Index: llvm/trunk/lib/Transforms/Scalar/RewriteStatepointsForGC.cpp
===================================================================
--- llvm/trunk/lib/Transforms/Scalar/RewriteStatepointsForGC.cpp
+++ llvm/trunk/lib/Transforms/Scalar/RewriteStatepointsForGC.cpp
@@ -2452,6 +2452,37 @@
       FoldSingleEntryPHINodes(&BB);
     }
 
+  // Before we start introducing relocations, we want to tweak the IR a bit to
+  // avoid unfortunate code generation effects.  The main example is that we 
+  // want to try to make sure the comparison feeding a branch is after any
+  // safepoints.  Otherwise, we end up with a comparison of pre-relocation
+  // values feeding a branch after relocation.  This is semantically correct,
+  // but results in extra register pressure since both the pre-relocation and
+  // post-relocation copies must be available in registers.  For code without
+  // relocations this is handled elsewhere, but teaching the scheduler to
+  // reverse the transform we're about to do would be slightly complex.
+  // Note: This may extend the live range of the inputs to the icmp and thus
+  // increase the liveset of any statepoint we move over.  This is profitable
+  // as long as all statepoints are in rare blocks.  If we had in-register
+  // lowering for live values this would be a much safer transform.
+  auto getConditionInst = [](TerminatorInst *TI) -> Instruction* {
+    if (auto *BI = dyn_cast<BranchInst>(TI))
+      if (BI->isConditional())
+        return dyn_cast<Instruction>(BI->getCondition());
+    // TODO: Extend this to handle switches
+    return nullptr;
+  };
+  for (BasicBlock &BB : F) {
+    TerminatorInst *TI = BB.getTerminator();
+    if (auto *Cond = getConditionInst(TI))
+      // TODO: Handle more than just ICmps here.  We should be able to move
+      // most instructions without side effects or memory access.  
+      if (isa<ICmpInst>(Cond) && Cond->hasOneUse()) {
+        MadeChange = true;
+        Cond->moveBefore(TI);
+      }
+  }
+
   MadeChange |= insertParsePoints(F, DT, this, ParsePointNeeded);
   return MadeChange;
 }
Index: llvm/trunk/test/Transforms/RewriteStatepointsForGC/codegen-cond.ll
===================================================================
--- llvm/trunk/test/Transforms/RewriteStatepointsForGC/codegen-cond.ll
+++ llvm/trunk/test/Transforms/RewriteStatepointsForGC/codegen-cond.ll
@@ -0,0 +1,74 @@
+; RUN: opt -rewrite-statepoints-for-gc -S < %s | FileCheck %s
+
+; A null test of a single value
+define i1 @test(i8 addrspace(1)* %p, i1 %rare) gc "statepoint-example" {
+; CHECK-LABEL: @test
+entry:
+   %cond = icmp eq i8 addrspace(1)* %p, null
+   br i1 %rare, label %safepoint, label %continue, !prof !0
+safepoint:
+   call i32 (i64, i32, void ()*, i32, i32, ...) @llvm.experimental.gc.statepoint.p0f_isVoidf(i64 2882400000, i32 0, void ()* @safepoint, i32 0, i32 0, i32 0, i32 0)
+   br label %continue
+continue:
+; CHECK-LABEL: continue:
+; CHECK: phi
+; CHECK-DAG: [ %p.relocated, %safepoint ]
+; CHECK-DAG [ %p, %entry ]
+; CHECK: %cond = icmp
+; CHECK: br i1 %cond
+   br i1 %cond, label %taken, label %untaken
+taken:
+   ret i1 true
+untaken:
+   ret i1 false
+}
+
+; Comparing two pointers
+define i1 @test2(i8 addrspace(1)* %p, i8 addrspace(1)* %q, i1 %rare) 
+    gc "statepoint-example" {
+; CHECK-LABEL: @test2
+entry:   
+   %cond = icmp eq i8 addrspace(1)* %p, %q
+   br i1 %rare, label %safepoint, label %continue, !prof !0
+safepoint:
+   call i32 (i64, i32, void ()*, i32, i32, ...) @llvm.experimental.gc.statepoint.p0f_isVoidf(i64 2882400000, i32 0, void ()* @safepoint, i32 0, i32 0, i32 0, i32 0)
+   br label %continue
+continue:
+; CHECK-LABEL: continue:
+; CHECK: phi
+; CHECK-DAG: [ %q.relocated, %safepoint ]
+; CHECK-DAG [ %q, %entry ]
+; CHECK: phi
+; CHECK-DAG: [ %p.relocated, %safepoint ]
+; CHECK-DAG [ %p, %entry ]
+; CHECK: %cond = icmp
+; CHECK: br i1 %cond
+   br i1 %cond, label %taken, label %untaken
+taken:
+   ret i1 true
+untaken:
+   ret i1 false
+}
+
+; Sanity check that nothing bad happens if already last instruction
+; before terminator
+define i1 @test3(i8 addrspace(1)* %p, i8 addrspace(1)* %q, i1 %rare) 
+    gc "statepoint-example" {
+; CHECK-LABEL: @test3
+entry:   
+   call i32 (i64, i32, void ()*, i32, i32, ...) @llvm.experimental.gc.statepoint.p0f_isVoidf(i64 2882400000, i32 0, void ()* @safepoint, i32 0, i32 0, i32 0, i32 0)
+; CHECK: gc.statepoint
+; CHECK: %cond = icmp
+; CHECK: br i1 %cond
+   %cond = icmp eq i8 addrspace(1)* %p, %q
+   br i1 %cond, label %taken, label %untaken
+taken:
+   ret i1 true
+untaken:
+   ret i1 false
+}
+
+declare void @safepoint()
+declare i32 @llvm.experimental.gc.statepoint.p0f_isVoidf(i64, i32, void ()*, i32, i32, ...)
+
+!0 = !{!"branch_weights", i32 1, i32 10000}