commit be7a73004583aab5d4c97cf55276ca58d5b3090b
Author: Mark Wielaard <mark@klomp.org>
Date:   Wed Dec 12 14:15:28 2018 +0100

    Mark helper regs defined in final_tidyup before freeres_wrapper call.
    
    In final_tidyup we setup the guest to call the freeres_wrapper, which
    will (possibly) call __gnu_cxx::__freeres() and/or __libc_freeres().
    
    In a couple of cases (ppc64be, ppc64le and mips32) this involves setting
    up one or more helper registers. Since we setup these guest registers
    we should make sure to mark them as fully defined. Otherwise we might
    see spurious warnings about undefined value usage if the guest register
    happened to not be fully defined before.
    
    This fixes PR402006.

diff --git a/coregrind/m_main.c b/coregrind/m_main.c
index 00702fc..22872a2 100644
--- a/coregrind/m_main.c
+++ b/coregrind/m_main.c
@@ -2304,22 +2304,35 @@ static void final_tidyup(ThreadId tid)
                    "Caught __NR_exit; running %s wrapper\n", msgs[to_run - 1]);
    }
       
-   /* set thread context to point to freeres_wrapper */
-   /* ppc64be-linux note: freeres_wrapper gives us the real
+   /* Set thread context to point to freeres_wrapper.
+      ppc64be-linux note: freeres_wrapper gives us the real
       function entry point, not a fn descriptor, so can use it
       directly.  However, we need to set R2 (the toc pointer)
       appropriately. */
    VG_(set_IP)(tid, freeres_wrapper);
+
 #  if defined(VGP_ppc64be_linux)
    VG_(threads)[tid].arch.vex.guest_GPR2 = r2;
+   VG_TRACK(post_reg_write, Vg_CoreClientReq, tid,
+            offsetof(VexGuestPPC64State, guest_GPR2),
+            sizeof(VG_(threads)[tid].arch.vex.guest_GPR2));
 #  elif  defined(VGP_ppc64le_linux)
    /* setting GPR2 but not really needed, GPR12 is needed */
    VG_(threads)[tid].arch.vex.guest_GPR2  = freeres_wrapper;
+   VG_TRACK(post_reg_write, Vg_CoreClientReq, tid,
+            offsetof(VexGuestPPC64State, guest_GPR2),
+            sizeof(VG_(threads)[tid].arch.vex.guest_GPR2));
    VG_(threads)[tid].arch.vex.guest_GPR12 = freeres_wrapper;
+   VG_TRACK(post_reg_write, Vg_CoreClientReq, tid,
+            offsetof(VexGuestPPC64State, guest_GPR12),
+            sizeof(VG_(threads)[tid].arch.vex.guest_GPR12));
 #  endif
    /* mips-linux note: we need to set t9 */
 #  if defined(VGP_mips32_linux) || defined(VGP_mips64_linux)
    VG_(threads)[tid].arch.vex.guest_r25 = freeres_wrapper;
+   VG_TRACK(post_reg_write, Vg_CoreClientReq, tid,
+            offsetof(VexGuestMIPS32State, guest_r25),
+            sizeof(VG_(threads)[tid].arch.vex.guest_r25));
 #  endif
 
    /* Pass a parameter to freeres_wrapper(). */