RISC-V: Fix incorrect index(offset) of gather/scatter

I suddenly discovered I made a mistake that was lucky un-exposed.

https://godbolt.org/z/c3jzrh7or

GCC is using 32 bit index offset:

        vsll.vi v1,v1,2
        vsetvli zero,a5,e32,m1,ta,ma
        vluxei32.v      v1,(a1),v1

This is wrong since v1 may overflow 32bit after vsll.vi.

After this patch:

vsext.vf2	v8,v4
vsll.vi	v8,v8,2
vluxei64.v	v8,(a1),v8

Same as Clang.

Regression passed. Ok for trunk ?

gcc/ChangeLog:

	* config/riscv/autovec.md: Fix index bug.
	* config/riscv/riscv-protos.h (gather_scatter_valid_offset_mode_p): New function.
	* config/riscv/riscv-v.cc (expand_gather_scatter): Fix index bug.
	(gather_scatter_valid_offset_mode_p): New function.

gcc/testsuite/ChangeLog:

	* gcc.target/riscv/rvv/autovec/gather-scatter/offset_extend-1.c: New test.

4 files changed, 39 insertions, 17 deletions

diff --git a/gcc/config/riscv/autovec.md b/gcc/config/riscv/autovec.md
index 75948f5..6d51ce3 100644
--- a/gcc/config/riscv/autovec.md
+++ b/gcc/config/riscv/autovec.md
@@ -59,7 +59,7 @@
    (match_operand:<RATIO64:VM> 5 "vector_mask_operand")
    (match_operand 6 "autovec_length_operand")
    (match_operand 7 "const_0_operand")]
-  "TARGET_VECTOR"
+  "TARGET_VECTOR && riscv_vector::gather_scatter_valid_offset_mode_p (<RATIO64:MODE>mode)"
 {
   riscv_vector::expand_gather_scatter (operands, true);
   DONE;
@@ -74,7 +74,7 @@
    (match_operand:<RATIO32:VM> 5 "vector_mask_operand")
    (match_operand 6 "autovec_length_operand")
    (match_operand 7 "const_0_operand")]
-  "TARGET_VECTOR"
+  "TARGET_VECTOR && riscv_vector::gather_scatter_valid_offset_mode_p (<RATIO32:MODE>mode)"
 {
   riscv_vector::expand_gather_scatter (operands, true);
   DONE;
@@ -89,7 +89,7 @@
    (match_operand:<RATIO16:VM> 5 "vector_mask_operand")
    (match_operand 6 "autovec_length_operand")
    (match_operand 7 "const_0_operand")]
-  "TARGET_VECTOR"
+  "TARGET_VECTOR && riscv_vector::gather_scatter_valid_offset_mode_p (<RATIO16:MODE>mode)"
 {
   riscv_vector::expand_gather_scatter (operands, true);
   DONE;
@@ -104,7 +104,7 @@
    (match_operand:<RATIO8:VM> 5 "vector_mask_operand")
    (match_operand 6 "autovec_length_operand")
    (match_operand 7 "const_0_operand")]
-  "TARGET_VECTOR"
+  "TARGET_VECTOR && riscv_vector::gather_scatter_valid_offset_mode_p (<RATIO8:MODE>mode)"
 {
   riscv_vector::expand_gather_scatter (operands, true);
   DONE;
@@ -119,7 +119,7 @@
    (match_operand:<RATIO4:VM> 5 "vector_mask_operand")
    (match_operand 6 "autovec_length_operand")
    (match_operand 7 "const_0_operand")]
-  "TARGET_VECTOR"
+  "TARGET_VECTOR && riscv_vector::gather_scatter_valid_offset_mode_p (<RATIO4:MODE>mode)"
 {
   riscv_vector::expand_gather_scatter (operands, true);
   DONE;
@@ -134,7 +134,7 @@
    (match_operand:<RATIO2:VM> 5 "vector_mask_operand")
    (match_operand 6 "autovec_length_operand")
    (match_operand 7 "const_0_operand")]
-  "TARGET_VECTOR"
+  "TARGET_VECTOR && riscv_vector::gather_scatter_valid_offset_mode_p (<RATIO2:MODE>mode)"
 {
   riscv_vector::expand_gather_scatter (operands, true);
   DONE;
@@ -153,7 +153,7 @@
    (match_operand:<RATIO1:VM> 5 "vector_mask_operand")
