https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66870
--- Comment #10 from boger at us dot ibm.com --- Now that I am building on ppc64 with a new enough glibc, using my latest patches for rs6000.c and Andreas' patch, and forcing the gold linker to be used, I am hitting a testcase failure in the libgo fmt test. The failure is a segv, gdb shows this: 0x10024aa0 <fmt.free.pN6_fmt.ss>: ld r0,-28736(r13) 0x10024aa4 <fmt.free.pN6_fmt.ss+4>: addi r12,r1,-160 0x10024aa8 <fmt.free.pN6_fmt.ss+8>: nop 0x10024aac <fmt.free.pN6_fmt.ss+12>: cmpld cr7,r12,r0 0x10024ab0 <fmt.free.pN6_fmt.ss+16>: blt- cr7,0x10024b78 <fmt.free.pN6_fmt.ss+216> 0x10024ab4 <fmt.free.pN6_fmt.ss+20>: rldicl. r9,r4,8,56 => 0x10024ab8 <fmt.free.pN6_fmt.ss+24>: std r4,56(r12) 0x10024abc <fmt.free.pN6_fmt.ss+28>: std r5,64(r12) 0x10024ac0 <fmt.free.pN6_fmt.ss+32>: std r6,72(r12) 0x10024ac4 <fmt.free.pN6_fmt.ss+36>: std r7,80(r12) r12 does not contain the correct value. If look below in this function where the call to __morestack was, I see this: 0x10024b78 <fmt.free.pN6_fmt.ss+216>: mflr r0 0x10024b7c <fmt.free.pN6_fmt.ss+220>: std r0,16(r1) 0x10024b80 <fmt.free.pN6_fmt.ss+224>: bl 0x1004ed18 <.__morestack> 0x10024b84 <fmt.free.pN6_fmt.ss+228>: ld r0,16(r1) 0x10024b88 <fmt.free.pN6_fmt.ss+232>: mtlr r0 0x10024b8c <fmt.free.pN6_fmt.ss+236>: blr 0x10024b90 <fmt.free.pN6_fmt.ss+240>: b 0x10024ab4 <fmt.free.pN6_fmt.ss+20> For it to get to the code where the segv occurs, it must have taken the last branch after the call to __morestack. In reading the comments in the emit prologue code in rs6000.c, it says that __morestack returns the value in r29 and that should be moved to r12, but I don't see that happening in this code. Alan, can you look at this? I will send you the details on where it is.
