+/* Ensure the lis,ori are generated, which indicates they have
+ been hoisted outside of the loop. */
+
+typedef unsigned long ulong;
+ulong
+foo (ulong n, ulong h)
+{
+ int i;
+ for (i = 0; i < n; i++)
+ h = ((h + 8) | h) + 0x67654321;
+ return h;
+}
+
+/* { dg-final { scan-assembler-times {\mlis\M} 1 } } */
+/* { dg-final { scan-assembler-times {\mori\M} 1 } } */
diff --git a/gcc/testsuite/gcc.target/powerpc/prefix-add.c
b/gcc/testsuite/gcc.target/powerpc/prefix-add.c
index 0027406e457..13af39e51ec 100644
--- a/gcc/testsuite/gcc.target/powerpc/prefix-add.c
+++ b/gcc/testsuite/gcc.target/powerpc/prefix-add.c
@@ -2,13 +2,13 @@
/* { dg-require-effective-target powerpc_prefixed_addr } */
/* { dg-options "-O2 -mdejagnu-cpu=power10" } */
-/* Test that PADDI is generated to add a large constant. */
+/* Test that PLI is generated to add a large constant. */
unsigned long
add (unsigned long a)
{
return a + 0x12345U;
}
-/* { dg-final { scan-assembler {\mpaddi\M} } } */
+/* { dg-final { scan-assembler {\mpli\M} } } */
/* { dg-final { scan-assembler-not {\maddi\M} } } */
/* { dg-final { scan-assembler-not {\maddis\M} } } */
diff --git a/gcc/testsuite/gcc.target/powerpc/prefix-no-update.c
b/gcc/testsuite/gcc.target/powerpc/prefix-no-update.c
index 837fcd77c0b..26221d3eec5 100644
--- a/gcc/testsuite/gcc.target/powerpc/prefix-no-update.c
+++ b/gcc/testsuite/gcc.target/powerpc/prefix-no-update.c
@@ -42,7 +42,7 @@ struct foo *dec_store (struct foo *p, unsigned int *q)
/* { dg-final { scan-assembler-times {\mlwz\M} 2 } } */
/* { dg-final { scan-assembler-times {\mstw\M} 2 } } */
-/* { dg-final { scan-assembler-times {\mpaddi\M} 4 } } */
+/* { dg-final { scan-assembler-times {\mpli\M} 4 } } */
/* { dg-final { scan-assembler-times {\mplwz\M} 2 } } */
/* { dg-final { scan-assembler-times {\mpstw\M} 2 } } */
/* { dg-final { scan-assembler-not {\mplwzu\M} } } */
--
2.25.1
