| lldb debugging functionality for Gecko |
| ====================================== |
| |
| This directory contains a module, lldbutils, which is imported by the |
| in-tree .lldbinit file. The lldbutil modules define some lldb commands |
| that are handy for debugging Gecko. |
| |
| If you want to add a new command or Python-implemented type summary, either add |
| it to one of the existing broad area Python files (such as lldbutils/layout.py |
| for layout-related commands) or create a new file if none of the existing files |
| is appropriate. If you add a new file, make sure you add it to __all__ in |
| lldbutils/__init__.py. |
| |
| |
| Supported commands |
| ------------------ |
| |
| Most commands below that can take a pointer to an object also support being |
| called with a smart pointer like nsRefPtr or nsCOMPtr. |
| |
| |
| * frametree EXPR, ft EXPR |
| frametreelimited EXPR, ftl EXPR |
| |
| Shows information about a frame tree. EXPR is an expression that |
| is evaluated, and must be an nsIFrame*. frametree displays the |
| entire frame tree that contains the given frame. frametreelimited |
| displays a subtree of the frame tree rooted at the given frame. |
| |
| (lldb) p this |
| (nsBlockFrame *) $4 = 0x000000011687fcb8 |
| (lldb) ftl this |
| Block(div)(-1)@0x11687fcb8 {0,0,7380,690} [state=0002100000d04601] [content=0x11688c0c0] [sc=0x11687f990:-moz-scrolled-content]< |
| line 0x116899130: count=1 state=inline,clean,prevmarginclean,not impacted,not wrapped,before:nobr,after:nobr[0x100] {60,0,0,690} vis-overflow=60,510,0,0 scr-overflow=60,510,0,0 < |
| Text(0)""@0x1168990c0 {60,510,0,0} [state=0001000020404000] [content=0x11687ca10] [sc=0x11687fd88:-moz-non-element,parent=0x11687eb00] [run=0x115115e80][0,0,T] |
| > |
| > |
| (lldb) ft this |
| Viewport(-1)@0x116017430 [view=0x115efe190] {0,0,60,60} [state=000b063000002623] [sc=0x1160170f8:-moz-viewport]< |
| HTMLScroll(html)(-1)@0x1160180d0 {0,0,0,0} [state=000b020000000403] [content=0x115e4d640] [sc=0x116017768:-moz-viewport-scroll]< |
| ... |
| Canvas(html)(-1)@0x116017e08 {0,0,60,60} vis-overflow=0,0,8340,2196 scr-overflow=0,0,8220,2196 [state=000b002000000601] [content=0x115e4d640] [sc=0x11687e0f8:-moz-scrolled-canvas]< |
| Block(html)(-1)@0x11687e578 {0,0,60,2196} vis-overflow=0,0,8340,2196 scr-overflow=0,0,8220,2196 [state=000b100000d00601] [content=0x115e4d640] [sc=0x11687e4b8,parent=0x0]< |
| line 0x11687ec48: count=1 state=block,clean,prevmarginclean,not impacted,not wrapped,before:nobr,after:nobr[0x48] bm=480 {480,480,0,1236} vis-overflow=360,426,7980,1410 scr-overflow=480,480,7740,1236 < |
| Block(body)(1)@0x11687ebb0 {480,480,0,1236} vis-overflow=-120,-54,7980,1410 scr-overflow=0,0,7740,1236 [state=000b120000100601] [content=0x115ed8980] [sc=0x11687e990]< |
| line 0x116899170: count=1 state=inline,clean,prevmarginclean,not impacted,not wrapped,before:nobr,after:nobr[0x0] {0,0,7740,1236} vis-overflow=-120,-54,7980,1410 scr-overflow=0,0,7740,1236 < |
| nsTextControlFrame@0x11687f068 {0,66,7740,1170} vis-overflow=-120,-120,7980,1410 scr-overflow=0,0,7740,1170 [state=0002000000004621] [content=0x115ca2c50] [sc=0x11687ea40]< |
