Commit 68cf62a5 authored by Bill Wendling's avatar Bill Wendling
Browse files

Approved by Chris: 

$ svn merge -c 113911 https://llvm.org/svn/llvm-project/llvm/trunk
--- Merging r113911 into '.':
U    test/Transforms/ConstantMerge/dont-merge.ll
U    lib/Transforms/IPO/ConstantMerge.cpp

llvm-svn: 113912
parent 1c8b0a18

llvm/lib/Transforms/IPO/ConstantMerge.cpp

+27 −1
Original line number Diff line number Diff line
@@ -19,10 +19,12 @@ 


#define DEBUG_TYPE "constmerge"

#include "llvm/Transforms/IPO.h"

#include "llvm/Constants.h"

#include "llvm/DerivedTypes.h"

#include "llvm/Module.h"

#include "llvm/Pass.h"

#include "llvm/ADT/DenseMap.h"

#include "llvm/ADT/SmallPtrSet.h"

#include "llvm/ADT/Statistic.h"

using namespace llvm;
@@ -46,7 +48,27 @@ INITIALIZE_PASS(ConstantMerge, "constmerge", 


ModulePass *llvm::createConstantMergePass() { return new ConstantMerge(); }







/// Find values that are marked as llvm.used.

static void FindUsedValues(GlobalVariable *LLVMUsed,

                           SmallPtrSet<const GlobalValue*, 8> &UsedValues) {

  if (LLVMUsed == 0) return;

  ConstantArray *Inits = dyn_cast<ConstantArray>(LLVMUsed->getInitializer());

  if (Inits == 0) return;

  

  for (unsigned i = 0, e = Inits->getNumOperands(); i != e; ++i)

    if (GlobalValue *GV = 

        dyn_cast<GlobalValue>(Inits->getOperand(i)->stripPointerCasts()))

      UsedValues.insert(GV);

}



bool ConstantMerge::runOnModule(Module &M) {

  // 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 constant/section pairs to globals.  We don't want to merge

  // globals in different sections.

  DenseMap<Constant*, GlobalVariable*> CMap;
@@ -79,9 +101,13 @@ bool ConstantMerge::runOnModule(Module &M) { 
      

      // Only process constants with initializers in the default addres space.

      if (!GV->isConstant() ||!GV->hasDefinitiveInitializer() ||

          GV->getType()->getAddressSpace() != 0 || !GV->getSection().empty())

          GV->getType()->getAddressSpace() != 0 || !GV->getSection().empty() ||

          // Don't touch values marked with attribute(used).

          UsedGlobals.count(GV))

        continue;

      

      

      

      Constant *Init = GV->getInitializer();



      // Check to see if the initializer is already known.

llvm/test/Transforms/ConstantMerge/dont-merge.ll

+14 −0
Original line number Diff line number Diff line
@@ -28,3 +28,17 @@ define void @test2(i32** %P1, i32 addrspace(30)** %P2) { 
        store i32 addrspace(30)*  @T2b, i32 addrspace(30)** %P2

        ret void

}



; PR8144 - Don't merge globals marked attribute(used)

; CHECK: @T3A = 

; CHECK: @T3B = 



@T3A = internal constant i32 0

@T3B = internal constant i32 0

@llvm.used = appending global [2 x i32*] [i32* @T3A, i32* @T3B], section

"llvm.metadata"



define void @test3() {

  call void asm sideeffect "T3A, T3B",""() ; invisible use of T3A and T3B

  ret void

}