Bug 1338642 - Backout bug 1315596 (Don't evict bundles which won't help with allocating the target bundle), r=sunfish.

js/src/jit/BacktrackingAllocator.cpp

@@ -1389,29 +1389,6 @@ BacktrackingAllocator::computeRequirement(LiveBundle* bundle,
     return true;
 }
 
-// Return whether |conflicting| has any fixed uses of registers which overlap
-// with |bundle|.
-bool
-BacktrackingAllocator::hasFixedUseOverlap(LiveBundle* bundle, const LiveBundleVector& conflicting)
-{
-    for (size_t i = 0; i < conflicting.length(); i++) {
-        LiveBundle* existing = conflicting[i];
-        for (LiveRange::BundleLinkIterator iter = existing->rangesBegin(); iter; iter++) {
-            LiveRange* range = LiveRange::get(*iter);
-            if (range->hasDefinition()) {
-                LDefinition* def = vregs[range->vreg()].def();
-                if (def->policy() == LDefinition::FIXED && bundle->rangeFor(range->from()))
-                    return true;
-            }
-            for (UsePositionIterator iter(range->usesBegin()); iter; iter++) {
-                if (iter->usePolicy() == LUse::FIXED && bundle->rangeFor(iter->pos))
-                    return true;
-            }
-        }
-    }
-    return false;
-}
-
 bool
 BacktrackingAllocator::tryAllocateRegister(PhysicalRegister& r, LiveBundle* bundle,
                                            bool* success, bool* pfixed, LiveBundleVector& conflicting)
@@ -1479,12 +1456,7 @@ BacktrackingAllocator::tryAllocateRegister(PhysicalRegister& r, LiveBundle* bund
         }
 #endif
 
-        if (hasFixedUseOverlap(bundle, aliasedConflicting)) {
-            // Ignore conflicting bundles whose eviction will not allow the
-            // bundle to be allocated.
-            JitSpew(JitSpew_RegAlloc,
-                    "  Ignoring conflict due to fixed use/def overlap with bundle");
-        } else if (conflicting.empty()) {
+        if (conflicting.empty()) {
             if (!conflicting.appendAll(aliasedConflicting))
                 return false;
         } else {

js/src/jit/BacktrackingAllocator.h

@@ -715,7 +715,6 @@ class BacktrackingAllocator : protected RegisterAllocator
     MOZ_MUST_USE bool processBundle(MIRGenerator* mir, LiveBundle* bundle);
     MOZ_MUST_USE bool computeRequirement(LiveBundle* bundle, Requirement *prequirement,
                                          Requirement *phint);
-    bool hasFixedUseOverlap(LiveBundle* bundle, const LiveBundleVector& conflicting);
     MOZ_MUST_USE bool tryAllocateRegister(PhysicalRegister& r, LiveBundle* bundle, bool* success,
                                           bool* pfixed, LiveBundleVector& conflicting);
     MOZ_MUST_USE bool evictBundle(LiveBundle* bundle);