DataLayout is mandatory, update the API to reflect it with references.

Summary:
Now that the DataLayout is a mandatory part of the module, let's start
cleaning the codebase. This patch is a first attempt at doing that.

This patch is not exactly NFC as for instance some places were passing
a nullptr instead of the DataLayout, possibly just because there was a
default value on the DataLayout argument to many functions in the API.
Even though it is not purely NFC, there is no change in the
validation.

I turned as many pointer to DataLayout to references, this helped
figuring out all the places where a nullptr could come up.

I had initially a local version of this patch broken into over 30
independant, commits but some later commit were cleaning the API and
touching part of the code modified in the previous commits, so it
seemed cleaner without the intermediate state.

Test Plan:

Reviewers: echristo

Subscribers: llvm-commits

From: Mehdi Amini <mehdi.amini@apple.com>
llvm-svn: 231740

1 files changed, 6 insertions, 18 deletions

diff --git a/llvm/lib/Transforms/IPO/ConstantMerge.cpp b/llvm/lib/Transforms/IPO/ConstantMerge.cpp
index 98077af..8ce7646 100644
--- a/llvm/lib/Transforms/IPO/ConstantMerge.cpp
+++ b/llvm/lib/Transforms/IPO/ConstantMerge.cpp
@@ -52,7 +52,6 @@ namespace {
     // alignment to a concrete value.
     unsigned getAlignment(GlobalVariable *GV) const;
 
-    const DataLayout *DL;
   };
 }
 
@@ -89,31 +88,22 @@ static bool IsBetterCanonical(const GlobalVariable &A,
   return A.hasUnnamedAddr();
 }
 
-bool ConstantMerge::hasKnownAlignment(GlobalVariable *GV) const {
-  return DL || GV->getAlignment() != 0;
-}
-
 unsigned ConstantMerge::getAlignment(GlobalVariable *GV) const {
   unsigned Align = GV->getAlignment();
   if (Align)
     return Align;
-  if (DL)
-    return DL->getPreferredAlignment(GV);
-  return 0;
+  return GV->getParent()->getDataLayout().getPreferredAlignment(GV);
 }
 
 bool ConstantMerge::runOnModule(Module &M) {
-  DL = &M.getDataLayout();
 
   // Find all the globals that are marked "used".  These cannot be merged.
   SmallPtrSet<const GlobalValue*, 8> UsedGlobals;
   FindUsedValues(M.getGlobalVariable("llvm.used"), UsedGlobals);
   FindUsedValues(M.getGlobalVariable("llvm.compiler.used"), UsedGlobals);
-  
-  // Map unique <constants, has-unknown-alignment> pairs to globals.  We don't
-  // want to merge globals of unknown alignment with those of explicit
-  // alignment.  If we have DataLayout, we always know the alignment.
-  DenseMap<PointerIntPair<Constant*, 1, bool>, GlobalVariable*> CMap;
+
+  // Map unique constants to globals.
+  DenseMap<Constant *, GlobalVariable *> CMap;
 
   // Replacements - This vector contains a list of replacements to perform.
   SmallVector<std::pair<GlobalVariable*, GlobalVariable*>, 32> Replacements;
@@ -155,8 +145,7 @@ bool ConstantMerge::runOnModule(Module &M) {
       Constant *Init = GV->getInitializer();
 
       // Check to see if the initializer is already known.
-      PointerIntPair<Constant*, 1, bool> Pair(Init, hasKnownAlignment(GV));
-      GlobalVariable *&Slot = CMap[Pair];
+      GlobalVariable *&Slot = CMap[Init];
 
       // If this is the first constant we find or if the old one is local,
       // replace with the current one. If the current is externally visible
@@ -187,8 +176,7 @@ bool ConstantMerge::runOnModule(Module &M) {
       Constant *Init = GV->getInitializer();
 
       // Check to see if the initializer is already known.
-      PointerIntPair<Constant*, 1, bool> Pair(Init, hasKnownAlignment(GV));
-      GlobalVariable *Slot = CMap[Pair];
+      GlobalVariable *Slot = CMap[Init];
 
       if (!Slot || Slot == GV)
         continue;