RISC-V: Optimize fault only first load

V2 patch for: https://patchwork.sourceware.org/project/gcc/patch/20230330012804.110539-1-juzhe.zhong@rivai.ai/
which has been reviewed.

This patch address Jeff's comment, refine ChangeLog to give more
clear information.

gcc/ChangeLog:

	* config/riscv/vector-iterators.md: New unspec to refine fault first load pattern.
	* config/riscv/vector.md: Refine fault first load pattern to erase avl from instructions
	with the fault first load property.

gcc/testsuite/ChangeLog:

	* gcc.target/riscv/rvv/vsetvl/ffload-1.c: New test.
	* gcc.target/riscv/rvv/vsetvl/ffload-2.c: New test.
	* gcc.target/riscv/rvv/vsetvl/ffload-3.c: New test.
	* gcc.target/riscv/rvv/vsetvl/ffload-5.c: New test.
	* gcc.target/riscv/rvv/vsetvl/ffload-6.c: New test.
	* gcc.target/riscv/rvv/vsetvl/ffload-7.c: New test.

8 files changed, 177 insertions, 1 deletions

diff --git a/gcc/config/riscv/vector-iterators.md b/gcc/config/riscv/vector-iterators.md
index 3c65752..a8e8561 100644
--- a/gcc/config/riscv/vector-iterators.md
+++ b/gcc/config/riscv/vector-iterators.md
@@ -80,6 +80,7 @@
   UNSPEC_VRGATHEREI16
   UNSPEC_VCOMPRESS
   UNSPEC_VLEFF
+  UNSPEC_MODIFY_VL
 ])
 
