Honza, For example g++.dg/abi/vcall1.C fails at a call in a "localalias" function, which jumps to a bad location:
(gdb) up #1 0x100004c0 in B::B() [clone .localalias.2] () (gdb) x/16i $pc-32 0x100004a0 <_ZN1BC2Ev+156>: add r10,r10,r8 0x100004a4 <_ZN1BC2Ev+160>: mr r3,r10 0x100004a8 <_ZN1BC2Ev+164>: stw r2,20(r1) 0x100004ac <_ZN1BC2Ev+168>: lwz r10,0(r9) 0x100004b0 <_ZN1BC2Ev+172>: lwz r11,8(r9) 0x100004b4 <_ZN1BC2Ev+176>: mtctr r10 0x100004b8 <_ZN1BC2Ev.localalias.2+180>: lwz r2,4(r9) 0x100004bc <_ZN1BC2Ev.localalias.2+184>: bctrl => 0x100004c0 <_ZN1BC2Ev.localalias.2+188>: lwz r2,20(r1) 0x100004c4 <_ZN1BC2Ev.localalias.2+192>: addi r1,r31,64 0x100004c8 <_ZN1BC2Ev.localalias.2+196>: lwz r0,8(r1) 0x100004cc <_ZN1BC2Ev.localalias.2+200>: mtlr r0 0x100004d0 <_ZN1BC2Ev.localalias.2+204>: lwz r31,-4(r1) 0x100004d4 <_ZN1BC2Ev.localalias.2+208>: blr On Fri, May 30, 2014 at 3:20 AM, Richard Sandiford <rdsandif...@googlemail.com> wrote: > Jan Hubicka <hubi...@ucw.cz> writes: >>> Jan Hubicka <hubi...@ucw.cz> writes: >>> >> Richard Sandiford wrote the original section anchors implementation, >>> >> so he would be a good person to comment about the interaction between >>> >> aliases and section anchors. >>> > >>> > Thanks! Richard, does this patch seem sane? >>> >>> Looks good to me in principle, but with: >>> >>> > + struct symtab_node *snode; >>> > decl = SYMBOL_REF_DECL (symbol); >>> > + >>> > + snode = symtab_node (decl); >>> > + if (snode->alias) >>> > + { >>> > + rtx target = DECL_RTL (symtab_alias_ultimate_target >>> > (snode)->decl); >>> > + SYMBOL_REF_BLOCK_OFFSET (symbol) = SYMBOL_REF_BLOCK_OFFSET >>> > (target); >>> > + return; >>> > + } >>> >>> is SYMBOL_REF_BLOCK_OFFSET (target) guaranteed to be valid at this point? >>> It looked at face value like you'd need a recursive call to >>> place_block_symbol >>> on the target before the copy. >> >> My reading was that SYMBOL_REF_BLOCK_OFFSET is computed at DECL_RTL >> calculation time. But you are right - it is done by validize_mem that >> is not done by DECL_RTL. Shall I just call it on target first? > > Yeah, sounds like calling place_block_symbol would be safer. > > IIRC, the reason I didn't do it at SET_DECL_RTL time is that some frontends > tended to create placeholder decls that for whatever reason ended up with > an initial DECL_RTL, then changed the properties of the decl later once > more information was known. (This was all many years ago.) > > Thanks, > Richard