ARM VERSION 1.2 Datový list stáhnout pdf (Strana 71)

Differences

Floating-point exceptions

The ADS tools have been changed to conform to the IEEE specification. The

SDT2.50/2.51 tools set the default response to floating-point Invalid-Operation,

Divide-By-Zero and Overflow to be a trap causing program termination. This is

contrary to IEEE 754 section 7, that states that “The default response to an exception

shall be to proceed without a trap.”

Impact

To restore exception handling to the SDT 2.50/2.51 default, make the call shown in

Example 2-1 before using any floating-point operations. The call should preferably be

at the beginning of

main()

Example 2-1

#include <fenv.h>

#define EXCEPTIONS (FE_IEEE_MASK_INVALID | FE_IEEE_MASK_DIVBYZERO | \

FE_IEEE_MASK_OVERFLOW)

__ieee_status(EXCEPTIONS, EXCEPTIONS);

Stack unwinding

The compilers now always generate DWARF2 stack-unwinding descriptions. In SDT

2.50/2.51 they were only generated if the

-g

option was specified (for debug

information). The assembler generates stack-unwinding descriptions if the new frame

directives are used. The debuggers rely on the stack-unwinding descriptions for stack

backtrace.

Impact

If you want to unwind stacks when debugging assembler code, ensure that you use the

new frame directives. Stack-unwinding descriptions are automatically generated by the

ADS compilers and are included in the libraries released with ADS, so you have to

change only assembly language code and legacy SDT2.50/2.51 code not compiled with

debug information (

-g

option). You can examine disassembled output from the

compilers to see how to use the assembler frame directives correctly.

Source directory variable in armsd and ADW

The

$sourcedir

variable used by armsd and ADW defaults to NULL if no value is

specified. In addition, the delimiter used to separate multiple pathnames has been

changed from a space to a semicolon.

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ARM VERSION 1.2 Datový list Strana 71