 (define_mode_iterator V [
diff --git a/gcc/config/riscv/vector.md b/gcc/config/riscv/vector.md
index 0fda11e..2c6d4fd 100644
--- a/gcc/config/riscv/vector.md
+++ b/gcc/config/riscv/vector.md
@@ -7414,7 +7414,15 @@
 	  (unspec:V
 	    [(match_operand:V 3 "memory_operand"         "    m,     m,     m,     m")] UNSPEC_VLEFF)
 	  (match_operand:V 2 "vector_merge_operand"      "   vu,     0,    vu,     0")))
-   (set (reg:SI VL_REGNUM) (unspec:SI [(match_dup 0)] UNSPEC_VLEFF))]
+   (set (reg:SI VL_REGNUM)
+	  (unspec:SI
+	    [(if_then_else:V
+	       (unspec:<VM>
+		[(match_dup 1) (match_dup 4) (match_dup 5)
+		 (match_dup 6) (match_dup 7)
+		 (reg:SI VL_REGNUM) (reg:SI VTYPE_REGNUM)] UNSPEC_VPREDICATE)
+	       (unspec:V [(match_dup 3)] UNSPEC_VLEFF)
+	       (match_dup 2))] UNSPEC_MODIFY_VL))]
   "TARGET_VECTOR"
   "vle<sew>ff.v\t%0,%3%p1"
   [(set_attr "type" "vldff")
diff --git a/gcc/testsuite/gcc.target/riscv/rvv/vsetvl/ffload-1.c b/gcc/testsuite/gcc.target/riscv/rvv/vsetvl/ffload-1.c
new file mode 100644
index 0000000..b2b7eaf
--- /dev/null
+++ b/gcc/testsuite/gcc.target/riscv/rvv/vsetvl/ffload-1.c
@@ -0,0 +1,21 @@
+/* { dg-do compile } */
+/* { dg-options "-march=rv32gcv -mabi=ilp32 -fno-tree-vectorize -fno-schedule-insns -fno-schedule-insns2" } */
+
+#include "riscv_vector.h"
+
+void f (int8_t * restrict in, int8_t * restrict out, int n, int cond,size_t *new_vl,size_t *new_vl2)
+{
+  size_t vl = 101;
+  
+  vint8mf8_t v = __riscv_vle8_v_i8mf8 (in, vl);
+  __riscv_vse8_v_i8mf8 (out, v, vl);
+  vbool64_t mask = __riscv_vlm_v_b64 (in + 100, vl);
+  vint8mf8_t v2 = __riscv_vle8ff_v_i8mf8_tumu (mask, v, in + 100, new_vl, vl);
+  __riscv_vse8_v_i8mf8 (out + 100, v2, *new_vl);
+  v2 = __riscv_vle8ff_v_i8mf8_tumu (mask, v2, in + 200, new_vl2, vl);
+  __riscv_vse8_v_i8mf8 (out + 200, v2, *new_vl2);
+}
+
+/* { dg-final { scan-assembler-times {vsetvli\s+zero,\s*[a-x0-9]+,\s*e8,\s*mf8,\s*tu,\s*mu} 2 { target { no-opts "-O0" no-opts "-g" no-opts "-funroll-loops" } } } } */
+/* { dg-final { scan-assembler-times {csrr} 2 { target { no-opts "-O0" no-opts "-g" no-opts "-funroll-loops" } } } } */
+/* { dg-final { scan-assembler-not {vmv} { target { no-opts "-O0" no-opts "-g" no-opts "-funroll-loops" } } } } */
diff --git a/gcc/testsuite/gcc.target/riscv/rvv/vsetvl/ffload-2.c b/gcc/testsuite/gcc.target/riscv/rvv/vsetvl/ffload-2.c
new file mode 100644
index 0000000..c0e21d4
--- /dev/null
+++ b/gcc/testsuite/gcc.target/riscv/rvv/vsetvl/ffload-2.c
@@ -0,0 +1,28 @@
+/* { dg-do compile } */
+/* { dg-options "-march=rv32gcv -mabi=ilp32 -fno-tree-vectorize -fno-schedule-insns -fno-schedule-insns2" } */
+
+#include "riscv_vector.h"
+
+void f (int8_t * restrict in, int8_t * restrict out, int n, int m, int cond)
+{
+  size_t vl = 101;
+  
+  for (size_t i = 0; i < n; i++)
+    {
+      vint8mf8_t v = __riscv_vle8_v_i8mf8 (in + i, vl);
+      __riscv_vse8_v_i8mf8 (out + i, v, vl);
+      
+      vbool64_t mask = __riscv_vlm_v_b64 (in + i + 100, vl);
+      
+      vint8mf8_t v2 = __riscv_vle8ff_v_i8mf8_tumu (mask, v, in + i + 100, &vl, vl);
+      __riscv_vse8_v_i8mf8 (out + i + 100, v2, vl);
+    }
+
+  for (size_t i = 0; i < n; i++)
+    {
+      vint8mf8_t v = __riscv_vle8_v_i8mf8 (in + i + 300, vl);
+      __riscv_vse8_v_i8mf8 (out + i + 300, v, vl);
+    }
+}
+
+/* { dg-final { scan-assembler-times {vsetvli\s+zero,\s*[a-x0-9]+,\s*e8,\s*mf8,\s*tu,\s*mu} 1 { target { no-opts "-O0" no-opts "-g" no-opts "-funroll-loops" } } } } */
diff --git a/gcc/testsuite/gcc.target/riscv/rvv/vsetvl/ffload-3.c b/gcc/testsuite/gcc.target/riscv/rvv/vsetvl/ffload-3.c
new file mode 100644
index 0000000..9e90b18
--- /dev/null
+++ b/gcc/testsuite/gcc.target/riscv/rvv/vsetvl/ffload-3.c
@@ -0,0 +1,28 @@
+/* { dg-do compile } */
+/* { dg-options "-march=rv32gcv -mabi=ilp32 -fno-tree-vectorize -fno-schedule-insns -fno-schedule-insns2" } */
+
+#include "riscv_vector.h"
+
+void f (int8_t * restrict in, int8_t * restrict out, int n, int m, int cond)
+{
+  size_t vl = 101;
+  
+  for (size_t i = 0; i < n; i++)
+    {
+      vint8mf8_t v = __riscv_vle8_v_i8mf8 (in + i, vl);
+      __riscv_vse8_v_i8mf8 (out + i, v, vl);
+      
+      vbool64_t mask = __riscv_vlm_v_b64 (in + i + 100, vl);
+      
+      vint8mf8_t v2 = __riscv_vle8ff_v_i8mf8_tumu (mask, v, in + i + 100, &vl, vl);