    (match_operand 6 "autovec_length_operand")
    (match_operand 7 "const_0_operand")]
-  "TARGET_VECTOR"
+  "TARGET_VECTOR && riscv_vector::gather_scatter_valid_offset_mode_p (<RATIO1:MODE>mode)"
 {
   riscv_vector::expand_gather_scatter (operands, true);
   DONE;
@@ -172,7 +172,7 @@
    (match_operand:<RATIO64:VM> 5 "vector_mask_operand")
    (match_operand 6 "autovec_length_operand")
    (match_operand 7 "const_0_operand")]
-  "TARGET_VECTOR"
+  "TARGET_VECTOR && riscv_vector::gather_scatter_valid_offset_mode_p (<RATIO64:MODE>mode)"
 {
   riscv_vector::expand_gather_scatter (operands, false);
   DONE;
@@ -187,7 +187,7 @@
    (match_operand:<RATIO32:VM> 5 "vector_mask_operand")
    (match_operand 6 "autovec_length_operand")
    (match_operand 7 "const_0_operand")]
-  "TARGET_VECTOR"
+  "TARGET_VECTOR && riscv_vector::gather_scatter_valid_offset_mode_p (<RATIO32:MODE>mode)"
 {
   riscv_vector::expand_gather_scatter (operands, false);
   DONE;
@@ -202,7 +202,7 @@
    (match_operand:<RATIO16:VM> 5 "vector_mask_operand")
    (match_operand 6 "autovec_length_operand")
    (match_operand 7 "const_0_operand")]
-  "TARGET_VECTOR"
+  "TARGET_VECTOR && riscv_vector::gather_scatter_valid_offset_mode_p (<RATIO16:MODE>mode)"
 {
   riscv_vector::expand_gather_scatter (operands, false);
   DONE;
@@ -217,7 +217,7 @@
    (match_operand:<RATIO8:VM> 5 "vector_mask_operand")
    (match_operand 6 "autovec_length_operand")
    (match_operand 7 "const_0_operand")]
-  "TARGET_VECTOR"
+  "TARGET_VECTOR && riscv_vector::gather_scatter_valid_offset_mode_p (<RATIO8:MODE>mode)"
 {
   riscv_vector::expand_gather_scatter (operands, false);
   DONE;
@@ -232,7 +232,7 @@
    (match_operand:<RATIO4:VM> 5 "vector_mask_operand")
    (match_operand 6 "autovec_length_operand")
    (match_operand 7 "const_0_operand")]
-  "TARGET_VECTOR"
+  "TARGET_VECTOR && riscv_vector::gather_scatter_valid_offset_mode_p (<RATIO4:MODE>mode)"
 {
   riscv_vector::expand_gather_scatter (operands, false);
   DONE;
@@ -247,7 +247,7 @@
    (match_operand:<RATIO2:VM> 5 "vector_mask_operand")
    (match_operand 6 "autovec_length_operand")
    (match_operand 7 "const_0_operand")]
-  "TARGET_VECTOR"
+  "TARGET_VECTOR && riscv_vector::gather_scatter_valid_offset_mode_p (<RATIO2:MODE>mode)"
 {
   riscv_vector::expand_gather_scatter (operands, false);
   DONE;
@@ -266,7 +266,7 @@
    (match_operand:<RATIO1:VM> 5 "vector_mask_operand")
    (match_operand 6 "autovec_length_operand")
    (match_operand 7 "const_0_operand")]
-  "TARGET_VECTOR"
+  "TARGET_VECTOR && riscv_vector::gather_scatter_valid_offset_mode_p (<RATIO1:MODE>mode)"
 {
   riscv_vector::expand_gather_scatter (operands, false);
   DONE;
diff --git a/gcc/config/riscv/riscv-protos.h b/gcc/config/riscv/riscv-protos.h
index f6bd15b..8c9f7e0 100644
--- a/gcc/config/riscv/riscv-protos.h
+++ b/gcc/config/riscv/riscv-protos.h
@@ -544,6 +544,7 @@ opt_machine_mode vectorize_related_mode (machine_mode, scalar_mode,
 unsigned int autovectorize_vector_modes (vec<machine_mode> *, bool);
 bool cmp_lmul_le_one (machine_mode);
 bool cmp_lmul_gt_one (machine_mode);
+bool gather_scatter_valid_offset_mode_p (machine_mode);
 }
 
