[MemoryBuiltins] Add getFreedOperand() function (NFCI)

We currently assume in a number of places that free-like functions
free their first argument. This is true for all hardcoded free-like
functions, but with the new attribute-based design, the freed
argument is supposed to be indicated by the allocptr attribute.

To make sure we handle this correctly once allockind(free) is
respected, add a getFreedOperand() helper which returns the freed
argument, rather than just indicating whether the call frees *some*
argument.

This migrates most but not all users of isFreeCall() to the new
API. The remaining users are a bit more tricky.

1 files changed, 1 insertions, 1 deletions

diff --git a/llvm/lib/Analysis/GlobalsModRef.cpp b/llvm/lib/Analysis/GlobalsModRef.cpp
index 563a84e..e6ef1c7 100644
--- a/llvm/lib/Analysis/GlobalsModRef.cpp
+++ b/llvm/lib/Analysis/GlobalsModRef.cpp
@@ -361,7 +361,7 @@ bool GlobalsAAResult::AnalyzeUsesOfPointer(Value *V,
       if (Call->isDataOperand(&U)) {
         // Detect calls to free.
         if (Call->isArgOperand(&U) &&
-            isFreeCall(I, &GetTLI(*Call->getFunction()))) {
+            getFreedOperand(Call, &GetTLI(*Call->getFunction())) == U) {
           if (Writers)
             Writers->insert(Call->getParent()->getParent());
         } else {