Reimplement isPotentiallyReachable to make nocapture deduction much stronger.
Adds unit tests for it too.
Split BasicBlockUtils into an analysis-half and a transforms-half, and put the
analysis bits into a new Analysis/CFG.{h,cpp}. Promote isPotentiallyReachable
into llvm::isPotentiallyReachable and move it into Analysis/CFG.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@187283 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Analysis/AliasAnalysis.cpp b/lib/Analysis/AliasAnalysis.cpp
index 5be5613..b8b6d37 100644
--- a/lib/Analysis/AliasAnalysis.cpp
+++ b/lib/Analysis/AliasAnalysis.cpp
@@ -26,6 +26,7 @@
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/Analysis/CaptureTracking.h"
+#include "llvm/Analysis/CFG.h"
#include "llvm/Analysis/Dominators.h"
#include "llvm/Analysis/ValueTracking.h"
#include "llvm/IR/BasicBlock.h"
@@ -361,26 +362,6 @@
}
namespace {
- /// Determine whether there is a path from From to To within a single
- /// function. Returns false only if we can prove that once 'From' has been
- /// executed then 'To' can not be executed. Conservatively returns true.
- static bool isPotentiallyReachable(const BasicBlock *From,
- const BasicBlock *To) {
- const unsigned MaxCheck = 5;
- const BasicBlock *Current = From;
- for (unsigned I = 0; I < MaxCheck; I++) {
- unsigned NumSuccs = Current->getTerminator()->getNumSuccessors();
- if (NumSuccs > 1)
- return true;
- if (NumSuccs == 0)
- return false;
- Current = Current->getTerminator()->getSuccessor(0);
- if (Current == To)
- return true;
- }
- return true;
- }
-
/// Only find pointer captures which happen before the given instruction. Uses
/// the dominator tree to determine whether one instruction is before another.
/// Only support the case where the Value is defined in the same basic block
@@ -402,7 +383,7 @@
// there is no need to explore the use if BeforeHere dominates use.
// Check whether there is a path from I to BeforeHere.
if (BeforeHere != I && DT->dominates(BeforeHere, I) &&
- !isPotentiallyReachable(BB, BeforeHere->getParent()))
+ !isPotentiallyReachable(I, BeforeHere, DT))
return false;
return true;
}
@@ -414,7 +395,7 @@
if (BeforeHere != I && !DT->isReachableFromEntry(BB))
return false;
if (BeforeHere != I && DT->dominates(BeforeHere, I) &&
- !isPotentiallyReachable(BB, BeforeHere->getParent()))
+ !isPotentiallyReachable(I, BeforeHere, DT))
return false;
Captured = true;
return true;