Bug 1499507 - Don't collect line numbers for profiling stack frames. r=njn

They were not displayed in the UI, and the instructions to initialize the line
field of a stack frame increased code size unnecessarily.

This change reduces the binary size on Linux x64 by around 100KB.

Here's a diff of the impact on the code generated for Attr_Binding::get_specified
in the Mac build:

@@ -20,17 +20,16 @@
    movq       0x8(%rbx), %rax
    movq       %r12, %rcx
    shlq       $0x5, %rcx
    leaq       aGetAttrspecifi, %rdx                       ; "get Attr.specified"
    movq       %rdx, (%rax,%rcx)
    movq       $0x0, 0x8(%rax,%rcx)
    leaq       -40(%rbp), %rdx
    movq       %rdx, 0x10(%rax,%rcx)
-   movl       $0x106, 0x18(%rax,%rcx)
    movl       $0x1c, 0x1c(%rax,%rcx)
    leal       0x1(%r12), %eax
    movl       %eax, 0x10(%rbx)

    movq       %r15, %rdi
    call       __ZNK7mozilla3dom4Attr9SpecifiedEv          ; mozilla::dom::Attr::Specified() const
    movzxl     %al, %eax
    movabsq    $0xfff9000000000000, %rcx

Depends on D9193

Differential Revision: https://phabricator.services.mozilla.com/D9195

--HG--
extra : moz-landing-system : lando

dom/base/nsJSUtils.cpp

@@ -125,7 +125,7 @@ nsJSUtils::ExecutionContext::ExecutionContext(JSContext* aCx,
   :
 #ifdef MOZ_GECKO_PROFILER
     mAutoProfilerLabel("nsJSUtils::ExecutionContext", /* dynamicStr */ nullptr,
-                       __LINE__, js::ProfilingStackFrame::Category::JS),
+                       js::ProfilingStackFrame::Category::JS),
 #endif
     mCx(aCx)
   , mRealm(aCx, aGlobal)

dom/script/ScriptSettings.cpp

@@ -645,7 +645,7 @@ AutoEntryScript::AutoEntryScript(nsIGlobalObject* aGlobalObject,
   // ran.
   , mCallerOverride(cx())
 #ifdef MOZ_GECKO_PROFILER
-  , mAutoProfilerLabel("AutoEntryScript", aReason, __LINE__,
+  , mAutoProfilerLabel("AutoEntryScript", aReason,
                        js::ProfilingStackFrame::Category::JS)
 #endif
 {

js/public/ProfilingStack.h

@@ -145,9 +145,12 @@ class ProfilingStackFrame
     mozilla::Atomic<void*, mozilla::ReleaseAcquire,
                     mozilla::recordreplay::Behavior::DontPreserve> spOrScript;
 
-    // Line number for non-JS stack frames, the bytecode offset otherwise.
+    // The bytecode offset for JS stack frames.
+    // Must not be used on non-JS frames; it'll contain either the default 0,
+    // or a leftover value from a previous JS stack frame that was using this
+    // ProfilingStackFrame object.
     mozilla::Atomic<int32_t, mozilla::ReleaseAcquire,
-                    mozilla::recordreplay::Behavior::DontPreserve> lineOrPcOffset;
+                    mozilla::recordreplay::Behavior::DontPreserve> pcOffsetIfJS_;
 
     // Bits 0...1 hold the Kind. Bits 2...31 hold the category.
     mozilla::Atomic<uint32_t, mozilla::ReleaseAcquire,
@@ -163,8 +166,8 @@ class ProfilingStackFrame
         dynamicString_ = other.dynamicString();
         void* spScript = other.spOrScript;
         spOrScript = spScript;
-        int32_t offset = other.lineOrPcOffset;
+        int32_t offsetIfJS = other.pcOffsetIfJS_;
-        lineOrPcOffset = offset;
+        pcOffsetIfJS_ = offsetIfJS;
         uint32_t kindAndCategory = other.kindAndCategory_;
         kindAndCategory_ = kindAndCategory;
         return *this;
@@ -233,12 +236,12 @@ class ProfilingStackFrame
     const char* dynamicString() const { return dynamicString_; }
 