| HTMLScroll(div)(-1)@0x11687f6b0 {180,240,7380,690} [state=0002000000084409] [content=0x11688c0c0] [sc=0x11687eb00]< |
| Block(div)(-1)@0x11687fcb8 {0,0,7380,690} [state=0002100000d04601] [content=0x11688c0c0] [sc=0x11687f990:-moz-scrolled-content]< |
| line 0x116899130: count=1 state=inline,clean,prevmarginclean,not impacted,not wrapped,before:nobr,after:nobr[0x100] {60,0,0,690} vis-overflow=60,510,0,0 scr-overflow=60,510,0,0 < |
| Text(0)""@0x1168990c0 {60,510,0,0} [state=0001000020404000] [content=0x11687ca10] [sc=0x11687fd88:-moz-non-element,parent=0x11687eb00] [run=0x115115e80][0,0,T] |
| ... |
| |
| |
| * js |
| |
| Dumps the current JS stack. |
| |
| (lldb) js |
| 0 anonymous(aForce = false) ["chrome://browser/content/browser.js":13414] |
| this = [object Object] |
| 1 updateAppearance() ["chrome://browser/content/browser.js":13326] |
| this = [object Object] |
| 2 handleEvent(aEvent = [object Event]) ["chrome://browser/content/tabbrowser.xml":3811] |
| this = [object XULElement] |
| |
| |
| * prefcnt EXPR |
| |
| Shows the refcount of a given object. EXPR is an expression that is |
| evaluated, and can be either a pointer to or an actual refcounted |
| object. The object can be a standard nsISupports-like refcounted |
| object, a cycle-collected object or a mozilla::RefCounted<T> object. |
| |
| (lldb) p this |
| (nsHTMLDocument *) $1 = 0x0000000116e9d800 |
| (lldb) prefcnt this |
| 20 |
| (lldb) p mDocumentURI |
| (nsCOMPtr<nsIURI>) $3 = { |
| mRawPtr = 0x0000000117163e50 |
| } |
| (lldb) prefcnt mDocumentURI |
| 11 |
| |
| |
| * pstate EXPR |
| |
| Shows the frame state bits (using their symbolic names) of a given frame. |
| EXPR is an expression that is evaluated, and must be an nsIFrame*. |
| |
| (lldb) p this |
| (nsTextFrame *) $1 = 0x000000011f470b10 |
| (lldb) p/x mState |
| (nsFrameState) $2 = 0x0000004080604000 |
| (lldb) pstate this |
| TEXT_HAS_NONCOLLAPSED_CHARACTERS | TEXT_END_OF_LINE | TEXT_START_OF_LINE | NS_FRAME_PAINTED_THEBES | NS_FRAME_INDEPENDENT_SELECTION |
| |
| |
| * ptag EXPR |
| |
| Shows the DOM tag name of a node. EXPR is an expression that is |
| evaluated, and can be either an nsINode pointer or a concrete DOM |
| object. |
| |
| (lldb) p this |
| (nsHTMLDocument *) $0 = 0x0000000116e9d800 |
| (lldb) ptag this |
| (PermanentAtomImpl *) $1 = 0x0000000110133ac0 u"#document" |
| (lldb) p this->GetRootElement() |
| (mozilla::dom::HTMLSharedElement *) $2 = 0x0000000118429780 |
| (lldb) ptag $2 |
| (PermanentAtomImpl *) $3 = 0x0000000110123b80 u"html" |
| |
| |
| Supported type summaries and synthetic children |
| ----------------------------------------------- |
| |
| In lldb terminology, type summaries are rules for how to display a value |
| when using the "expression" command (or its familiar-to-gdb-users "p" alias), |
| and synthetic children are fake member variables or array elements also |
| added by custom rules. |
| |
| For objects that do have synthetic children defined for them, like nsTArray, |
