Thanks for the comments.
I just noticed there is already a downstream implementation in the SiFive
riscv-gcc tree:
https://github.com/riscv/zibi/issues/2
Sorry that I missed that before sending this RFC.
Since there is already an existing implementation, I will stop pursuing this
RFC to avoid duplicating the work. Please feel free to upstream the
downstream
patch directly if you prefer. I am happy to help test it and adapt it
against
current GCC trunk if needed.
Best regards,
Jiawei
在 2026/6/4 20:47, Kito Cheng 写道:
diff --git a/gcc/config/riscv/riscv-ext.def b/gcc/config/riscv/riscv-ext.def
index b9ef0c5ea05..ef8d0400f5d 100644
--- a/gcc/config/riscv/riscv-ext.def
+++ b/gcc/config/riscv/riscv-ext.def
@@ -220,6 +220,19 @@ DEFINE_RISCV_EXT(
/* BITMASK_BIT_POSITION*/ 7,
/* EXTRA_EXTENSION_FLAGS */ 0)
+DEFINE_RISCV_EXT(
+ /* NAME */ zibi,
+ /* UPPERCASE_NAME */ ZIBI,
+ /* FULL_NAME */ "Branch with immediate",
+ /* DESC */ "",
+ /* URL */ ,
+ /* DEP_EXTS */ ({}),
+ /* SUPPORTED_VERSIONS */ ({{1, 0}}),
It's 0.6 on the repo?
diff --git a/gcc/config/riscv/riscv.md b/gcc/config/riscv/riscv.md
index 2055e5c4a9d..38fd5d9e9ac 100644
--- a/gcc/config/riscv/riscv.md
+++ b/gcc/config/riscv/riscv.md
@@ -3435,6 +3435,32 @@
[(set_attr "type" "branch")
(set_attr "mode" "none")])
+(define_insn "*branch_zibi<mode>"
I incline this merge with *branch<mode> pattern and then split that
into eqne and others
(e.g. *branch<mode>_eqne *branch<mode>_relational_comparison)
and control the zibi by `ext` attribute
+ [(set (pc)
+ (if_then_else
+ (match_operator 1 "equality_operator"
+ [(match_operand:X 2 "register_operand" "r")
+ (match_operand:X 3 "zibi_cimm_operand" "zibi")])
+ (label_ref (match_operand 0 "" ""))
+ (pc)))]