     void initLabelFrame(const char* aLabel, const char* aDynamicString, void* sp,
-                        uint32_t aLine, Category aCategory)
+                        Category aCategory)
     {
         label_ = aLabel;
         dynamicString_ = aDynamicString;
         spOrScript = sp;
-        lineOrPcOffset = static_cast<int32_t>(aLine);
+        // pcOffsetIfJS_ is not set and must not be used on label frames.
         kindAndCategory_ = uint32_t(Kind::LABEL) | (uint32_t(aCategory) << uint32_t(Kind::KIND_BITCOUNT));
         MOZ_ASSERT(isLabelFrame());
     }
@@ -248,7 +251,7 @@ class ProfilingStackFrame
         label_ = "";
         dynamicString_ = nullptr;
         spOrScript = sp;
-        lineOrPcOffset = 0;
+        // pcOffsetIfJS_ is not set and must not be used on sp marker frames.
         kindAndCategory_ = uint32_t(Kind::SP_MARKER) | (uint32_t(Category::OTHER) << uint32_t(Kind::KIND_BITCOUNT));
         MOZ_ASSERT(isSpMarkerFrame());
     }
@@ -259,7 +262,7 @@ class ProfilingStackFrame
         label_ = aLabel;
         dynamicString_ = aDynamicString;
         spOrScript = aScript;
-        lineOrPcOffset = pcToOffset(aScript, aPc);
+        pcOffsetIfJS_ = pcToOffset(aScript, aPc);
         kindAndCategory_ = uint32_t(Kind::JS_NORMAL) | (uint32_t(Category::JS) << uint32_t(Kind::KIND_BITCOUNT));
         MOZ_ASSERT(isJsFrame());
     }
@@ -283,11 +286,6 @@ class ProfilingStackFrame
 
     JS_PUBLIC_API(JSScript*) script() const;
 
-    uint32_t line() const {
-        MOZ_ASSERT(!isJsFrame());
-        return static_cast<uint32_t>(lineOrPcOffset);
-    }
-
     // Note that the pointer returned might be invalid.
     JSScript* rawScript() const {
         MOZ_ASSERT(isJsFrame());
@@ -363,13 +361,13 @@ class ProfilingStack final
     ~ProfilingStack();
 
     void pushLabelFrame(const char* label, const char* dynamicString, void* sp,
-                        uint32_t line, js::ProfilingStackFrame::Category category) {
+                        js::ProfilingStackFrame::Category category) {
         uint32_t oldStackPointer = stackPointer;
 
         if (MOZ_UNLIKELY(oldStackPointer >= capacity)) {
             ensureCapacitySlow();
         }
-        frames[oldStackPointer].initLabelFrame(label, dynamicString, sp, line, category);
+        frames[oldStackPointer].initLabelFrame(label, dynamicString, sp, category);
 
         // This must happen at the end! The compiler will not reorder this
         // update because stackPointer is Atomic<..., ReleaseAcquire>, so any

js/src/vm/GeckoProfiler-inl.h

@@ -98,7 +98,6 @@ AutoGeckoProfilerEntry::AutoGeckoProfilerEntry(JSContext* cx, const char* label,
     profiler_->profilingStack_->pushLabelFrame(label,
                                             /* dynamicString = */ nullptr,
                                             /* sp = */ this,
-                                            /* line = */ 0,
                                             category);
 }
 

js/src/vm/GeckoProfiler.cpp

@@ -256,7 +256,7 @@ GeckoProfilerThread::exit(JSScript* script, JSFunction* maybeFun)
                 if (frame.isJsFrame()) {
                     fprintf(stderr, "  [%d] JS %s\n", i, frame.dynamicString());
                 } else {
-                    fprintf(stderr, "  [%d] C line %d %s\n", i, frame.line(), frame.dynamicString());
+                    fprintf(stderr, "  [%d] Label %s\n", i, frame.dynamicString());
                 }
             }
         }
@@ -449,12 +449,12 @@ JS_FRIEND_API(jsbytecode*)
 ProfilingStackFrame::pc() const
 {
     MOZ_ASSERT(isJsFrame());
-    if (lineOrPcOffset == NullPCOffset) {
+    if (pcOffsetIfJS_ == NullPCOffset) {
         return nullptr;
     }
 
