[PR target/118357] RISC-V: Disable fusing vsetvl instructions by VSETVL_VTYPE_CHANGE_...

In RVV 1.0, the instruction "vsetvli	zero,zero,*" indicates that the
available vector length (avl) does not change. However, in XTheadVector,
this same instruction signifies that the avl should take the maximum value.
Consequently, when fusing vsetvl instructions, the optimization labeled
"VSETVL_VTYPE_CHANGE_ONLY" is disabled for XTheadVector.

	PR target/118357

gcc/ChangeLog:

	* config/riscv/riscv-vsetvl.cc: Function change_vtype_only_p always
	returns false for XTheadVector.

gcc/testsuite/ChangeLog:

	* gcc.target/riscv/rvv/xtheadvector/pr118357.c: New test.

diff --git a/gcc/config/riscv/riscv-vsetvl.cc b/gcc/config/riscv/riscv-vsetvl.cc
index a4016beebc0c1494074fc4a6c3a5137c84bac7d4..72c4c59514e5217f2e42d7b25eb0f57249395ea9 100644 (file)
--- a/gcc/config/riscv/riscv-vsetvl.cc
+++ b/gcc/config/riscv/riscv-vsetvl.cc
@@ -903,7 +903,8 @@ public:
   bool valid_p () const { return m_state == state_type::VALID; }
   bool unknown_p () const { return m_state == state_type::UNKNOWN; }
   bool empty_p () const { return m_state == state_type::EMPTY; }
-  bool change_vtype_only_p () const { return m_change_vtype_only; }
+  bool change_vtype_only_p () const { return m_change_vtype_only
+                                            && !TARGET_XTHEADVECTOR; }
 
   void set_valid () { m_state = state_type::VALID; }
   void set_unknown () { m_state = state_type::UNKNOWN; }

diff --git a/gcc/testsuite/gcc.target/riscv/rvv/xtheadvector/pr118357.c b/gcc/testsuite/gcc.target/riscv/rvv/xtheadvector/pr118357.c
new file mode 100644 (file)
index 0000000..aebb0e3
--- /dev/null
+++ b/gcc/testsuite/gcc.target/riscv/rvv/xtheadvector/pr118357.c
@@ -0,0 +1,13 @@
+/* { dg-do compile { target { rv64 } } } */
+/* { dg-options "-march=rv64gc_xtheadvector -mabi=lp64d -O2" } */
+
+#include <riscv_vector.h>
+
+vfloat16m4_t foo (float *ptr, size_t vl)
+{
+  vfloat32m8_t _p = __riscv_vle32_v_f32m8 (ptr, vl);
+  vfloat16m4_t _half = __riscv_vfncvt_f_f_w_f16m4 (_p, vl);
+  return _half;
+}
+
+/* { dg-final { scan-assembler-not {th.vsetvli\tzero,zero} } }*/