When checking eq/neq with a constant which has only 16bits, then it can
be optimized to check the rotated data. By this, the constant building
is optimized.
As the example in PR103743:
For "in == 0x8000000000000000LL", this patch generates:
rotldi %r3,%r3,16
cmpldi %cr0,%r3,32768
instead:
li %r9,-1
rldicr %r9,%r9,0,0
cmpd %cr0,%r3,%r9
This patch pass bootstrap and regtest on ppc64 and ppc64le.
Ok for trunk? Thanks!
BR,
Jiufu
PR target/103743
gcc/ChangeLog:
* config/rs6000/rs6000.cc (rot_to_16bits): New function.
(rs6000_generate_compare): Compare rotated const for eq.
gcc/testsuite/ChangeLog:
* gcc.target/powerpc/pr103743.c: New test.
* gcc.target/powerpc/pr103743_1.c: New test.
---
gcc/config/rs6000/rs6000.cc | 62 +++++++++++++
gcc/testsuite/gcc.target/powerpc/pr103743.c | 48 ++++++++++
gcc/testsuite/gcc.target/powerpc/pr103743_1.c | 87 +++++++++++++++++++
3 files changed, 197 insertions(+)
create mode 100644 gcc/testsuite/gcc.target/powerpc/pr103743.c
create mode 100644 gcc/testsuite/gcc.target/powerpc/pr103743_1.c
diff --git a/gcc/config/rs6000/rs6000.cc b/gcc/config/rs6000/rs6000.cc
index 3afe78f5d04..4aa1d0ca4ab 100644
--- a/gcc/config/rs6000/rs6000.cc
+++ b/gcc/config/rs6000/rs6000.cc
@@ -14860,6 +14860,42 @@ rs6000_reverse_condition (machine_mode mode, enum
rtx_code code)
return reverse_condition (code);
}
+/* If SRC is a constant with only 16bits, return the number by which
+ the constant can be rotated to lowest 16bits.
+ Return 0, if SRC does not meet requirements.
+ Set *sgn to 1 if the rotated cst is negative, otherwise set it to 0.
+ Set *res_cst to the rotated constant. */
+
+static int
+rot_to_16bits (rtx src, machine_mode mode, bool *sgn, rtx *res_cst)
+{
+ if (!(src && CONST_INT_P (src)))
+ return 0;
+
+ unsigned HOST_WIDE_INT C = INTVAL (src);
+
+ /* If all 0 except low 16bits. */
+ int leadz = clz_hwi (C) + 16;
+ rtx cst = simplify_gen_binary (ROTATE, mode, src, GEN_INT (leadz));
+ if (satisfies_constraint_K (cst))
+ {
+ *res_cst = cst;
+ return leadz;
+ }
+
+ /* If all 1 except low 15bits. */
+ leadz = clz_hwi (~C) + 15;
+ cst = simplify_gen_binary (ROTATE, mode, src, GEN_INT (leadz));
+ if (satisfies_constraint_I (cst))
+ {
+ *sgn = true;
+ *res_cst = cst;
+ return leadz;
+ }
+
+ return 0;
+}
+
/* Generate a compare for CODE. Return a brand-new rtx that
represents the result of the compare. */
@@ -14889,6 +14925,32 @@ rs6000_generate_compare (rtx cmp, machine_mode mode)
else
comp_mode = CCmode;
+ /* "i == C" ==> "rotl(i,N) == rotl(C,N)" if rotl(C,N) only low 16bits. */
+ if ((code == NE || code == EQ) && mode == DImode)
+ {
+ /* The constant would already been set to a reg in the last insn. */
+ rtx_insn *last = get_last_insn_anywhere ();
+ rtx set = last ? single_set (last) : NULL_RTX;
+ rtx src = (set && SET_DEST (set) == op1) ? SET_SRC (set) : NULL_RTX;
+
+ /* It constant may be in constant pool. */
+ if (src && MEM_P (src))
+ src = avoid_constant_pool_reference (src);
+
+ rtx cst = NULL_RTX;
+ bool sgn = false;
+ int n = rot_to_16bits (src, mode, &sgn, &cst);
+ if (n >= 16 && n <= 48)
+ {
+ rtx dest = gen_reg_rtx (mode);
+ emit_insn (
+ gen_rtx_SET (dest, gen_rtx_ROTATE (mode, op0, GEN_INT (n))));
+ op0 = dest;
+ op1 = cst;
+ comp_mode = sgn ? CCmode : CCUNSmode;
+ }
+ }
+
/* If we have an unsigned compare, make sure we don't have a signed value as
an immediate. */
if (comp_mode == CCUNSmode && CONST_INT_P (op1)
diff --git a/gcc/testsuite/gcc.target/powerpc/pr103743.c
