AVL propagation currently assumes that it can propagate a constant AVL into any vector insn and trips an assert if the insn fails to recognize after such a propagation.
However, for xtheadvector that is not a correct assumption; xtheadvector does not allow the vector length to be a constant integer (other than zero which allowed via x0).
After consulting with Jin Ma (thanks!) we agree the right fix is to avoid creating the immediate AVL for xtheadvector.
This has been tested in my tester, just waiting for the pre-commit tester to spin it.
Jeff
diff --git a/gcc/config/riscv/riscv-avlprop.cc b/gcc/config/riscv/riscv-avlprop.cc index bb4aceb75064..3031c29ae63c 100644 --- a/gcc/config/riscv/riscv-avlprop.cc +++ b/gcc/config/riscv/riscv-avlprop.cc @@ -508,7 +508,7 @@ pass_avlprop::execute (function *fn) simplify_replace_vlmax_avl (rinsn, prop.second); } - if (rvv_vector_bits == RVV_VECTOR_BITS_ZVL) + if (rvv_vector_bits == RVV_VECTOR_BITS_ZVL && !TARGET_XTHEADVECTOR) { /* Simplify VLMAX AVL into immediate AVL. E.g. Simplify this following case: diff --git a/gcc/testsuite/gcc.target/riscv/rvv/xtheadvector/pr120642.c b/gcc/testsuite/gcc.target/riscv/rvv/xtheadvector/pr120642.c new file mode 100644 index 000000000000..1a72580ad605 --- /dev/null +++ b/gcc/testsuite/gcc.target/riscv/rvv/xtheadvector/pr120642.c @@ -0,0 +1,4 @@ +/* { dg-do compile } */ +/* { dg-options "-O -mcpu=xt-c920 -mrvv-vector-bits=zvl" } */ +int __attribute__((__vector_size__(4 * sizeof(int)))) v; +void foo() { v /= 3; }