optabs: make prepare_cmp_insn goto fail when cbranchcc4 checks unsatisfied
prepare_cmp_insn is a help function to generate comparison rtx.
It should not assume that cbranchcc4 exists and all sub-CC modes
are supported on a target. When the check fails, it could go to
fail and return a NULL rtx as its callers check the return value
for CCmode.
The test case (gcc.target/powerpc/cbranchcc4-1.c) which covers
failure path will be committed with an rs6000 specific patch.
2022-12-05 Haochen Gui <guihaoc@linux.ibm.com>
gcc/
* optabs.cc (prepare_cmp_insn): Return a NULL rtx other than
assertion failure when targets don't have cbranch optab or
predicate check fails.