+      __riscv_vse8_v_i8mf8 (out + i + 100, v2, vl);
+    }
+
+  for (size_t i = 0; i < m; i++)
+    {
+      vint8mf8_t v = __riscv_vle8_v_i8mf8 (in + i + 300, vl);
+      __riscv_vse8_v_i8mf8 (out + i + 300, v, vl);
+    }
+}
+
+/* { dg-final { scan-assembler-times {vsetvli\s+zero,\s*[a-x0-9]+,\s*e8,\s*mf8,\s*t[au],\s*m[au]} 2 { target { no-opts "-O0" no-opts "-g" no-opts "-funroll-loops" } } } } */
diff --git a/gcc/testsuite/gcc.target/riscv/rvv/vsetvl/ffload-5.c b/gcc/testsuite/gcc.target/riscv/rvv/vsetvl/ffload-5.c
new file mode 100644
index 0000000..895180c
--- /dev/null
+++ b/gcc/testsuite/gcc.target/riscv/rvv/vsetvl/ffload-5.c
@@ -0,0 +1,29 @@
+/* { dg-do compile } */
+/* { dg-options "-march=rv32gcv -mabi=ilp32 -fno-tree-vectorize -fno-schedule-insns -fno-schedule-insns2" } */
+
+#include "riscv_vector.h"
+
+void f (int8_t * restrict in, int8_t * restrict out, int n, int m, int cond)
+{
+  size_t vl = 101;
+  size_t new_vl;
+  
+  for (size_t i = 0; i < n; i++)
+    {
+      vint8mf8_t v = __riscv_vle8_v_i8mf8 (in + i, vl);
+      __riscv_vse8_v_i8mf8 (out + i, v, vl);
+      
+      vbool64_t mask = __riscv_vlm_v_b64 (in + i + 100, vl);
+      
+      vint8mf8_t v2 = __riscv_vle8ff_v_i8mf8_tumu (mask, v, in + i + 100, &new_vl, vl);
+      __riscv_vse8_v_i8mf8 (out + i + 100, v2, new_vl);
+    }
+
+  for (size_t i = 0; i < n; i++)
+    {
+      vint8mf8_t v = __riscv_vle8_v_i8mf8 (in + i + 300, new_vl);
+      __riscv_vse8_v_i8mf8 (out + i + 300, v, new_vl);
+    }
+}
+
+/* { dg-final { scan-assembler-times {vsetvli\s+zero,\s*[a-x0-9]+,\s*e8,\s*mf8,\s*tu,\s*mu} 1 { target { no-opts "-O0" no-opts "-g" no-opts "-funroll-loops" } } } } */
diff --git a/gcc/testsuite/gcc.target/riscv/rvv/vsetvl/ffload-6.c b/gcc/testsuite/gcc.target/riscv/rvv/vsetvl/ffload-6.c
new file mode 100644
index 0000000..1b32f4a
--- /dev/null
+++ b/gcc/testsuite/gcc.target/riscv/rvv/vsetvl/ffload-6.c
@@ -0,0 +1,29 @@
+/* { dg-do compile } */
+/* { dg-options "-march=rv32gcv -mabi=ilp32 -fno-tree-vectorize -fno-schedule-insns -fno-schedule-insns2" } */
+
+#include "riscv_vector.h"
+
+void f (int8_t * restrict in, int8_t * restrict out, int n, int m, int cond)
+{
+  size_t vl = 101;
+  size_t new_vl;
+  
+  for (size_t i = 0; i < n; i++)
+    {
+      vint8mf8_t v = __riscv_vle8_v_i8mf8 (in + i, vl);
+      __riscv_vse8_v_i8mf8 (out + i, v, vl);
+      
+      vbool64_t mask = __riscv_vlm_v_b64 (in + i + 100, vl);
+      
+      vint8mf8_t v2 = __riscv_vle8ff_v_i8mf8_tumu (mask, v, in + i + 100, &new_vl, vl);
+      __riscv_vse8_v_i8mf8 (out + i + 100, v2, vl);
+    }
+
+  for (size_t i = 0; i < n; i++)
+    {
+      vint8mf8_t v = __riscv_vle8_v_i8mf8 (in + i + 300, new_vl);
+      __riscv_vse8_v_i8mf8 (out + i + 300, v, new_vl);
+    }
+}
+
+/* { dg-final { scan-assembler-times {vsetvli\s+zero,\s*[a-x0-9]+,\s*e8,\s*mf8,\s*t[au],\s*m[au]} 3 { target { no-opts "-O0" no-opts "-g" no-opts "-funroll-loops" } } } } */
diff --git a/gcc/testsuite/gcc.target/riscv/rvv/vsetvl/ffload-7.c b/gcc/testsuite/gcc.target/riscv/rvv/vsetvl/ffload-7.c
new file mode 100644
index 0000000..1c08b75
--- /dev/null
+++ b/gcc/testsuite/gcc.target/riscv/rvv/vsetvl/ffload-7.c
@@ -0,0 +1,32 @@
+/* { dg-do compile } */
+/* { dg-options "-march=rv32gcv -mabi=ilp32 -fno-tree-vectorize -fno-schedule-insns -fno-schedule-insns2" } */
+
+#include "riscv_vector.h"
+
+void f (int8_t * restrict in, int8_t * restrict out, int n, int m, int cond)
+{
+  size_t vl = 101;
+  if (cond)
+    vl = m * 2;
+  else
+    vl = m * 2 * vl;
+  
+  for (size_t i = 0; i < n; i++)
+    {
+      vint8mf8_t v = __riscv_vle8_v_i8mf8 (in + i, vl);
+      __riscv_vse8_v_i8mf8 (out + i, v, vl);
+      
+      vbool64_t mask = __riscv_vlm_v_b64 (in + i + 100, vl);
+      
+      vint8mf8_t v2 = __riscv_vle8ff_v_i8mf8_tumu (mask, v, in + i + 100, &vl, vl);
+      __riscv_vse8_v_i8mf8 (out + i + 100, v2, vl);
+    }
+
+  for (size_t i = 0; i < n; i++)
+    {
+      vint8mf8_t v = __riscv_vle8_v_i8mf8 (in + i + 300, vl);
+      __riscv_vse8_v_i8mf8 (out + i + 300, v, vl);
+    }
+}
+
+/* { dg-final { scan-assembler-times {vsetvli\s+zero,\s*[a-x0-9]+,\s*e8,\s*mf8,\s*tu,\s*mu} 1 { target { no-opts "-O0" no-opts "-g" no-opts "-funroll-loops" } } } } */