From 6dc231866c298e2eee7f7b778fad8867d0f9e1b2 Mon Sep 17 00:00:00 2001
From: Cameron Kaiser <classilla@floodgap.com>
Date: Thu, 5 Mar 2020 19:17:10 -0800
Subject: [PATCH] #593: M1608256 (disable optimization)

---
 js/src/jit/Ion.cpp         |  8 --------
 js/src/jit/IonAnalysis.cpp |  4 ++++
 js/src/jit/Lowering.cpp    | 11 +++--------
 3 files changed, 7 insertions(+), 16 deletions(-)

diff --git a/js/src/jit/Ion.cpp b/js/src/jit/Ion.cpp
index caf8a3602..506153ffc 100644
--- a/js/src/jit/Ion.cpp
+++ b/js/src/jit/Ion.cpp
@@ -1509,14 +1509,6 @@ OptimizeMIR(MIRGenerator* mir)
     if (mir->shouldCancel("Start"))
         return false;
 
-    if (!mir->compilingAsmJS()) {
-        if (!MakeMRegExpHoistable(mir, graph))
-            return false;
-
-        if (mir->shouldCancel("Make MRegExp Hoistable"))
-            return false;
-    }
-
     gs.spewPass("BuildSSA");
     AssertBasicGraphCoherency(graph);
 
diff --git a/js/src/jit/IonAnalysis.cpp b/js/src/jit/IonAnalysis.cpp
index bc889ad95..77cc56763 100644
--- a/js/src/jit/IonAnalysis.cpp
+++ b/js/src/jit/IonAnalysis.cpp
@@ -1878,6 +1878,9 @@ jit::ApplyTypeInformation(MIRGenerator* mir, MIRGraph& graph)
 bool
 jit::MakeMRegExpHoistable(MIRGenerator* mir, MIRGraph& graph)
 {
+    MOZ_CRASH("thou may not hoist this regex");
+    return false;
+#if(0)
     // If we are compiling try blocks, regular expressions may be observable
     // from catch blocks (which Ion does not compile). For now just disable the
     // pass in this case.
@@ -1945,6 +1948,7 @@ jit::MakeMRegExpHoistable(MIRGenerator* mir, MIRGraph& graph)
     }
 
     return true;
+#endif
 }
 
 bool
diff --git a/js/src/jit/Lowering.cpp b/js/src/jit/Lowering.cpp
index cadb46803..57d25bae8 100644
--- a/js/src/jit/Lowering.cpp
+++ b/js/src/jit/Lowering.cpp
@@ -2099,14 +2099,9 @@ MustCloneRegExp(MRegExp* regexp)
 void
 LIRGenerator::visitRegExp(MRegExp* ins)
 {
-    if (!MustCloneRegExp(ins)) {
-        RegExpObject* source = ins->source();
-        define(new(alloc()) LPointer(source), ins);
-    } else {
-        LRegExp* lir = new(alloc()) LRegExp();
-        defineReturn(lir, ins);
-        assignSafepoint(lir, ins);
-    }
+    LRegExp* lir = new(alloc()) LRegExp();
+    defineReturn(lir, ins);
+    assignSafepoint(lir, ins);
 }
 
 void