From 4ea02c59d8c9223cae9eab7ae0ab1d3e42702554 Mon Sep 17 00:00:00 2001
From: "james.brodman" <james.brodman@intel.com>
Date: Tue, 21 May 2013 10:00:22 -0400
Subject: [PATCH 1/2] Disable break optimization and change return check to use
 full mask.

---
 ctx.cpp  | 2 +-
 stmt.cpp | 3 +++
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/ctx.cpp b/ctx.cpp
index 872751eb..5b93c8bc 100644
--- a/ctx.cpp
+++ b/ctx.cpp
@@ -1266,7 +1266,7 @@ FunctionEmitContext::CurrentLanesReturned(Expr *expr, bool doCoherenceCheck) {
             LoadInst(returnedLanesPtr, "old_returned_lanes");
         llvm::Value *newReturnedLanes =
             BinaryOperator(llvm::Instruction::Or, oldReturnedLanes,
-                           GetInternalMask(), "old_mask|returned_lanes");
+                           GetFullMask(), "old_mask|returned_lanes");
 
         // For 'coherent' return statements, emit code to check if all
         // lanes have returned
diff --git a/stmt.cpp b/stmt.cpp
index a95f8fbf..eba506ab 100644
--- a/stmt.cpp
+++ b/stmt.cpp
@@ -447,6 +447,8 @@ IfStmt::EmitCode(FunctionEmitContext *ctx) const {
         ctx->SetCurrentBasicBlock(bexit);
         ctx->EndIf();
     }
+    /*
+    // Disabled for performance reasons.  Change to an optional compile-time opt switch.
     else if (lCanApplyBreakOptimization(trueStmts, falseStmts)) {
         // If we have a simple break statement inside the 'if' and are
         // under varying control flow, just update the execution mask
@@ -456,6 +458,7 @@ IfStmt::EmitCode(FunctionEmitContext *ctx) const {
         // benefit in this case.
         ctx->SetInternalMaskAndNot(ctx->GetInternalMask(), testValue);
     }
+    */
     else
         emitVaryingIf(ctx, testValue);
 }

From 403d9e105913512969cc86ed061bb6657f6670f8 Mon Sep 17 00:00:00 2001
From: "james.brodman" <james.brodman@intel.com>
Date: Tue, 21 May 2013 10:52:38 -0400
Subject: [PATCH 2/2] Update break/continue test to use contribution of
 function mask.

---
 ctx.cpp  | 7 +++++++
 stmt.cpp | 3 ++-
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/ctx.cpp b/ctx.cpp
index 5b93c8bc..b7691f15 100644
--- a/ctx.cpp
+++ b/ctx.cpp
@@ -841,6 +841,9 @@ FunctionEmitContext::jumpIfAllLoopLanesAreDone(llvm::BasicBlock *target) {
     if (breakLanesPtr == NULL) {
         llvm::Value *continued = LoadInst(continueLanesPtr,
                                           "continue_lanes");
+        continued = BinaryOperator(llvm::Instruction::And,
+                                   continued, GetFunctionMask(),
+                                   "continued&func");
         allDone = MasksAllEqual(continued, blockEntryMask);
     }
     else {
@@ -860,6 +863,10 @@ FunctionEmitContext::jumpIfAllLoopLanesAreDone(llvm::BasicBlock *target) {
             finishedLanes = BinaryOperator(llvm::Instruction::Or, finishedLanes,
                                            continued, "returned|breaked|continued");
         }
+        
+        finishedLanes = BinaryOperator(llvm::Instruction::And,
+                                       finishedLanes, GetFunctionMask(),
+                                       "finished&func");
 
         // Do we match the mask at loop or switch statement entry?
         allDone = MasksAllEqual(finishedLanes, blockEntryMask);
diff --git a/stmt.cpp b/stmt.cpp
index eba506ab..4ec63d35 100644
--- a/stmt.cpp
+++ b/stmt.cpp
@@ -374,6 +374,7 @@ lEmitIfStatements(FunctionEmitContext *ctx, Stmt *stmts, const char *trueOrFalse
 
 /** Returns true if the "true" block for the if statement consists of a
     single 'break' statement, and the "false" block is empty. */
+/*
 static bool
 lCanApplyBreakOptimization(Stmt *trueStmts, Stmt *falseStmts) {
     if (falseStmts != NULL) {
@@ -392,7 +393,7 @@ lCanApplyBreakOptimization(Stmt *trueStmts, Stmt *falseStmts) {
     else
         return false;
 }
-
+*/
 
 void
 IfStmt::EmitCode(FunctionEmitContext *ctx) const {