     JSScript* script = this->script();
-    return script ? script->offsetToPC(lineOrPcOffset) : nullptr;
+    return script ? script->offsetToPC(pcOffsetIfJS_) : nullptr;
 }
 
 /* static */ int32_t
@@ -468,7 +468,7 @@ ProfilingStackFrame::setPC(jsbytecode* pc)
     MOZ_ASSERT(isJsFrame());
     JSScript* script = this->script();
     MOZ_ASSERT(script); // This should not be called while profiling is suppressed.
-    lineOrPcOffset = pcToOffset(script, pc);
+    pcOffsetIfJS_ = pcToOffset(script, pc);
 }
 
 JS_FRIEND_API(void)

js/src/vm/HelperThreads.cpp

@@ -56,7 +56,7 @@ GlobalHelperThreadState* gHelperThreadState = nullptr;
 #define PROFILER_RAII_EXPAND(id, line) PROFILER_RAII_PASTE(id, line)
 #define PROFILER_RAII PROFILER_RAII_EXPAND(raiiObject, __LINE__)
 #define AUTO_PROFILER_LABEL(label, category) \
-  HelperThread::AutoProfilerLabel PROFILER_RAII(this, label, __LINE__, \
+  HelperThread::AutoProfilerLabel PROFILER_RAII(this, label, \
                                                 js::ProfilingStackFrame::Category::category)
 
 bool
@@ -2583,12 +2583,11 @@ const HelperThread::TaskSpec HelperThread::taskSpecs[] = {
 
 HelperThread::AutoProfilerLabel::AutoProfilerLabel(HelperThread* helperThread,
                                                    const char* label,
-                                                   uint32_t line,
                                                    ProfilingStackFrame::Category category)
   : profilingStack(helperThread->profilingStack)
 {
     if (profilingStack) {
-        profilingStack->pushLabelFrame(label, nullptr, this, line, category);
+        profilingStack->pushLabelFrame(label, nullptr, this, category);
     }
 }
 

js/src/vm/HelperThreads.h

@@ -421,7 +421,6 @@ struct HelperThread
     struct AutoProfilerLabel
     {
         AutoProfilerLabel(HelperThread* helperThread, const char* label,
-                          uint32_t line,
                           ProfilingStackFrame::Category category);
         ~AutoProfilerLabel();
 

mozglue/build/WindowsDllBlocklist.cpp

@@ -669,8 +669,7 @@ continue_loading:
   // A few DLLs such as xul.dll and nss3.dll get loaded before mozglue's
   // AutoProfilerLabel is initialized, and this is a no-op in those cases. But
   // the vast majority of DLLs do get labelled here.
-  AutoProfilerLabel label("WindowsDllBlocklist::patched_LdrLoadDll", dllName,
+  AutoProfilerLabel label("WindowsDllBlocklist::patched_LdrLoadDll", dllName);
-                          __LINE__);
 
 #ifdef _M_AMD64
   // Prevent the stack walker from suspending this thread when LdrLoadDll

mozglue/misc/AutoProfilerLabel.cpp

@@ -20,13 +20,12 @@ RegisterProfilerLabelEnterExit(ProfilerLabelEnter aEnter,
 }
 
 AutoProfilerLabel::AutoProfilerLabel(const char* aLabel,
-                                     const char* aDynamicString,
+                                     const char* aDynamicString
-                                     uint32_t aLine
                                      MOZ_GUARD_OBJECT_NOTIFIER_PARAM_IN_IMPL)
 {
   MOZ_GUARD_OBJECT_NOTIFIER_INIT;
 
-  mProfilingStack = sEnter ? sEnter(aLabel, aDynamicString, this, aLine) : nullptr;
+  mProfilingStack = sEnter ? sEnter(aLabel, aDynamicString, this) : nullptr;
 }
 
