Jeff Law tells me h8300-elf fails gcc.c-torture/compile/pr49029.c with -O2 -g -mint32 -mh. This patch fixes it.
The problem is that strict low part handling in cselib_record_sets assumes src_elt is not NULL. That src_elt is taken from a strict low part set, but it won't always have a src_elt to begin with. In this case, it's because src is a volatile MEM; we don't record values for those. Although we could fix the problem by testing for a NULL src_elt before creating the zero extends corresponding to strict low part sets of formerly const0_rtx REGs, there's no point in recording the additional set that we won't be able to use anyway. We could still record that the whole register has a zero-extend of the value stored in the narrower-mode strict low part of the register, but is that of any use? I guess not, but if we find otherwise, we can change that later. Jeff tested this with a cross compiler to h8300-elf, and several other native and cross toolchains IIUC. I'm regstrapping it myself on i686- and x86_64-linux-gnu. Ok to install? for gcc/ChangeLog * cselib.c (cselib_record_sets): Skip strict low part sets with NULL src_elt. --- gcc/cselib.c | 1 + 1 file changed, 1 insertion(+) diff --git a/gcc/cselib.c b/gcc/cselib.c index 6d3a4078c689..4a68439455fd 100644 --- a/gcc/cselib.c +++ b/gcc/cselib.c @@ -2616,6 +2616,7 @@ cselib_record_sets (rtx_insn *insn) preserves the upper bits that di:SI=zero_extend(flags:CCNO<=0). */ scalar_int_mode mode; if (dest != orig + && sets[i].src_elt && cselib_record_sets_hook && REG_P (dest) && HARD_REGISTER_P (dest) -- Alexandre Oliva, freedom fighter https://FSFLA.org/blogs/lxo Be the change, be Free! FSF Latin America board member GNU Toolchain Engineer Free Software Evangelist Hay que enGNUrecerse, pero sin perder la terGNUra jamás-GNUChe