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avoid reading LineBlockFragmentHeader at all if the address is not in range, thus simplifying code and improving speed of execution

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Sahnvour 2019-03-15 21:44:12 +01:00
parent 094d40fb1a
commit 704dfaaabf
1 changed files with 16 additions and 14 deletions
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30
std/debug.zig
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@ -372,18 +372,20 @@ fn printSourceAtAddressWindows(di: *DebugInfo, out_stream: var, relocated_addres
const frag_vaddr_start = coff_section.header.virtual_address + line_hdr.RelocOffset;
const frag_vaddr_end = frag_vaddr_start + line_hdr.CodeSize;
// There is an unknown number of LineBlockFragmentHeaders (and their accompanying line and column records)
// from now on. We will iterate through them, and eventually find a LineInfo that we're interested in,
// breaking out to :subsections. If not, we will make sure to not read anything outside of this subsection.
const subsection_end_index = sect_offset + subsect_hdr.Length;
while (line_index < subsection_end_index) {
const block_hdr = @ptrCast(*pdb.LineBlockFragmentHeader, &subsect_info[line_index]);
line_index += @sizeOf(pdb.LineBlockFragmentHeader);
const start_line_index = line_index;
if (relative_address >= frag_vaddr_start and relative_address < frag_vaddr_end) {
// There is an unknown number of LineBlockFragmentHeaders (and their accompanying line and column records)
// from now on. We will iterate through them, and eventually find a LineInfo that we're interested in,
// breaking out to :subsections. If not, we will make sure to not read anything outside of this subsection.
const has_column = line_hdr.Flags.LF_HaveColumns;
const subsection_end_index = sect_offset + subsect_hdr.Length;
while (line_index < subsection_end_index) {
const block_hdr = @ptrCast(*pdb.LineBlockFragmentHeader, &subsect_info[line_index]);
line_index += @sizeOf(pdb.LineBlockFragmentHeader);
const start_line_index = line_index;
const has_column = line_hdr.Flags.LF_HaveColumns;
if (relative_address >= frag_vaddr_start and relative_address < frag_vaddr_end) {
// All line entries are stored inside their line block by ascending start address.
// Heuristic: we want to find the last line entry that has a vaddr_start <= relative_address.
// This is done with a simple linear search.
@ -427,11 +429,11 @@ fn printSourceAtAddressWindows(di: *DebugInfo, out_stream: var, relocated_addres
};
}
}
}
// Checking that we are not reading garbage after the (possibly) multiple block fragments.
if (line_index != subsection_end_index) {
return error.InvalidDebugInfo;
// Checking that we are not reading garbage after the (possibly) multiple block fragments.
if (line_index != subsection_end_index) {
return error.InvalidDebugInfo;
}
}
},
else => {},