I kept hoping I'd see a better solution, perhaps one where chunks of
this routine just go away, but that hasn't materialized. So...
This patch avoids infinite recursion through riscv_legitimize_move.
Essentially we end up calling it recursively with arguments that are a
nop-move and those particular arguments trigger infinite recursion.
So this patch just recognizes and elides the nop move. Bootstrapped on
riscv64-linux-gnu and regression tested on riscv{32,64}-elf with no
regressions. Pushing to the trunk.
jeff
commit 45f9d4970c13314499aa53ba843873d095105d0f
Author: Jeff Law <[email protected]>
Date: Sun Feb 8 08:23:07 2026 -0700
Patch for testing
diff --git a/gcc/config/riscv/riscv.cc b/gcc/config/riscv/riscv.cc
index 25749af14366..3baf0a936b58 100644
--- a/gcc/config/riscv/riscv.cc
+++ b/gcc/config/riscv/riscv.cc
@@ -3912,9 +3912,16 @@ riscv_legitimize_move (machine_mode mode, rtx dest, rtx
src)
}
}
+ /* If we are extracting a single element out of a vector and do
+ not need an intermediate register, then the extraction will
+ occur directly into RESULT. RESULT is the same as DEST and
+ INT_REG. So we end up with a nop move. That is not a major
+ problem, except in this case it'll send us right back into
+ this code and we recurse. Given we put the value in RESULT
+ already we can just elide the nop move here and be done. */
if (need_int_reg_p)
emit_move_insn (dest, gen_lowpart (GET_MODE (dest), int_reg));
- else
+ else if (!rtx_equal_p (dest, int_reg))
emit_move_insn (dest, int_reg);
return true;
}
diff --git a/gcc/testsuite/gcc.target/riscv/pr123911.c
b/gcc/testsuite/gcc.target/riscv/pr123911.c
new file mode 100644
index 000000000000..30abe7ac76dd
--- /dev/null
+++ b/gcc/testsuite/gcc.target/riscv/pr123911.c
@@ -0,0 +1,15 @@
+/* { dg-do compile */
+/* { dg-options "-march=rv64gv -mabi=lp64d" { target { rv64 } } } */
+/* { dg-options "-march=rv32gv -mabi=ilp32" { target { rv32 } } } */
+
+typedef __attribute__((__vector_size__(8))) char W;
+typedef __attribute__((__vector_size__(64))) short V;
+
+V
+foo(V v, W w)
+{
+ __builtin_memmove(30 + (char *)&v, &w, 1);
+ __builtin_memmove(&v, &w, 8);
+ return v;
+}
+
