[PATCH v2] RISC-V: Allow RVV VMS{Compare}(V1, V1) simplify to VMSET

[pan2.li@intel.com]

From: Pan Li <pan2.li@intel.com>

When some RVV integer compare operators act on the same vector registers
without mask. They can be simplified to VMSET.

This PATCH allow the eq, le, leu, ge, geu to perform such kind of the
simplification by adding vector bool support in relational_result of
the simplify rtx.

Given we have:
vbool1_t test_shortcut_for_riscv_vmseq_case_0(vint8m8_t v1, size_t vl)
{
  return __riscv_vmseq_vv_i8m8_b1(v1, v1, vl);
}

Before this patch:
vsetvli  zero,a2,e8,m8,ta,ma
vl8re8.v v8,0(a1)
vmseq.vv v8,v8,v8
vsetvli  a5,zero,e8,m8,ta,ma
vsm.v    v8,0(a0)
ret

After this patch:
vsetvli zero,a2,e8,m8,ta,ma
vmset.m v1                  <- optimized to vmset.m
vsetvli a5,zero,e8,m8,ta,ma
vsm.v   v1,0(a0)
ret

As above, we may have one instruction eliminated and require less vector
registers.

gcc/ChangeLog:

	* machmode.h (VECTOR_BOOL_MODE_P): Add new predication macro.
	* simplify-rtx.cc (relational_result): Add vector bool support.

gcc/testsuite/ChangeLog:

	* gcc.target/riscv/rvv/base/integer_compare_insn_shortcut.c:
	  Adjust test check condition.

Signed-off-by: Pan Li <pan2.li@intel.com>
---
 gcc/machmode.h                                              | 4 ++++
 gcc/simplify-rtx.cc                                         | 4 ++++
 .../riscv/rvv/base/integer_compare_insn_shortcut.c          | 6 +-----
 3 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/gcc/machmode.h b/gcc/machmode.h
index f1865c1ef42..5fbece0042f 100644
--- a/gcc/machmode.h
+++ b/gcc/machmode.h
@@ -134,6 +134,10 @@ extern const unsigned char mode_class[NUM_MACHINE_MODES];
    || GET_MODE_CLASS (MODE) == MODE_VECTOR_ACCUM	\
    || GET_MODE_CLASS (MODE) == MODE_VECTOR_UACCUM)
 
+/* Nonzero if MODE is a vector bool mode.  */
+#define VECTOR_BOOL_MODE_P(MODE)			\
+  (GET_MODE_CLASS (MODE) == MODE_VECTOR_BOOL)
+
 /* Nonzero if MODE is a scalar integral mode.  */
 #define SCALAR_INT_MODE_P(MODE)			\
   (GET_MODE_CLASS (MODE) == MODE_INT		\
diff --git a/gcc/simplify-rtx.cc b/gcc/simplify-rtx.cc
index d4aeebc7a5f..12aba4c4b05 100644
--- a/gcc/simplify-rtx.cc
+++ b/gcc/simplify-rtx.cc
@@ -2535,6 +2535,10 @@ relational_result (machine_mode mode, machine_mode cmp_mode, rtx res)
     {
       if (res == const0_rtx)
 	return CONST0_RTX (mode);
+
+      if (VECTOR_BOOL_MODE_P (mode) && res == const1_rtx)
+	return CONSTM1_RTX (mode);
+
 #ifdef VECTOR_STORE_FLAG_VALUE
       rtx val = VECTOR_STORE_FLAG_VALUE (mode);
       if (val == NULL_RTX)
diff --git a/gcc/testsuite/gcc.target/riscv/rvv/base/integer_compare_insn_shortcut.c b/gcc/testsuite/gcc.target/riscv/rvv/base/integer_compare_insn_shortcut.c
index 8954adad09d..1bca8467a16 100644
--- a/gcc/testsuite/gcc.target/riscv/rvv/base/integer_compare_insn_shortcut.c
+++ b/gcc/testsuite/gcc.target/riscv/rvv/base/integer_compare_insn_shortcut.c
@@ -283,9 +283,5 @@ vbool64_t test_shortcut_for_riscv_vmsgeu_case_6(vuint8mf8_t v1, size_t vl) {
   return __riscv_vmsgeu_vv_u8mf8_b64(v1, v1, vl);
 }
 
-/* { dg-final { scan-assembler-times {vmseq\.vv\sv[0-9],\s*v[0-9],\s*v[0-9]} 7 } } */
-/* { dg-final { scan-assembler-times {vmsle\.vv\sv[0-9],\s*v[0-9],\s*v[0-9]} 7 } } */
-/* { dg-final { scan-assembler-times {vmsleu\.vv\sv[0-9],\s*v[0-9],\s*v[0-9]} 7 } } */
-/* { dg-final { scan-assembler-times {vmsge\.vv\sv[0-9],\s*v[0-9],\s*v[0-9]} 7 } } */
-/* { dg-final { scan-assembler-times {vmsgeu\.vv\sv[0-9],\s*v[0-9],\s*v[0-9]} 7 } } */
 /* { dg-final { scan-assembler-times {vmclr\.m\sv[0-9]} 35 } } */
+/* { dg-final { scan-assembler-times {vmset\.m\sv[0-9]} 35 } } */
-- 
2.34.1