| the "expr -R -- EXPR" command can be used to show its actual member variables. |
| |
| |
| * nsAString, nsACString, |
| nsFixedString, nsFixedCString, |
| nsAutoString, nsAutoCString |
| |
| Strings have a type summary that shows the actual string. |
| |
| (lldb) frame info |
| frame #0: 0x000000010400cfea XUL`nsCSSParser::ParseProperty(this=0x00007fff5fbf5248, aPropID=eCSSProperty_margin_top, aPropValue=0x00007fff5fbf53f8, aSheetURI=0x0000000115ae8c00, aBaseURI=0x0000000115ae8c00, aSheetPrincipal=0x000000010ff9e040, aDeclaration=0x00000001826fd580, aChanged=0x00007fff5fbf5247, aIsImportant=false, aIsSVGMode=false) + 74 at nsCSSParser.cpp:12851 |
| (lldb) p aPropValue |
| (const nsAString_internal) $16 = u"-25px" |
| |
| (lldb) p this |
| (nsHTMLDocument *) $18 = 0x0000000115b56000 |
| (lldb) p mContentType |
| (nsCString) $19 = { |
| nsACString_internal = "text/html" |
| } |
| |
| * nscolor |
| |
| nscolors (32-bit RGBA colors) have a type summary that shows the color as |
| one of the CSS 2.1 color keywords, a six digit hex color, an rgba() color, |
| or the "transparent" keyword. |
| |
| (lldb) p this |
| (nsTextFrame *) $0 = 0x00000001168245e0 |
| (lldb) p *this->StyleColor() |
| (const nsStyleColor) $1 = { |
| mColor = lime |
| } |
| (lldb) expr -R -- *this->StyleColor() |
| (const nsStyleColor) $2 = { |
| mColor = 4278255360 |
| } |
| |
| * nsIAtom |
| |
| Atoms have a type summary that shows the string value inside the atom. |
| |
| (lldb) frame info |
| frame #0: 0x00000001028b8c49 XUL`mozilla::dom::Element::GetBoolAttr(this=0x0000000115ca1c50, aAttr=0x000000011012a640) const + 25 at Element.h:907 |
| (lldb) p aAttr |
| (PermanentAtomImpl *) $1 = 0x000000011012a640 u"readonly" |
| |
| * nsTArray and friends |
| |
| nsTArrays and their auto and fallible varieties have synthetic children |
| for their elements. This means when displaying them with "expr" (or "p"), |
| they will be shown like regular arrays, rather than showing the mHdr and |
| other fields. |
| |
| (lldb) frame info |
| frame #0: 0x00000001043eb8a8 XUL`SVGTextFrame::DoGlyphPositioning(this=0x000000012f3f8778) + 248 at SVGTextFrame.cpp:4940 |
| (lldb) p charPositions |
| (nsTArray<nsPoint>) $5 = { |
| [0] = { |
| mozilla::gfx::BasePoint<int, nsPoint> = { |
| x = 0 |
| y = 816 |
| } |
| } |
| [1] = { |
| mozilla::gfx::BasePoint<int, nsPoint> = { |
| x = 426 |
| y = 816 |
| } |
| } |
| [2] = { |
| mozilla::gfx::BasePoint<int, nsPoint> = { |
| x = 906 |
| y = 816 |
| } |
| } |
| } |
| (lldb) expr -R -- charPositions |
| (nsTArray<nsPoint>) $4 = { |
| nsTArray_Impl<nsPoint, nsTArrayInfallibleAllocator> = { |
| nsTArray_base<nsTArrayInfallibleAllocator, nsTArray_CopyWithMemutils> = { |
| mHdr = 0x000000012f3f1b80 |
| } |
| } |
| } |
| |
| * nsTextNode, nsTextFragment |
| |
| Text nodes have a type summary that shows the nsTextFragment in the |
| nsTextNode, which itself has a type summary that shows the text |
| content. |
| |
| (lldb) p this |
| (nsTextFrame *) $14 = 0x000000011811bb10 |
| (lldb) p mContent |
| (nsTextNode *) $15 = 0x0000000118130110 "Search or enter address" |
| |
