Bug 600016 - TM: Recognize that the result of Math.floor is an integer (r=nnethercote)

js/src/jsmath.cpp

@@ -248,8 +248,8 @@ math_atan2(JSContext *cx, uintN argc, Value *vp)
     return JS_TRUE;
 }
 
-static inline jsdouble JS_FASTCALL
-math_ceil_kernel(jsdouble x)
+jsdouble
+js_math_ceil_impl(jsdouble x)
 {
 #ifdef __APPLE__
     if (x < 0 && x > -1.0)
@@ -269,7 +269,7 @@ js_math_ceil(JSContext *cx, uintN argc, Value *vp)
     }
     if (!ValueToNumber(cx, vp[2], &x))
         return JS_FALSE;
-    z = math_ceil_kernel(x);
+    z = js_math_ceil_impl(x);
     vp->setNumber(z);
     return JS_TRUE;
 }
@@ -326,6 +326,12 @@ math_exp(JSContext *cx, uintN argc, Value *vp)
     return JS_TRUE;
 }
 
+jsdouble
+js_math_floor_impl(jsdouble x)
+{
+    return floor(x);
+}
+
 JSBool
 js_math_floor(JSContext *cx, uintN argc, Value *vp)
 {
@@ -337,7 +343,7 @@ js_math_floor(JSContext *cx, uintN argc, Value *vp)
     }
     if (!ValueToNumber(cx, vp[2], &x))
         return JS_FALSE;
-    z = floor(x);
+    z = js_math_floor_impl(x);
     vp->setNumber(z);
     return JS_TRUE;
 }
@@ -573,6 +579,12 @@ js_copysign(double x, double y)
 }
 #endif
 
+jsdouble
+js_math_round_impl(jsdouble x)
+{
+    return js_copysign(floor(x + 0.5), x);
+}
+
 JSBool
 js_math_round(JSContext *cx, uintN argc, Value *vp)
 {
@@ -777,19 +789,19 @@ math_random_tn(JSContext *cx)
 static jsdouble FASTCALL
 math_round_tn(jsdouble x)
 {
-    return js_copysign(floor(x + 0.5), x);
+    return js_math_round_impl(x);
 }
 
 static jsdouble FASTCALL
 math_ceil_tn(jsdouble x)
 {
-    return math_ceil_kernel(x);
+    return js_math_ceil_impl(x);
 }
 
 static jsdouble FASTCALL
 math_floor_tn(jsdouble x)
 {
-    return floor(x);
+    return js_math_floor_impl(x);
 }
 
 JS_DEFINE_TRCINFO_1(math_acos,

js/src/jsmath.h

@@ -105,4 +105,13 @@ js_math_min(JSContext *cx, uintN argc, js::Value *vp);
 extern JSBool
 js_math_round(JSContext *cx, uintN argc, js::Value *vp);
 
+extern jsdouble
+js_math_ceil_impl(jsdouble x);
+
+extern jsdouble
+js_math_floor_impl(jsdouble x);
+
+extern jsdouble
+js_math_round_impl(jsdouble x);
+
 #endif /* jsmath_h___ */

js/src/jstracer.cpp

@@ -11337,6 +11337,50 @@ next_specialization:;
     return RECORD_STOP;
 }
 
+static JSBool FASTCALL
+ceilReturningInt(jsdouble x, int32 *out)
+{
+    jsdouble r = js_math_ceil_impl(x);
+    return JSDOUBLE_IS_INT32(r, out);
+}
+
+static JSBool FASTCALL
+floorReturningInt(jsdouble x, int32 *out)
+{
+    jsdouble r = js_math_floor_impl(x);
+    return JSDOUBLE_IS_INT32(r, out);
+}
+
+static JSBool FASTCALL
+roundReturningInt(jsdouble x, int32 *out)
+{
+    jsdouble r = js_math_round_impl(x);
+    return JSDOUBLE_IS_INT32(r, out);
+}
+
+JS_DEFINE_CALLINFO_2(static, BOOL, ceilReturningInt, DOUBLE, INT32PTR, 1, ACCSET_NONE)
+JS_DEFINE_CALLINFO_2(static, BOOL, floorReturningInt, DOUBLE, INT32PTR, 1, ACCSET_NONE)
+JS_DEFINE_CALLINFO_2(static, BOOL, roundReturningInt, DOUBLE, INT32PTR, 1, ACCSET_NONE)
+
+JS_REQUIRES_STACK RecordingStatus
+TraceRecorder::callFloatReturningInt(uintN argc, const nanojit::CallInfo *ci)
+{
+    Value& arg = stackval(-1);
+    LIns* resptr_ins = lir->insAlloc(sizeof(int32));
+    LIns* args[] = { resptr_ins, get(&arg) };
+    LIns* fits_ins = lir->insCall(ci, args);
+
+    guard(false, lir->insEqI_0(fits_ins), OVERFLOW_EXIT);
+
+    LIns* res_ins = lir->insLoad(LIR_ldi, resptr_ins, 0, ACCSET_ALLOC);
+
+    set(&stackval(0 - (2 + argc)), lir->ins1(LIR_i2d, res_ins));
+
+    pendingSpecializedNative = IGNORE_NATIVE_CALL_COMPLETE_CALLBACK;
+
+    return RECORD_CONTINUE;
+}
+
 JS_REQUIRES_STACK RecordingStatus
 TraceRecorder::callNative(uintN argc, JSOp mode)
 {
@@ -11354,11 +11398,22 @@ TraceRecorder::callNative(uintN argc, JSOp mode)
         if (vp[2].isNumber() && mode == JSOP_CALL) {
             if (native == js_math_ceil || native == js_math_floor || native == js_math_round) {
                 LIns* a = get(&vp[2]);
+                int32 result;
                 if (isPromote(a)) {
                     set(&vp[0], a);
                     pendingSpecializedNative = IGNORE_NATIVE_CALL_COMPLETE_CALLBACK;
                     return RECORD_CONTINUE;
                 }
+                if (native == js_math_floor) {
+                    if (floorReturningInt(vp[2].toNumber(), &result))
+                        return callFloatReturningInt(argc, &floorReturningInt_ci);
+                } else if (native == js_math_ceil) {
+                    if (ceilReturningInt(vp[2].toNumber(), &result))
+                        return callFloatReturningInt(argc, &ceilReturningInt_ci);
+                } else if (native == js_math_round) {
+                    if (roundReturningInt(vp[2].toNumber(), &result))
+                        return callFloatReturningInt(argc, &roundReturningInt_ci);
+                }
             }
             if (vp[1].isString()) {
                 JSString *str = vp[1].toString();

js/src/jstracer.h

@@ -1356,6 +1356,8 @@ class TraceRecorder
     JS_REQUIRES_STACK RecordingStatus callSpecializedNative(JSNativeTraceInfo* trcinfo, uintN argc,
                                                               bool constructing);
     JS_REQUIRES_STACK RecordingStatus callNative(uintN argc, JSOp mode);
+    JS_REQUIRES_STACK RecordingStatus callFloatReturningInt(uintN argc,
+                                                            const nanojit::CallInfo *ci);
     JS_REQUIRES_STACK RecordingStatus functionCall(uintN argc, JSOp mode);
 
     JS_REQUIRES_STACK void trackCfgMerges(jsbytecode* pc);