From a1322d76ca1c3c914fb818d9ba3edc291ccfa25e Mon Sep 17 00:00:00 2001
From: Ju-Zhe Zhong <juzhe.zhong@rivai.ai>
Date: Sun, 16 Jul 2023 08:31:22 +0800
Subject: [PATCH] RISC-V: Bugfix for riscv-vsetvl pass.
This patch comes from part of below change, which locate one bug of rvv
vsetvel pass when auto-vectorization.
https://gcc.gnu.org/pipermail/gcc-patches/2023-July/624523.html
Unforunately, It is not easy to reproduce this bug by intrinsic APIs
but it is worth to backport to GCC 13.
Signed-off-by: Ju-Zhe Zhong <juzhe.zhong@rivai.ai>
gcc/ChangeLog:
* config/riscv/riscv-vsetvl.cc (gen_vsetvl_pat): Add vl parameter.
(change_vsetvl_insn): Ditto.
(change_insn): Add validate change as well as assert.
(pass_vsetvl::backward_demand_fusion): Allow forward.
---
gcc/config/riscv/riscv-vsetvl.cc | 29 +++++++++++++++++++++++------
1 file changed, 23 insertions(+), 6 deletions(-)
diff --git a/gcc/config/riscv/riscv-vsetvl.cc b/gcc/config/riscv/riscv-vsetvl.cc
index 3355ca4e3fb5..fbd269881064 100644
--- a/gcc/config/riscv/riscv-vsetvl.cc
+++ b/gcc/config/riscv/riscv-vsetvl.cc
@@ -633,7 +633,8 @@ gen_vsetvl_pat (enum vsetvl_type insn_type, const vl_vtype_info &info, rtx vl)
}
static rtx
-gen_vsetvl_pat (rtx_insn *rinsn, const vector_insn_info &info)
+gen_vsetvl_pat (rtx_insn *rinsn, const vector_insn_info &info,
+ rtx vl = NULL_RTX)
{
rtx new_pat;
vl_vtype_info new_info = info;
@@ -644,7 +645,7 @@ gen_vsetvl_pat (rtx_insn *rinsn, const vector_insn_info &info)
if (vsetvl_insn_p (rinsn) || vlmax_avl_p (info.get_avl ()))
{
rtx dest = get_vl (rinsn);
- new_pat = gen_vsetvl_pat (VSETVL_NORMAL, new_info, dest);
+ new_pat = gen_vsetvl_pat (VSETVL_NORMAL, new_info, vl ? vl : dest);
}
else if (INSN_CODE (rinsn) == CODE_FOR_vsetvl_vtype_change_only)
new_pat = gen_vsetvl_pat (VSETVL_VTYPE_CHANGE_ONLY, new_info, NULL_RTX);
@@ -926,7 +927,8 @@ change_insn (rtx_insn *rinsn, rtx new_pat)
print_rtl_single (dump_file, PATTERN (rinsn));
}
- validate_change (rinsn, &PATTERN (rinsn), new_pat, false);
+ bool change_p = validate_change (rinsn, &PATTERN (rinsn), new_pat, false);
+ gcc_assert (change_p);
if (dump_file)
{
@@ -1039,7 +1041,8 @@ change_insn (function_info *ssa, insn_change change, insn_info *insn,
}
static void
-change_vsetvl_insn (const insn_info *insn, const vector_insn_info &info)
+change_vsetvl_insn (const insn_info *insn, const vector_insn_info &info,
+ rtx vl = NULL_RTX)
{
rtx_insn *rinsn;
if (vector_config_insn_p (insn->rtl ()))
@@ -1053,7 +1056,7 @@ change_vsetvl_insn (const insn_info *insn, const vector_insn_info &info)
rinsn = PREV_INSN (insn->rtl ());
gcc_assert (vector_config_insn_p (rinsn));
}
- rtx new_pat = gen_vsetvl_pat (rinsn, info);
+ rtx new_pat = gen_vsetvl_pat (rinsn, info, vl);
change_insn (rinsn, new_pat);
}
@@ -3331,7 +3334,21 @@ pass_vsetvl::backward_demand_fusion (void)
new_info))
continue;
- change_vsetvl_insn (new_info.get_insn (), new_info);
+ rtx vl = NULL_RTX;
+ /* Backward VLMAX VL:
+ bb 3:
+ vsetivli zero, 1 ... -> vsetvli t1, zero
+ vmv.s.x
+ bb 5:
+ vsetvli t1, zero ... -> to be elided.
+ vlse16.v
+
+ We should forward "t1". */
+ if (!block_info.reaching_out.has_avl_reg ()
+ && vlmax_avl_p (new_info.get_avl ()))
+ vl = get_vl (prop.get_insn ()->rtl ());
+ change_vsetvl_insn (new_info.get_insn (), new_info, vl);
+
if (block_info.local_dem == block_info.reaching_out)
block_info.local_dem = new_info;
block_info.reaching_out = new_info;
--
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