Bug 909972 - Avoid unnecessary GCs in asm.js compilation; r=luke

--HG--
extra : rebase_source : 41a55a9f837016efbcf013f9b51e9f5f5c48f28b

js/src/jit/AsmJS.cpp

@@ -1231,6 +1231,7 @@ class MOZ_STACK_CLASS ModuleCompiler
 
     char *                         errorString_;
     uint32_t                       errorOffset_;
+    bool                           errorOverRecursed_;
 
     int64_t                        usecBefore_;
     SlowFunctionVector             slowFunctions_;
@@ -1260,6 +1261,7 @@ class MOZ_STACK_CLASS ModuleCompiler
         globalAccesses_(cx),
         errorString_(nullptr),
         errorOffset_(UINT32_MAX),
+        errorOverRecursed_(false),
         usecBefore_(PRMJ_Now()),
         slowFunctions_(cx),
         finishedFunctionBodies_(false)
@@ -1275,6 +1277,8 @@ class MOZ_STACK_CLASS ModuleCompiler
                                                  errorString_);
             js_free(errorString_);
         }
+        if (errorOverRecursed_)
+            js_ReportOverRecursed(cx_);
 
         // Avoid spurious Label assertions on compilation failure.
         if (!stackOverflowLabel_.bound())
@@ -1324,7 +1328,15 @@ class MOZ_STACK_CLASS ModuleCompiler
     }
 
     bool fail(ParseNode *pn, const char *str) {
-        return failOffset(pn ? pn->pn_pos.begin : parser_.tokenStream.peekTokenPos().begin, str);
+        if (pn)
+            return failOffset(pn->pn_pos.begin, str);
+
+        // The exact rooting static analysis does not perform dataflow analysis, so it believes
+        // that unrooted things on the stack during compilation may still be accessed after this.
+        // Since pn is typically only null under OOM, this suppression simply forces any GC to be
+        // delayed until the compilation is off the stack and more memory can be freed.
+        gc::AutoSuppressGC nogc(cx_);
+        return failOffset(parser_.tokenStream.peekTokenPos().begin, str);
     }
 
     bool failfVA(ParseNode *pn, const char *fmt, va_list ap) {
@@ -1353,6 +1365,11 @@ class MOZ_STACK_CLASS ModuleCompiler
         return false;
     }
 
+    bool failOverRecursed() {
+        errorOverRecursed_ = true;
+        return false;
+    }
+
     static const unsigned SLOW_FUNCTION_THRESHOLD_MS = 250;
 
     bool maybeReportCompileTime(const Func &func) {
@@ -3813,7 +3830,7 @@ CheckMathBuiltinCall(FunctionCompiler &f, ParseNode *callNode, AsmJSMathBuiltin
 static bool
 CheckCall(FunctionCompiler &f, ParseNode *call, RetType retType, MDefinition **def, Type *type)
 {
-    JS_CHECK_RECURSION(f.cx(), return false);
+    JS_CHECK_RECURSION_DONT_REPORT(f.cx(), return f.m().failOverRecursed());
 
     ParseNode *callee = CallCallee(call);
 
@@ -4104,7 +4121,7 @@ static bool
 CheckAddOrSub(FunctionCompiler &f, ParseNode *expr, MDefinition **def, Type *type,
               unsigned *numAddOrSubOut = nullptr)
 {
-    JS_CHECK_RECURSION(f.cx(), return false);
+    JS_CHECK_RECURSION_DONT_REPORT(f.cx(), return f.m().failOverRecursed());
 
     JS_ASSERT(expr->isKind(PNK_ADD) || expr->isKind(PNK_SUB));
     ParseNode *lhs = BinaryLeft(expr);
@@ -4308,7 +4325,7 @@ CheckBitwise(FunctionCompiler &f, ParseNode *bitwise, MDefinition **def, Type *t
 static bool
 CheckExpr(FunctionCompiler &f, ParseNode *expr, MDefinition **def, Type *type)
 {
-    JS_CHECK_RECURSION(f.cx(), return false);
+    JS_CHECK_RECURSION_DONT_REPORT(f.cx(), return f.m().failOverRecursed());
 
     if (!f.mirGen().ensureBallast())
         return false;
@@ -4781,7 +4798,7 @@ CheckStatementList(FunctionCompiler &f, ParseNode *stmtList)
 static bool
 CheckStatement(FunctionCompiler &f, ParseNode *stmt, LabelVector *maybeLabels)
 {
-    JS_CHECK_RECURSION(f.cx(), return false);
+    JS_CHECK_RECURSION_DONT_REPORT(f.cx(), return f.m().failOverRecursed());
 
     if (!f.mirGen().ensureBallast())
         return false;

js/src/jsfriendapi.h

@@ -665,7 +665,7 @@ GetNativeStackLimit(JSContext *cx)
  * extra space so that we can ensure that crucial code is able to run.
  */
 
-#define JS_CHECK_RECURSION(cx, onerror)                              \
+#define JS_CHECK_RECURSION(cx, onerror)                                         \
     JS_BEGIN_MACRO                                                              \
         int stackDummy_;                                                        \
         if (!JS_CHECK_STACK_SIZE(js::GetNativeStackLimit(cx), &stackDummy_)) {  \
@@ -674,6 +674,14 @@ GetNativeStackLimit(JSContext *cx)
         }                                                                       \
     JS_END_MACRO
 
+#define JS_CHECK_RECURSION_DONT_REPORT(cx, onerror)                             \
+    JS_BEGIN_MACRO                                                              \
+        int stackDummy_;                                                        \
+        if (!JS_CHECK_STACK_SIZE(js::GetNativeStackLimit(cx), &stackDummy_)) {  \
+            onerror;                                                            \
+        }                                                                       \
+    JS_END_MACRO
+
 #define JS_CHECK_RECURSION_WITH_SP_DONT_REPORT(cx, sp, onerror)                 \
     JS_BEGIN_MACRO                                                              \
         if (!JS_CHECK_STACK_SIZE(js::GetNativeStackLimit(cx), sp)) {            \