From: Jakob Stoklund Olesen <stoklund@2pi.dk>
Date: Tue, 31 Aug 2010 01:27:49 +0000 (+0000)
Subject: Add experimental -disable-physical-join command line option.
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=e49e6a852b29b4f5fb13160ca3d2cc316f43030b;p=oota-llvm.git

Add experimental -disable-physical-join command line option.

Eventually, we want to disable physreg coalescing completely, and let the
register allocator do its job using hints.

This option makes it possible to measure the impact of disabling physreg
coalescing.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@112567 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/CodeGen/SimpleRegisterCoalescing.cpp b/lib/CodeGen/SimpleRegisterCoalescing.cpp
index 34c484103cf..5dd5fdb7b15 100644
--- a/lib/CodeGen/SimpleRegisterCoalescing.cpp
+++ b/lib/CodeGen/SimpleRegisterCoalescing.cpp
@@ -59,6 +59,11 @@ DisableCrossClassJoin("disable-cross-class-join",
                cl::desc("Avoid coalescing cross register class copies"),
                cl::init(false), cl::Hidden);
 
+static cl::opt<bool>
+DisablePhysicalJoin("disable-physical-join",
+               cl::desc("Avoid coalescing physical register copies"),
+               cl::init(false), cl::Hidden);
+
 INITIALIZE_AG_PASS(SimpleRegisterCoalescing, RegisterCoalescer,
                 "simple-register-coalescing", "Simple Register Coalescing", 
                 false, false, true);
@@ -1036,6 +1041,11 @@ bool SimpleRegisterCoalescing::JoinCopy(CopyRec &TheCopy, bool &Again) {
     return false;  // Not coalescable.
   }
 
+  if (DisablePhysicalJoin && CP.isPhys()) {
+    DEBUG(dbgs() << "\tPhysical joins disabled.\n");
+    return false;
+  }
+
   DEBUG(dbgs() << "\tConsidering merging %reg" << CP.getSrcReg());
 
   // Enforce policies.