On 7/19/2026 6:17 AM, Jin Ma wrote:
No new macro-fusion functionality is added. Include both
instruction UIDs in dump messages so consecutive matches can be
distinguished, and report ZEXTW and ZEXTWS with their actual fusion types.
Document existing fusion recognizers consistently to make their RTL
relationships and constraints easier to understand.
Keep each table entry tied to one fusion operation and use the common
enablement helper.
gcc/ChangeLog:
* config/riscv/riscv-fusion.cc (riscv_fuse_zextw_common): New function.
(riscv_fuse_zextw): Likewise.
(riscv_fuse_zextws): Use riscv_fuse_zextw_common and document RTL
relationships and constraints.
(riscv_fuse_zexth): Use riscv_fuse_zextw_common.
(riscv_fuse_ldindexed): Document RTL relationships and constraints.
(riscv_fuse_expanded_ld): Likewise.
(riscv_fuse_ldpreincrement): Likewise.
(riscv_fuse_lui_addi): Likewise.
(riscv_fuse_auipc_addi): Likewise.
(riscv_fuse_lui_ld): Likewise.
(riscv_fuse_auipc_ld): Likewise.
(riscv_fuse_cache_aligned_std): Likewise.
(riscv_fuse_aligned_std): Likewise.
(riscv_fuse_bfext): Likewise.
(riscv_fuse_b_alui): Likewise.
(riscv_fusion_entry::op): Rename from op_flags and use an enum.
(riscv_fusion_table): Split ZEXTW and ZEXTWS entries.
(riscv_macro_fusion_pair_p): Use riscv_fusion_enabled_p and print
instruction UIDs.
gcc/testsuite/ChangeLog:
* gcc.target/riscv/fusion-zextw-2.c: Expect the ZEXTW dump name.
* gcc.target/riscv/fusion-zextw.c: Likewise.
---
+/* Check for RISCV_FUSE_ZEXTWS fusion.
+ prev (slli) == (set (reg:DI rd1)
+ (ashift:DI (reg:DI rs1) (const_int 32)))
+ curr (srli) == (set (reg:DI rd2)
+ (lshiftrt:DI (reg:DI rd1) (const_int imm5)))
+
+ Constraints:
+ rd1 == rd2. */
+
+static bool
+riscv_fuse_zextws (rtx_insn *prev, rtx_insn *curr)
+{
+ if (riscv_fuse_zextw_common (prev, curr, 32, true))
+ return true;
+
+ return false;
Isn't this just return riscv_fuse_zext_common (...), ie, no need for a
conditional in here.
+}
+
+
+static bool
+riscv_fuse_zexth (rtx_insn *prev, rtx_insn *curr)
+{
+ if (riscv_fuse_zextw_common (prev, curr, 48, false))
return true;
return false;
Similarly. And I think zextw_common might be better as zext_common
since I think that routine is getting used for various forms, not just
those that are zextw.
}
@@ -700,9 +826,8 @@ typedef bool (*fusion_checker_fn) (rtx_insn *, rtx_insn *);
struct riscv_fusion_entry
{
- /* The fusion operation flag to check enablement. For entries that
- check multiple flags (ZEXTW/ZEXTWS), use the bitwise OR. */
- unsigned int op_flags;
+ /* The fusion operation to check enablement. */
+ enum riscv_fusion_pairs op;
This seems wrong. We're not dealing with an enumeration here, but a
bitmask of enabled fusion capabilities Right?
Basically OK. Just those minor issues I see.
