[PATCH] D96081: Option to ignore assume like intrinsic uses in hasAddressTaken()

[Stanislav Mekhanoshin via Phabricator via llvm-commits]

rampitec updated this revision to Diff 321614.
rampitec added a comment.

Fixed bug if cast is unused.


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D96081/new/

https://reviews.llvm.org/D96081

Files:
  llvm/include/llvm/IR/Function.h
  llvm/lib/Analysis/CallGraph.cpp
  llvm/lib/IR/Function.cpp
  llvm/test/Analysis/CallGraph/ignore-assumelike-calls.ll


Index: llvm/test/Analysis/CallGraph/ignore-assumelike-calls.ll
===================================================================
--- /dev/null
+++ llvm/test/Analysis/CallGraph/ignore-assumelike-calls.ll
@@ -0,0 +1,26 @@
+; RUN: opt < %s -print-callgraph -disable-output 2>&1 | FileCheck %s
+; CHECK: Call graph node <<null function>><<{{.*}}>>  #uses=0
+; CHECK-NEXT:   CS<None> calls function 'cast_only'
+; CHECK-NEXT:   CS<None> calls function 'llvm.lifetime.start.p0i8'
+; CHECK-EMPTY:
+; CHECK-NEXT:   Call graph node for function: 'cast_only'<<{{.*}}>>  #uses=1
+; CHECK-EMPTY:
+; CHECK-NEXT:   Call graph node for function: 'llvm.lifetime.start.p0i8'<<{{.*}}>>  #uses=1
+; CHECK-EMPTY:
+; CHECK-NEXT:   Call graph node for function: 'used_by_lifetime'<<{{.*}}>>  #uses=0
+; CHECK-EMPTY:
+
+define internal void @used_by_lifetime() {
+entry:
+  %c = bitcast void()* @used_by_lifetime to i8*
+  call void @llvm.lifetime.start.p0i8(i64 4, i8* %c)
+  ret void
+}
+
+define internal void @cast_only() {
+entry:
+  %c = bitcast void()* @cast_only to i8*
+  ret void
+}
+
+declare void @llvm.lifetime.start.p0i8(i64, i8* nocapture)
Index: llvm/lib/IR/Function.cpp
===================================================================
--- llvm/lib/IR/Function.cpp
+++ llvm/lib/IR/Function.cpp
@@ -31,6 +31,7 @@
 #include "llvm/IR/InstIterator.h"
 #include "llvm/IR/Instruction.h"
 #include "llvm/IR/Instructions.h"
+#include "llvm/IR/IntrinsicInst.h"
 #include "llvm/IR/Intrinsics.h"
 #include "llvm/IR/IntrinsicsAArch64.h"
 #include "llvm/IR/IntrinsicsAMDGPU.h"
@@ -1580,7 +1581,8 @@
 /// other than direct calls or invokes to it. Optionally ignores callback
 /// uses.
 bool Function::hasAddressTaken(const User **PutOffender,
-                               bool IgnoreCallbackUses) const {
+                               bool IgnoreCallbackUses,
+                               bool IgnoreAssumeLikeCalls) const {
   for (const Use &U : uses()) {
     const User *FU = U.getUser();
     if (isa<BlockAddress>(FU))
@@ -1594,6 +1596,17 @@
 
     const auto *Call = dyn_cast<CallBase>(FU);
     if (!Call) {
+      if (IgnoreAssumeLikeCalls) {
+        if (const auto *FI = dyn_cast<Instruction>(FU)) {
+          if (FI->isCast() && !FI->user_empty() &&
+              llvm::all_of(FU->users(), [](const User *U) {
+                if (const auto *I = dyn_cast<IntrinsicInst>(U))
+                  return I->isAssumeLikeIntrinsic();
+                return false;
+              }))
+            continue;
+        }
+      }
       if (PutOffender)
         *PutOffender = FU;
       return true;
Index: llvm/lib/Analysis/CallGraph.cpp
===================================================================
--- llvm/lib/Analysis/CallGraph.cpp
+++ llvm/lib/Analysis/CallGraph.cpp
@@ -80,7 +80,8 @@
   // If this function has external linkage or has its address taken and
   // it is not a callback, then anything could call it.
   if (!F->hasLocalLinkage() ||
-      F->hasAddressTaken(nullptr, /*IgnoreCallbackUses=*/true))
+      F->hasAddressTaken(nullptr, /*IgnoreCallbackUses=*/true,
+                         /* IgnoreAssumeLikeCalls */ true))
     ExternalCallingNode->addCalledFunction(nullptr, Node);
 
   populateCallGraphNode(Node);
Index: llvm/include/llvm/IR/Function.h
===================================================================
--- llvm/include/llvm/IR/Function.h
+++ llvm/include/llvm/IR/Function.h
@@ -876,7 +876,8 @@
   /// ignores callback uses.
   ///
   bool hasAddressTaken(const User ** = nullptr,
-                       bool IgnoreCallbackUses = false) const;
+                       bool IgnoreCallbackUses = false,
+                       bool IgnoreAssumeLikeCalls = false) const;
 
   /// isDefTriviallyDead - Return true if it is trivially safe to remove
   /// this function definition from the module (because it isn't externally


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