[llvm] r305146 - [EarlyCSE] Add option to use MemorySSA for function simplification run of EarlyCSE (off by default).

[Geoff Berry via llvm-commits]

Author: gberry
Date: Sat Jun 10 10:20:03 2017
New Revision: 305146

URL: http://llvm.org/viewvc/llvm-project?rev=305146&view=rev
Log:
[EarlyCSE] Add option to use MemorySSA for function simplification run of EarlyCSE (off by default).

Summary:
Use MemorySSA for memory dependency checking in the EarlyCSE pass at the
start of the function simplification portion of the pipeline.  We rely
on the fact that GVNHoist runs just after this pass of EarlyCSE to
amortize the MemorySSA construction cost since GVNHoist uses MemorySSA
and EarlyCSE preserves it.

This is turned off by default.  A follow-up change will turn it on to
allow for easier reversion in case it breaks something.

Modified:
    llvm/trunk/lib/Passes/PassBuilder.cpp
    llvm/trunk/lib/Transforms/IPO/PassManagerBuilder.cpp

Modified: llvm/trunk/lib/Passes/PassBuilder.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Passes/PassBuilder.cpp?rev=305146&r1=305145&r2=305146&view=diff
==============================================================================
--- llvm/trunk/lib/Passes/PassBuilder.cpp (original)
+++ llvm/trunk/lib/Passes/PassBuilder.cpp Sat Jun 10 10:20:03 2017
@@ -160,6 +160,10 @@ static cl::opt<bool>
               cl::Hidden, cl::ZeroOrMore,
               cl::desc("Run NewGVN instead of GVN"));
 
+static cl::opt<bool> EnableEarlyCSEMemSSA(
+    "enable-npm-earlycse-memssa", cl::init(false), cl::Hidden,
+    cl::desc("Enable the EarlyCSE w/ MemorySSA pass for the new PM (default = off)"));
+
 static cl::opt<bool> EnableGVNHoist(
     "enable-npm-gvn-hoist", cl::init(false), cl::Hidden,
     cl::desc("Enable the GVN hoisting pass for the new PM (default = off)"));
@@ -312,7 +316,7 @@ PassBuilder::buildFunctionSimplification
   FPM.addPass(SROA());
 
   // Catch trivial redundancies
-  FPM.addPass(EarlyCSEPass());
+  FPM.addPass(EarlyCSEPass(EnableEarlyCSEMemSSA));
 
   // Hoisting of scalars and load expressions.
   if (EnableGVNHoist)

Modified: llvm/trunk/lib/Transforms/IPO/PassManagerBuilder.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/IPO/PassManagerBuilder.cpp?rev=305146&r1=305145&r2=305146&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/IPO/PassManagerBuilder.cpp (original)
+++ llvm/trunk/lib/Transforms/IPO/PassManagerBuilder.cpp Sat Jun 10 10:20:03 2017
@@ -141,6 +141,10 @@ static cl::opt<int> PreInlineThreshold(
     cl::desc("Control the amount of inlining in pre-instrumentation inliner "
              "(default = 75)"));
 
+static cl::opt<bool> EnableEarlyCSEMemSSA(
+    "enable-earlycse-memssa", cl::init(false), cl::Hidden,
+    cl::desc("Enable the EarlyCSE w/ MemorySSA pass (default = off)"));
+
 static cl::opt<bool> EnableGVNHoist(
     "enable-gvn-hoist", cl::init(false), cl::Hidden,
     cl::desc("Enable the GVN hoisting pass (default = off)"));
@@ -308,7 +312,7 @@ void PassManagerBuilder::addFunctionSimp
   // Start of function pass.
   // Break up aggregate allocas, using SSAUpdater.
   MPM.add(createSROAPass());
-  MPM.add(createEarlyCSEPass());              // Catch trivial redundancies
+  MPM.add(createEarlyCSEPass(EnableEarlyCSEMemSSA)); // Catch trivial redundancies
   if (EnableGVNHoist)
     MPM.add(createGVNHoistPass());
   if (EnableGVNSink) {