 AutoProfilerLabel::~AutoProfilerLabel()

mozglue/misc/AutoProfilerLabel.h

@@ -29,8 +29,7 @@ class ProfilingStack;
 
 namespace mozilla {
 
-typedef ProfilingStack* (*ProfilerLabelEnter)(const char*, const char*, void*,
+typedef ProfilingStack* (*ProfilerLabelEnter)(const char*, const char*, void*);
-                                           uint32_t);
 typedef void (*ProfilerLabelExit)(ProfilingStack*);
 
 // Register callbacks that do the entry/exit work involving sProfilingStack.
@@ -44,8 +43,7 @@ MFBT_API void RegisterProfilerLabelEnterExit(ProfilerLabelEnter aEnter,
 class MOZ_RAII AutoProfilerLabel
 {
 public:
-  AutoProfilerLabel(const char* aLabel, const char* aDynamicString,
+  AutoProfilerLabel(const char* aLabel, const char* aDynamicString
-                    uint32_t aLine
                     MOZ_GUARD_OBJECT_NOTIFIER_PARAM);
   ~AutoProfilerLabel();
 

tools/profiler/core/ProfileBuffer.cpp

@@ -198,7 +198,6 @@ ProfileBufferCollector::CollectProfilingStackFrame(const js::ProfilingStackFrame
     }
   } else {
     MOZ_ASSERT(aFrame.isLabelFrame());
-    line = Some(aFrame.line());
   }
 
   if (dynamicString) {

tools/profiler/core/platform.cpp

@@ -2493,12 +2493,11 @@ locked_profiler_start(PSLockRef aLock, uint32_t aCapacity, double aInterval,
 
 // This basically duplicates AutoProfilerLabel's constructor.
 ProfilingStack*
-MozGlueLabelEnter(const char* aLabel, const char* aDynamicString, void* aSp,
+MozGlueLabelEnter(const char* aLabel, const char* aDynamicString, void* aSp)
-                  uint32_t aLine)
 {
   ProfilingStack* profilingStack = AutoProfilerLabel::sProfilingStack.get();
   if (profilingStack) {
-    profilingStack->pushLabelFrame(aLabel, aDynamicString, aSp, aLine,
+    profilingStack->pushLabelFrame(aLabel, aDynamicString, aSp,
                                 js::ProfilingStackFrame::Category::OTHER);
   }
   return profilingStack;

tools/profiler/public/GeckoProfiler.h

@@ -473,7 +473,7 @@ mozilla::Maybe<ProfilerBufferInfo> profiler_get_buffer_info();
 // Use AUTO_PROFILER_LABEL_DYNAMIC_* if you want to add additional / dynamic
 // information to the label stack frame.
 #define AUTO_PROFILER_LABEL(label, category) \
-  mozilla::AutoProfilerLabel PROFILER_RAII(label, nullptr, __LINE__, \
+  mozilla::AutoProfilerLabel PROFILER_RAII(label, nullptr, \
                                            js::ProfilingStackFrame::Category::category)
 
 // Similar to AUTO_PROFILER_LABEL, but with an additional string. The inserted
@@ -497,7 +497,7 @@ mozilla::Maybe<ProfilerBufferInfo> profiler_get_buffer_info();
 // the profile buffer than AUTO_PROFILER_LABEL_DYNAMIC_* frames.
 #define AUTO_PROFILER_LABEL_DYNAMIC_CSTR(label, category, cStr) \
   mozilla::AutoProfilerLabel \
-    PROFILER_RAII(label, cStr, __LINE__, js::ProfilingStackFrame::Category::category)
+    PROFILER_RAII(label, cStr, js::ProfilingStackFrame::Category::category)
 
 // Similar to AUTO_PROFILER_LABEL_DYNAMIC_CSTR, but takes an nsACString.
 //
@@ -511,7 +511,7 @@ mozilla::Maybe<ProfilerBufferInfo> profiler_get_buffer_info();
   mozilla::Maybe<AutoProfilerLabel> raiiObjectNsCString; \
   if (profiler_is_active()) { \
     autoCStr.emplace(nsCStr); \
-    raiiObjectNsCString.emplace(label, autoCStr->get(), __LINE__, \
+    raiiObjectNsCString.emplace(label, autoCStr->get(), \
                                 js::ProfilingStackFrame::Category::category); \
   }
 
