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Add C++ global operator {new,new[],delete,delete[]}(unsigned {int,long}) to the 

memory builtins as equivalent to malloc/free.

This is different from any attribute we have. For example, you can delete the
allocators when their result is unused, but you can't collapse two calls to the
same function, even if no global/memory state has changed in between. The
noalias return states that the result does not alias any other pointer, but
instcombine optimizes malloc() as though the result is non-null for the purpose
of eliminating unused pointers.

llvm-svn: 127673
This commit is contained in:
Nick Lewycky 2011-03-15 07:31:32 +00:00
parent e3ae0a4c47
commit c1f8658368
1 changed files with 11 additions and 2 deletions
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13
llvm/lib/Analysis/MemoryBuiltins.cpp
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@ -35,7 +35,11 @@ static bool isMallocCall(const CallInst *CI) {
return false;
Function *Callee = CI->getCalledFunction();
if (Callee == 0 || !Callee->isDeclaration() || Callee->getName() != "malloc")
if (Callee == 0 || !Callee->isDeclaration())
return false;
if (Callee->getName() != "malloc" &&
Callee->getName() != "_Znwj" && Callee->getName() != "_Znwm" &&
Callee->getName() != "_Znaj" && Callee->getName() != "_Znam")
return false;
// Check malloc prototype.
@ -189,7 +193,12 @@ const CallInst *llvm::isFreeCall(const Value *I) {
if (!CI)
return 0;
Function *Callee = CI->getCalledFunction();
if (Callee == 0 || !Callee->isDeclaration() || Callee->getName() != "free")
if (Callee == 0 || !Callee->isDeclaration())
return 0;
if (Callee->getName() != "free" &&
Callee->getName() != "_Zdlj" && Callee->getName() != "_Zdlm" &&
Callee->getName() != "_Zdaj" && Callee->getName() != "_Zdam")
return 0;
// Check free prototype.