 /* We classify builtin types into two classes:
diff --git a/gcc/config/riscv/riscv-v.cc b/gcc/config/riscv/riscv-v.cc
index 64f99d8..a75eb59 100644
--- a/gcc/config/riscv/riscv-v.cc
+++ b/gcc/config/riscv/riscv-v.cc
@@ -3491,15 +3491,14 @@ expand_gather_scatter (rtx *ops, bool is_load)
 
   machine_mode vec_mode = GET_MODE (vec_reg);
   machine_mode idx_mode = GET_MODE (vec_offset);
-  scalar_mode inner_vec_mode = GET_MODE_INNER (vec_mode);
   scalar_mode inner_idx_mode = GET_MODE_INNER (idx_mode);
-  unsigned inner_vsize = GET_MODE_BITSIZE (inner_vec_mode);
   unsigned inner_offsize = GET_MODE_BITSIZE (inner_idx_mode);
   poly_int64 nunits = GET_MODE_NUNITS (vec_mode);
   poly_int64 value;
   bool is_vlmax = poly_int_rtx_p (len, &value) && known_eq (value, nunits);
 
-  if (inner_offsize < inner_vsize)
+  /* Extend the offset element to address width.  */
+  if (inner_offsize < BITS_PER_WORD)
     {
       /* 7.2. Vector Load/Store Addressing Modes.
 	 If the vector offset elements are narrower than XLEN, they are
@@ -3796,6 +3795,14 @@ cmp_lmul_gt_one (machine_mode mode)
   return false;
 }
 
+/* Return true if the gather/scatter offset mode is valid.  */
+bool
+gather_scatter_valid_offset_mode_p (machine_mode mode)
+{
+  machine_mode new_mode;
+  return get_vector_mode (Pmode, GET_MODE_NUNITS (mode)).exists (&new_mode);
+}
+
 /* We don't have to convert the floating point to integer when the
    mantissa is zero.  Thus, ther will be a limitation for both the
    single and double precision floating point.  There will be no
diff --git a/gcc/testsuite/gcc.target/riscv/rvv/autovec/gather-scatter/offset_extend-1.c b/gcc/testsuite/gcc.target/riscv/rvv/autovec/gather-scatter/offset_extend-1.c
new file mode 100644
index 0000000..b7936eb
--- /dev/null
+++ b/gcc/testsuite/gcc.target/riscv/rvv/autovec/gather-scatter/offset_extend-1.c
@@ -0,0 +1,14 @@
+/* { dg-do compile } */
+/* { dg-additional-options "-march=rv64gcv -mabi=lp64d" } */
+
+void
+f (int *restrict y, int *restrict x, int *restrict indices, int n)
+{
+  for (int i = 0; i < n; ++i)
+    y[i] = x[indices[i]] + 1;
+}
+
+/* { dg-final { scan-assembler {vluxei64\.v} } } */
+/* { dg-final { scan-assembler {vsll\.vi} } } */
+/* { dg-final { scan-assembler {vsext\.vf2} } } */
+/* { dg-final { scan-assembler-not {vluxei32\.v} } } */