From 8ba83e9109a1a02f54f1c4793c8f231bb9256acd Mon Sep 17 00:00:00 2001 From: Tom de Vries Date: Wed, 29 Jul 2020 09:03:20 +0200 Subject: [PATCH] [tdep/s390] Fix Wmaybe-uninitialized in s390_displaced_step_fixup When building gdb with CFLAGS/CXXFLAGS="-O2 -g -Wall", I see: ... src/gdb/s390-tdep.c: In function 'void s390_displaced_step_fixup(gdbarch*, \ displaced_step_closure*, CORE_ADDR, CORE_ADDR, regcache*)': src/gdb/s390-tdep.c:528:30: warning: 'r2' may be used uninitialized in this \ function [-Wmaybe-uninitialized] 528 | if (insn[0] == op_basr && r2 == 0) | ~~~~~~~~~~~~~~~~~~~^~~~~~~~~~ ... The problem is that the compiler is unaware that 'is_rr (insn, op_basr, &r1, &r2) == 1' ensures that 'insn[0] == op_basr': ... if (is_rr (insn, op_basr, &r1, &r2) || is_rx (insn, op_bas, &r1, &d2, &x2, &b2)) { /* Recompute saved return address in R1. */ regcache_cooked_write_unsigned (regs, S390_R0_REGNUM + r1, amode | (from + insnlen)); /* Update PC iff the instruction doesn't actually branch. */ if (insn[0] == op_basr && r2 == 0) regcache_write_pc (regs, from + insnlen); } ... Fix this by storing the result of the call, and using it instead of 'insn[0] ==op_basr'. Build on x86_64-linux with --enable-targets=s390-suse-linux,s390x-suse-linux. gdb/ChangeLog: 2020-07-29 Tom de Vries PR tdep/26280 * s390-tdep.c (s390_displaced_step_fixup): Fix Wmaybe-uninitialized. --- gdb/ChangeLog | 5 +++++ gdb/s390-tdep.c | 5 +++-- 2 files changed, 8 insertions(+), 2 deletions(-) diff --git a/gdb/ChangeLog b/gdb/ChangeLog index 9a9161561fd..4d4d62e302a 100644 --- a/gdb/ChangeLog +++ b/gdb/ChangeLog @@ -1,3 +1,8 @@ +2020-07-29 Tom de Vries + + PR tdep/26280 + * s390-tdep.c (s390_displaced_step_fixup): Fix Wmaybe-uninitialized. + 2020-07-28 Tom Tromey PR symtab/26270: diff --git a/gdb/s390-tdep.c b/gdb/s390-tdep.c index 0ee7a372563..65cb23705d2 100644 --- a/gdb/s390-tdep.c +++ b/gdb/s390-tdep.c @@ -518,14 +518,15 @@ s390_displaced_step_fixup (struct gdbarch *gdbarch, paddress (gdbarch, pc), insnlen, (int) amode); /* Handle absolute branch and save instructions. */ - if (is_rr (insn, op_basr, &r1, &r2) + int op_basr_p = is_rr (insn, op_basr, &r1, &r2); + if (op_basr_p || is_rx (insn, op_bas, &r1, &d2, &x2, &b2)) { /* Recompute saved return address in R1. */ regcache_cooked_write_unsigned (regs, S390_R0_REGNUM + r1, amode | (from + insnlen)); /* Update PC iff the instruction doesn't actually branch. */ - if (insn[0] == op_basr && r2 == 0) + if (op_basr_p && r2 == 0) regcache_write_pc (regs, from + insnlen); } -- 2.30.2