From 9cab7ecda21c6499b0559f6e676fe222e26141be Mon Sep 17 00:00:00 2001 From: Ali Tamur Date: Tue, 27 Aug 2019 18:58:57 -0700 Subject: [PATCH] Fix float to LONGEST conversion. The code used to have undefined behaviour when template parameter is float and host_float is NaN, because it attempted to convert NaN value to LONGEST at the last statement. This frequently caused crashes on tests that checked "info all-registers" (at least when the code is compiled with clang; I didn't test with gdb). gdb/ChangeLog: *target-float.c (host_float_ops::to_longest): Update implementation. --- gdb/ChangeLog | 5 +++++ gdb/target-float.c | 17 +++++++++++------ 2 files changed, 16 insertions(+), 6 deletions(-) diff --git a/gdb/ChangeLog b/gdb/ChangeLog index 3b28884267b..eccd4ef2bdd 100644 --- a/gdb/ChangeLog +++ b/gdb/ChangeLog @@ -1,3 +1,8 @@ +2019-09-11 Ali Tamur + + *gdb/target-float.c (host_float_ops::to_longest): Update + implementation. + 2019-09-11 Christian Biesinger * dbxread.c (read_dbx_symtab): Update. diff --git a/gdb/target-float.c b/gdb/target-float.c index 39abb126965..0fd71c0dc33 100644 --- a/gdb/target-float.c +++ b/gdb/target-float.c @@ -1007,13 +1007,18 @@ host_float_ops::to_longest (const gdb_byte *addr, { T host_float; from_target (type, addr, &host_float); - /* Converting an out-of-range value is undefined behavior in C, but we - prefer to return a defined value here. */ - if (host_float > std::numeric_limits::max()) - return std::numeric_limits::max(); - if (host_float < std::numeric_limits::min()) + T min_possible_range = static_cast(std::numeric_limits::min()); + T max_possible_range = -min_possible_range; + /* host_float can be converted to an integer as long as it's in + the range [min_possible_range, max_possible_range). If not, it is either + too large, or too small, or is NaN; in this case return the maximum or + minimum possible value. */ + if (host_float < max_possible_range && host_float >= min_possible_range) + return static_cast (host_float); + if (host_float < min_possible_range) return std::numeric_limits::min(); - return (LONGEST) host_float; + /* This line will be executed if host_float is NaN. */ + return std::numeric_limits::max(); } /* Convert signed integer VAL to a target floating-number of type TYPE -- 2.30.2