@@ -528,7 +528,7 @@ mozilla::Maybe<ProfilerBufferInfo> profiler_get_buffer_info();
   mozilla::Maybe<AutoProfilerLabel> raiiObjectLossyNsString; \
   if (profiler_is_active()) { \
     asciiStr.emplace(nsStr); \
-    raiiObjectLossyNsString.emplace(label, asciiStr->get(), __LINE__, \
+    raiiObjectLossyNsString.emplace(label, asciiStr->get(), \
                                     js::ProfilingStackFrame::Category::category); \
   }
 
@@ -539,7 +539,7 @@ mozilla::Maybe<ProfilerBufferInfo> profiler_get_buffer_info();
 // ProfilingStack from the JS context, and avoids almost all overhead in the case
 // where the profiler is disabled.
 #define AUTO_PROFILER_LABEL_FAST(label, category, ctx) \
-  mozilla::AutoProfilerLabel PROFILER_RAII(ctx, label, nullptr, __LINE__, \
+  mozilla::AutoProfilerLabel PROFILER_RAII(ctx, label, nullptr, \
                                            js::ProfilingStackFrame::Category::category)
 
 // Insert a marker in the profile timeline. This is useful to delimit something
@@ -719,37 +719,36 @@ class MOZ_RAII AutoProfilerLabel
 public:
   // This is the AUTO_PROFILER_LABEL and AUTO_PROFILER_LABEL_DYNAMIC variant.
   AutoProfilerLabel(const char* aLabel, const char* aDynamicString,
-                    uint32_t aLine, js::ProfilingStackFrame::Category aCategory
+                    js::ProfilingStackFrame::Category aCategory
                     MOZ_GUARD_OBJECT_NOTIFIER_PARAM)
   {
     MOZ_GUARD_OBJECT_NOTIFIER_INIT;
 
     // Get the ProfilingStack from TLS.
-    Push(sProfilingStack.get(), aLabel, aDynamicString, aLine, aCategory);
+    Push(sProfilingStack.get(), aLabel, aDynamicString, aCategory);
   }
 
   // This is the AUTO_PROFILER_LABEL_FAST variant. It retrieves the ProfilingStack
   // from the JSContext and does nothing if the profiler is inactive.
   AutoProfilerLabel(JSContext* aJSContext,
                     const char* aLabel, const char* aDynamicString,
-                    uint32_t aLine, js::ProfilingStackFrame::Category aCategory
+                    js::ProfilingStackFrame::Category aCategory
                     MOZ_GUARD_OBJECT_NOTIFIER_PARAM)
   {
     MOZ_GUARD_OBJECT_NOTIFIER_INIT;
     Push(js::GetContextProfilingStackIfEnabled(aJSContext),
-         aLabel, aDynamicString, aLine, aCategory);
+         aLabel, aDynamicString, aCategory);
   }
 
   void Push(ProfilingStack* aProfilingStack,
             const char* aLabel, const char* aDynamicString,
-            uint32_t aLine, js::ProfilingStackFrame::Category aCategory)
+            js::ProfilingStackFrame::Category aCategory)
   {
     // This function runs both on and off the main thread.
 
     mProfilingStack = aProfilingStack;
     if (mProfilingStack) {
-      mProfilingStack->pushLabelFrame(aLabel, aDynamicString, this, aLine,
+      mProfilingStack->pushLabelFrame(aLabel, aDynamicString, this, aCategory);
-                                   aCategory);
     }
   }
 

tools/profiler/tests/gtest/GeckoProfiler.cpp

@@ -748,9 +748,9 @@ TEST(GeckoProfiler, ProfilingStack)
     ASSERT_TRUE(profiler_get_backtrace());
   }
 
-  AutoProfilerLabel label1("A", nullptr, 888,
+  AutoProfilerLabel label1("A", nullptr,
                            js::ProfilingStackFrame::Category::DOM);
-  AutoProfilerLabel label2("A", dynamic.get(), 888,
+  AutoProfilerLabel label2("A", dynamic.get(),
                            js::ProfilingStackFrame::Category::NETWORK);
   ASSERT_TRUE(profiler_get_backtrace());