[PATCH GCC]Add 'force-dwarf-lexical-blocks' command line option

["Herman, Andrei" <Andrei_Herman at codesourcery dot com>]

Hi,

Currently GCC only emits DWARF debug information (DW_TAG_lexical_block DIEs)
for compound statements containing significant local declarations.
However, code coverage tools that process the DWARF debug information to
implement block/path coverage need more complete lexical block information. 

This patch adds the necessary functionality under the control of a new 
command line argument: -fforce-dwarf-lexical-blocks.

When this flag is set, a DW_TAG_lexical_block DIE will be emitted for every
function body, loop body, switch body, case statement, if-then and if-else
statement, even if the body is a single statement. 
Likewise, a lexical block will be emitted for the first label of a labeled
statement. This block ends at the end of the current lexical scope, or when
a break, continue, goto or return statement is encountered at the same lexical
scope level. 
Consequently, any case in a switch statement that does not flow through to 
the next case, will have its own dwarf lexical block.

The complete change proposal contains 4 patches (attached first 3):
1. Add command line option -fforce-dwarf-lexical-blocks
2. Use of flag_force_dwarf_blocks
3. Create label scopes

A forth patch, extending the proposed functionality to C++ will be submitted in a separate message.

Attached are the proposed ChangeLog additions, named according to the directory each one belongs to.

Best regards,
Andrei Herman
Mentor Graphics Corporation
Israel branch

Attachment: gcc_c_ChangeLog
Description: gcc_c_ChangeLog

Attachment: gcc_c-family_ChangeLog
Description: gcc_c-family_ChangeLog

Attachment: gcc_ChangeLog
Description: gcc_ChangeLog

Attachment: 0001-Add-command-line-option-fforce_dwarf_lexical_blocks.patch
Description: 0001-Add-command-line-option-fforce_dwarf_lexical_blocks.patch

Attachment: 0002-Use-flag_force_dwarf_blocks.patch
Description: 0002-Use-flag_force_dwarf_blocks.patch

Attachment: 0003-Create-label-scopes.patch
Description: 0003-Create-label-scopes.patch