Update comments and documentation to reflect that GCSE and ValueNumbering are

deprecated by the GVN and GVNPRE passes.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@51983 91177308-0d34-0410-b5e6-96231b3b80d8

5 files changed, 34 insertions, 3 deletions

diff --git a/docs/Passes.html b/docs/Passes.html
index 21b03f5..bb1a64b 100644
--- a/docs/Passes.html
+++ b/docs/Passes.html
@@ -298,7 +298,7 @@ perl -e '$/ = undef; for (split(/\n/, <>)) { s:^ *///? ?::; print "  <p>\n" if !
 
 <!-------------------------------------------------------------------------- -->
 <div class="doc_subsection">
-  <a name="basicvn">Basic Value Numbering (default GVN impl)</a>
+  <a name="basicvn">Basic Value Numbering (default Value Numbering impl)</a>
 </div>
 <div class="doc_text">
   <p>
@@ -307,6 +307,12 @@ perl -e '$/ = undef; for (split(/\n/, <>)) { s:^ *///? ?::; print "  <p>\n" if !
   lexically identical expressions.  This does not require any ahead of time
   analysis, so it is a very fast default implementation.
   </p>
+  <p>
+  The ValueNumbering analysis passes are mostly deprecated. They are only used
+  by the <a href="#gcse">Global Common Subexpression Elimination pass</a>, which
+  is deprecated by the <a href="#gvn">Global Value Numbering pass</a> (which
+  does its value numbering on its own).
+  </p>
 </div>
 
 <!-------------------------------------------------------------------------- -->
@@ -859,9 +865,13 @@ perl -e '$/ = undef; for (split(/\n/, <>)) { s:^ *///? ?::; print "  <p>\n" if !
   <p>
   This pass is designed to be a very quick global transformation that
   eliminates global common subexpressions from a function.  It does this by
-  using an existing value numbering implementation to identify the common
+  using an existing value numbering analysis pass to identify the common
   subexpressions, eliminating them when possible.
   </p>
+  <p>
+  This pass is deprecated by the <a href="#gvn">Global Value Numbering pass</a>
+  (which does a better job with its own value numbering).
+  </p>
 </div>
 
 <!-------------------------------------------------------------------------- -->
@@ -899,6 +909,10 @@ perl -e '$/ = undef; for (split(/\n/, <>)) { s:^ *///? ?::; print "  <p>\n" if !
   This pass performs global value numbering to eliminate fully redundant
   instructions.  It also performs simple dead load elimination.
   </p>
+  <p>
+  Note that this pass does the value numbering itself, it does not use the
+  ValueNumbering analysis passes.
+  </p>
 </div>
 
 <!-------------------------------------------------------------------------- -->
@@ -916,6 +930,10 @@ perl -e '$/ = undef; for (split(/\n/, <>)) { s:^ *///? ?::; print "  <p>\n" if !
   live ranges, and should be used with caution on platforms that are very 
   sensitive to register pressure.
   </p>
+  <p>
+  Note that this pass does the value numbering itself, it does not use the
+  ValueNumbering analysis passes.
+  </p>
 </div>
 
 <!-------------------------------------------------------------------------- -->
diff --git a/lib/Analysis/ValueNumbering.cpp b/lib/Analysis/ValueNumbering.cpp
index 98f04bd..55323ea 100644
--- a/lib/Analysis/ValueNumbering.cpp
+++ b/lib/Analysis/ValueNumbering.cpp
@@ -10,6 +10,10 @@
 // This file implements the non-abstract Value Numbering methods as well as a
 // default implementation for the analysis group.
 //
+// The ValueNumbering analysis pass is mostly deprecated. It is only used by the
+// Global Common Subexpression Elimination pass, which is deprecated by the
+// Global Value Numbering pass (which does its value numbering on its own).
+//
 //===----------------------------------------------------------------------===//
 
 #include "llvm/Analysis/Passes.h"
diff --git a/lib/Transforms/Scalar/GCSE.cpp b/lib/Transforms/Scalar/GCSE.cpp
index 35752bb..94cdcb1 100644
--- a/lib/Transforms/Scalar/GCSE.cpp
+++ b/lib/Transforms/Scalar/GCSE.cpp
@@ -9,9 +9,12 @@
 //
 // This pass is designed to be a very quick global transformation that
 // eliminates global common subexpressions from a function.  It does this by
-// using an existing value numbering implementation to identify the common
+// using an existing value numbering analysis pass to identify the common
 // subexpressions, eliminating them when possible.
 //
+// This pass is deprecated by the Global Value Numbering pass (which does a
+// better job with its own value numbering).
+//
 //===----------------------------------------------------------------------===//
 
 #define DEBUG_TYPE "gcse"
diff --git a/lib/Transforms/Scalar/GVN.cpp b/lib/Transforms/Scalar/GVN.cpp
index fcfe3c5..e223281 100644
--- a/lib/Transforms/Scalar/GVN.cpp
+++ b/lib/Transforms/Scalar/GVN.cpp
@@ -10,6 +10,9 @@
 // This pass performs global value numbering to eliminate fully redundant
 // instructions.  It also performs simple dead load elimination.
 //
+// Note that this pass does the value numbering itself, it does not use the
+// ValueNumbering analysis passes.
+//
 //===----------------------------------------------------------------------===//
 
 #define DEBUG_TYPE "gvn"
diff --git a/lib/Transforms/Scalar/GVNPRE.cpp b/lib/Transforms/Scalar/GVNPRE.cpp
index 1746fd8..e0c869f 100644
--- a/lib/Transforms/Scalar/GVNPRE.cpp
+++ b/lib/Transforms/Scalar/GVNPRE.cpp
@@ -16,6 +16,9 @@
 // live ranges, and should be used with caution on platforms that are very 
 // sensitive to register pressure.
 //
+// Note that this pass does the value numbering itself, it does not use the
+// ValueNumbering analysis passes.
+//
 //===----------------------------------------------------------------------===//
 
 #define DEBUG_TYPE "gvnpre"