[PATCH] D17430: [ifcnv] Add comment explaining why it's OK to duplicate convergent MIs in ifcnv.
Justin Lebar via llvm-commits
llvm-commits at lists.llvm.org
Mon Feb 22 09:56:04 PST 2016
This revision was automatically updated to reflect the committed changes.
Closed by commit rL261543: [ifcnv] Add comment explaining why it's OK to duplicate convergent MIs in ifcnv. (authored by jlebar).
Changed prior to commit:
http://reviews.llvm.org/D17430?vs=48554&id=48705#toc
Repository:
rL LLVM
http://reviews.llvm.org/D17430
Files:
llvm/trunk/lib/CodeGen/IfConversion.cpp
Index: llvm/trunk/lib/CodeGen/IfConversion.cpp
===================================================================
--- llvm/trunk/lib/CodeGen/IfConversion.cpp
+++ llvm/trunk/lib/CodeGen/IfConversion.cpp
@@ -7,7 +7,8 @@
//
//===----------------------------------------------------------------------===//
//
-// This file implements the machine instruction level if-conversion pass.
+// This file implements the machine instruction level if-conversion pass, which
+// tries to convert conditional branches into predicated instructions.
//
//===----------------------------------------------------------------------===//
@@ -673,6 +674,9 @@
if (I->isDebugValue())
continue;
+ // Don't need to check isConvergent(). It's OK to duplicate convergent
+ // instructions here, because we'll only push convergent operations up the
+ // CFG -- this can only *remove* control-flow dependencies.
if (I->isNotDuplicable())
BBI.CannotBeCopied = true;
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