Re: [PATCH] RISC-V: vsetvl: Refine REG_EQUAL equality.

[Robin Dapp]

As per Jeff's remark I'm going to push the attached.

Regards
 Robin

Subject: [PATCH v4] RISC-V: vsetvl: Refine REG_EQUAL equality.

This patch enhances the equality check for REG_EQUAL notes in the vsetvl
pass by using the == operator instead of rtx_equal_p.  With that, in
situations like the following, a5 and a7 are not considered equal
anymore.

(insn 62 60 63 4 (set (reg:DI 17 a7 [orig:154 loop_len_54 ] [154])
        (umin:DI (reg:DI 15 a5 [orig:174 _100 ] [174])
            (reg:DI 30 t5 [219]))) 442 {umindi3}
     (expr_list:REG_EQUAL (umin:DI (reg:DI 15 a5 [orig:174 _100 ] [174])
            (const_int 8 [0x8]))
        (nil)))
(insn 63 62 65 4 (set (reg:DI 15 a5 [orig:175 _103 ] [175])
        (minus:DI (reg:DI 15 a5 [orig:174 _100 ] [174])
            (reg:DI 17 a7 [orig:154 loop_len_54 ] [154]))) 11 {subdi3}
     (nil))
(insn 65 63 66 4 (set (reg:DI 16 a6 [orig:153 loop_len_53 ] [153])
        (umin:DI (reg:DI 15 a5 [orig:175 _103 ] [175])
            (reg:DI 30 t5 [219]))) 442 {umindi3}
     (expr_list:REG_EQUAL (umin:DI (reg:DI 15 a5 [orig:175 _103 ] [175])
            (const_int 8 [0x8]))
        (nil)))

gcc/ChangeLog:

        * config/riscv/riscv-vsetvl.cc (source_equal_p): Use pointer
        equality for REG_EQUAL.

gcc/testsuite/ChangeLog:

        * gcc.target/riscv/rvv/autovec/partial/multiple_rgroup_zbb.c: New test.
---
 gcc/config/riscv/riscv-vsetvl.cc              |  6 ++++-
 .../rvv/autovec/partial/multiple_rgroup_zbb.c | 23 +++++++++++++++++++
 2 files changed, 28 insertions(+), 1 deletion(-)
 create mode 100644 
gcc/testsuite/gcc.target/riscv/rvv/autovec/partial/multiple_rgroup_zbb.c

diff --git a/gcc/config/riscv/riscv-vsetvl.cc b/gcc/config/riscv/riscv-vsetvl.cc
index 3fa25a6404d..8466b5d019e 100644
--- a/gcc/config/riscv/riscv-vsetvl.cc
+++ b/gcc/config/riscv/riscv-vsetvl.cc
@@ -560,7 +560,11 @@ source_equal_p (insn_info *insn1, insn_info *insn2)
 
   rtx note1 = find_reg_equal_equiv_note (rinsn1);
   rtx note2 = find_reg_equal_equiv_note (rinsn2);
-  if (note1 && note2 && rtx_equal_p (note1, note2))
+  /* We could handle the case of similar-looking REG_EQUALs as well but
+     would need to verify that no insn in between modifies any of the source
+     operands.  */
+  if (note1 && note2 && rtx_equal_p (note1, note2)
+      && REG_NOTE_KIND (note1) == REG_EQUIV)
     return true;
   return false;
 }
diff --git 
a/gcc/testsuite/gcc.target/riscv/rvv/autovec/partial/multiple_rgroup_zbb.c 
b/gcc/testsuite/gcc.target/riscv/rvv/autovec/partial/multiple_rgroup_zbb.c
new file mode 100644
index 00000000000..15178a2c848
--- /dev/null
+++ b/gcc/testsuite/gcc.target/riscv/rvv/autovec/partial/multiple_rgroup_zbb.c
@@ -0,0 +1,23 @@
+/* { dg-do compile } *.
+/* { dg-options "-march=rv64gcv_zbb -mabi=lp64d -O2 --param 
riscv-autovec-preference=fixed-vlmax -fno-schedule-insns -fno-schedule-insns2" 
} */
+
+#include <stdint-gcc.h>
+
+void __attribute__ ((noipa))
+test (uint16_t *__restrict f, uint32_t *__restrict d, uint64_t *__restrict e,
+      uint16_t x, uint16_t x2, uint16_t x3, uint16_t x4, uint32_t y,
+      uint32_t y2, uint64_t z, int n)
+{
+  for (int i = 0; i < n; ++i)
+    {
+      f[i * 4 + 0] = x;
+      f[i * 4 + 1] = x2;
+      f[i * 4 + 2] = x3;
+      f[i * 4 + 3] = x4;
+      d[i * 2 + 0] = y;
+      d[i * 2 + 1] = y2;
+      e[i] = z;
+    }
+}
+
+/* { dg-final { scan-assembler-times 
"vsetvli\tzero,\s*\[a-z0-9\]+,\s*e16,\s*m1,\s*ta,\s*ma" 4 } } */
-- 
2.41.0