-Werror,-Wtautological-overlap-compare error in h8300-tdep.c
Yoshinori Sato
ysato@users.sourceforge.jp
Mon May 25 09:52:52 GMT 2020
On Wed, 20 May 2020 02:35:12 +0900,
Simon Marchi wrote:
>
> On 2020-05-18 8:51 a.m., Yoshinori Sato wrote:
> > Yes.
> > register number 6 (er6) is frame pointer in h8300 ABI.
> > Since we are analyzing the code that accesses the stack frame,
> > we will only look at the frame pointer.
>
> Ah ok, thanks for the explanation. Here's what I pushed. Note that I also
> changed the read_memory_integer to read_memory_unsigned_integer.
>
Sorry too late reply.
It looks good. Thanks.
>
> From 1d6ce4d31257e1ea49b3a1b257055bf8f7ff16af Mon Sep 17 00:00:00 2001
> From: Yoshinori Sato <ysato@users.sourceforge.jp>
> Date: Tue, 19 May 2020 13:33:08 -0400
> Subject: [PATCH] gdb: fix -Wtautological-overlap-compare error in h8300-tdep.c
>
> Compiling with clang 11 gives us:
>
> CXX h8300-tdep.o
> /home/smarchi/src/binutils-gdb/gdb/h8300-tdep.c:225:21: error: overlapping comparisons always evaluate to false [-Werror,-Wtautological-overlap-compare]
> if (disp < 0 && disp > 0xffffff)
> ~~~~~~~~~^~~~~~~~~~~~~~~~~~
> /home/smarchi/src/binutils-gdb/gdb/h8300-tdep.c:203:17: error: overlapping comparisons always evaluate to false [-Werror,-Wtautological-overlap-compare]
> if (disp < 0 && disp > 0xffffff)
> ~~~~~~~~~^~~~~~~~~~~~~~~~~~
> /home/smarchi/src/binutils-gdb/gdb/h8300-tdep.c:184:17: error: overlapping comparisons always evaluate to false [-Werror,-Wtautological-overlap-compare]
> if (disp < 0 && disp > 0xffffff)
> ~~~~~~~~~^~~~~~~~~~~~~~~~~~
>
> Indeed, disp (of type LONGEST) can't be less than 0 and greater than
> 0xffffff.
>
> Fix it by changing the way we check if disp is negative. Check the sign
> bit of disp, which is a 24-bit number.
>
> gdb/ChangeLog:
>
> * h8300-tdep.c (h8300_is_argument_spill): Change how we check
> whether disp is negative.
> ---
> gdb/ChangeLog | 5 +++++
> gdb/h8300-tdep.c | 13 +++++++------
> 2 files changed, 12 insertions(+), 6 deletions(-)
>
> diff --git a/gdb/ChangeLog b/gdb/ChangeLog
> index f086b5cf908c..c4393182dd95 100644
> --- a/gdb/ChangeLog
> +++ b/gdb/ChangeLog
> @@ -1,3 +1,8 @@
> +2020-05-19 Yoshinori Sato <ysato@users.sourceforge.jp>
> +
> + * h8300-tdep.c (h8300_is_argument_spill): Change how we check
> + whether disp is negative.
> +
> 2020-05-19 Simon Marchi <simon.marchi@efficios.com>
>
> * symfile.h (struct symfile_segment_data)
> diff --git a/gdb/h8300-tdep.c b/gdb/h8300-tdep.c
> index 3c2f502a124d..b569a23f2631 100644
> --- a/gdb/h8300-tdep.c
> +++ b/gdb/h8300-tdep.c
> @@ -178,10 +178,10 @@ h8300_is_argument_spill (struct gdbarch *gdbarch, CORE_ADDR pc)
> if (IS_MOVB_Rn24_SP (read_memory_unsigned_integer (pc + 2,
> 2, byte_order)))
> {
> - LONGEST disp = read_memory_integer (pc + 4, 4, byte_order);
> + ULONGEST disp = read_memory_unsigned_integer (pc + 4, 4, byte_order);
>
> /* ... and d:24 is negative. */
> - if (disp < 0 && disp > 0xffffff)
> + if ((disp & 0x00800000) != 0)
> return 8;
> }
> }
> @@ -197,10 +197,10 @@ h8300_is_argument_spill (struct gdbarch *gdbarch, CORE_ADDR pc)
> if (IS_MOVW_Rn24_SP (read_memory_unsigned_integer (pc + 2,
> 2, byte_order)))
> {
> - LONGEST disp = read_memory_integer (pc + 4, 4, byte_order);
> + ULONGEST disp = read_memory_unsigned_integer (pc + 4, 4, byte_order);
>
> /* ... and d:24 is negative. */
> - if (disp < 0 && disp > 0xffffff)
> + if ((disp & 0x00800000) != 0)
> return 8;
> }
> }
> @@ -219,10 +219,11 @@ h8300_is_argument_spill (struct gdbarch *gdbarch, CORE_ADDR pc)
> {
> if (IS_MOVL_Rn24_SP (read_memory_integer (pc + 4, 2, byte_order)))
> {
> - LONGEST disp = read_memory_integer (pc + 6, 4, byte_order);
> + ULONGEST disp = read_memory_unsigned_integer (pc + 6, 4,
> + byte_order);
>
> /* ... and d:24 is negative. */
> - if (disp < 0 && disp > 0xffffff)
> + if ((disp & 0x00800000) != 0)
> return 10;
> }
> }
> --
> 2.26.2
>
--
Yosinori Sato
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