b/gcc/testsuite/gcc.target/powerpc/pr103743.c
new file mode 100644
index 00000000000..606e5e51c4f
--- /dev/null
+++ b/gcc/testsuite/gcc.target/powerpc/pr103743.c
@@ -0,0 +1,48 @@
+/* { dg-do compile } */
+/* { dg-require-effective-target lp64 } */
+/* { dg-options "-O2" } */
+/* { dg-final { scan-assembler-times "cmpldi" 8 } } */
+/* { dg-final { scan-assembler-times "cmpdi" 4 } } */
+/* { dg-final { scan-assembler-times "rotldi" 8 } } */
+
+int foo (int a);
+
+int __attribute__ ((noinline)) udi_fun (unsigned long long in)
+{
+ if (in == (0x8642000000000000ULL))
+ return foo (1);
+ if (in == (0x7642000000000000ULL))
+ return foo (12);
+ if (in == (0x8000000000000000ULL))
+ return foo (32);
+ if (in == (0x8642FFFFFFFFFFFFULL))
+ return foo (46);
+ if (in == (0x7642FFFFFFFFFFFFULL))
+ return foo (51);
+ if (in == (0x7567000000ULL))
+ return foo (9);
+ if (in == (0xFFF8567FFFFFFFFFULL))
+ return foo (19);
+
+ return 0;
+}
+
+int __attribute__ ((noinline)) di_fun (long long in)
+{
+ if (in == (0x8642000000000000LL))
+ return foo (1);
+ if (in == (0x7642000000000000LL))
+ return foo (12);
+ if (in == (0x8000000000000000LL))
+ return foo (32);
+ if (in == (0x8642FFFFFFFFFFFFLL))
+ return foo (46);
+ if (in == (0x7642FFFFFFFFFFFFLL))
+ return foo (51);
+ if (in == (0x7567000000LL))
+ return foo (9);
+ if (in == (0xFFF8567FFFFFFFFFLL))
+ return foo (19);
+
+ return 0;
+}
diff --git a/gcc/testsuite/gcc.target/powerpc/pr103743_1.c
b/gcc/testsuite/gcc.target/powerpc/pr103743_1.c
new file mode 100644
index 00000000000..56fbbe4d4f1
--- /dev/null
+++ b/gcc/testsuite/gcc.target/powerpc/pr103743_1.c
@@ -0,0 +1,87 @@
+/* { dg-do run } */
+/* { dg-options "-O2 -std=c99" } */
+
+int
+foo (int a)
+{
+ return a + 6;
+}
+
+int __attribute__ ((noinline)) udi_fun (unsigned long long in)
+{
+ if (in == (0x8642000000000000ULL))
+ return foo (1);
+ if (in == (0x7642000000000000ULL))
+ return foo (12);
+ if (in == (0x8000000000000000ULL))
+ return foo (32);
+ if (in == (0x8642FFFFFFFFFFFFULL))
+ return foo (46);
+ if (in == (0x7642FFFFFFFFFFFFULL))
+ return foo (51);
+ if (in == (0x7567000000ULL))
+ return foo (9);
+ if (in == (0xFFF8567FFFFFFFFFULL))
+ return foo (19);
+
+ return 0;
+}
+
+int __attribute__ ((noinline)) di_fun (long long in)
+{
+ if (in == (0x8642000000000000LL))
+ return foo (1);
+ if (in == (0x7642000000000000LL))
+ return foo (12);
+ if (in == (0x8000000000000000LL))
+ return foo (32);
+ if (in == (0x8642FFFFFFFFFFFFLL))
+ return foo (46);
+ if (in == (0x7642FFFFFFFFFFFFLL))
+ return foo (51);
+ return 0;
+}
+
+int
+main ()
+{
+ int e = 0;
+ if (udi_fun (6) != 0)
+ e++;
+ if (udi_fun (0x8642000000000000ULL) != foo (1))
+ e++;
+ if (udi_fun (0x7642000000000000ULL) != foo (12))
+ e++;
+ if (udi_fun (0x8000000000000000ULL) != foo (32))
+ e++;
+ if (udi_fun (0x8642FFFFFFFFFFFFULL) != foo (46))
+ e++;
+ if (udi_fun (0x7642FFFFFFFFFFFFULL) != foo (51))
+ e++;
+ if (udi_fun (0x7567000000ULL) != foo (9))
+ e++;
+ if (udi_fun (0xFFF8567FFFFFFFFFULL) != foo (19))
+ e++;
+
+ if (di_fun (6) != 0)
+ e++;
+ if (di_fun (0x8642000000000000LL) != foo (1))
+ e++;
+ if (di_fun (0x7642000000000000LL) != foo (12))
+ e++;
+ if (di_fun (0x8000000000000000LL) != foo (32))
+ e++;
+ if (di_fun (0x8642FFFFFFFFFFFFLL) != foo (46))
+ e++;
+ if (di_fun (0x7642FFFFFFFFFFFFLL) != foo (51))
+ e++;
+ if (udi_fun (0x7567000000LL) != foo (9))
+ e++;
+ if (udi_fun (0xFFF8567FFFFFFFFFLL) != foo (19))
+ e++;
+
+ if (e)
+ __builtin_abort ();
+ return 0;
+}
+
--
2.25.1
