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| -rw-r--r-- | python/lldbutils/README.txt | 221 |
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diff --git a/python/lldbutils/README.txt b/python/lldbutils/README.txt new file mode 100644 index 0000000000..fd7e90675c --- /dev/null +++ b/python/lldbutils/README.txt @@ -0,0 +1,221 @@ +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} ink-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} ink-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} ink-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} ink-overflow=360,426,7980,1410 scr-overflow=480,480,7740,1236 < + Block(body)(1)@0x11687ebb0 {480,480,0,1236} ink-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} ink-overflow=-120,-54,7980,1410 scr-overflow=0,0,7740,1236 < + nsTextControlFrame@0x11687f068 {0,66,7740,1170} ink-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} ink-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) $16 = u"-25px" + + (lldb) p this + (nsHTMLDocument *) $18 = 0x0000000115b56000 + (lldb) p mContentType + (nsCString) $19 = { + nsACString = "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" + |