Current implementation of Value::replaceUsesExceptBlockAddr() uses UseList

iterator to walk the list which keeps changing inside the loop. When the
UseList contains several uses with the same user, we end processing the same
user more than once, which leads to an assert.

With this fix, unique users are saved and processed later to avoid
processing duplicates.

Differential Revision: https://reviews.llvm.org/D39864

llvm-svn: 318477

diff --git a/llvm/lib/IR/Value.cpp b/llvm/lib/IR/Value.cpp
index bfd3911..50235d8 100644 (file)
--- a/llvm/lib/IR/Value.cpp
+++ b/llvm/lib/IR/Value.cpp
@@ -15,6 +15,7 @@
 #include "LLVMContextImpl.h"
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/SmallString.h"
+#include "llvm/ADT/SetVector.h"
 #include "llvm/IR/CallSite.h"
 #include "llvm/IR/Constant.h"
 #include "llvm/IR/Constants.h"
@@ -456,6 +457,7 @@ void Value::replaceUsesOutsideBlock(Value *New, BasicBlock *BB) {
 }
 
 void Value::replaceUsesExceptBlockAddr(Value *New) {
+  SmallSetVector<Constant *, 4> Constants;
   use_iterator UI = use_begin(), E = use_end();
   for (; UI != E;) {
     Use &U = *UI;
@@ -468,13 +470,19 @@ void Value::replaceUsesExceptBlockAddr(Value *New) {
     // constant because they are uniqued.
     if (auto *C = dyn_cast<Constant>(U.getUser())) {
       if (!isa<GlobalValue>(C)) {
-        C->handleOperandChange(this, New);
+        // Save unique users to avoid processing operand replacement
+        // more than once.
+        Constants.insert(C);
         continue;
       }
     }
 
     U.set(New);
   }
+
+  // Process operand replacement of saved constants.
+  for (auto *C : Constants)
+    C->handleOperandChange(this, New);
 }
 
 namespace {

diff --git a/llvm/test/Transforms/LowerTypeTests/blockaddress-2.ll b/llvm/test/Transforms/LowerTypeTests/blockaddress-2.ll
new file mode 100644 (file)
index 0000000..b39a7bc
--- /dev/null
+++ b/llvm/test/Transforms/LowerTypeTests/blockaddress-2.ll
@@ -0,0 +1,26 @@
+; RUN: opt -S %s -lowertypetests | FileCheck %s
+
+; CHECK: @badfileops = internal global %struct.f { void ()* @bad_f, void ()* @bad_f }
+; CHECK: @bad_f = internal alias void (), void ()* @.cfi.jumptable
+; CHECK: define internal void @bad_f.cfi() !type !0 {
+; CHECK-NEXT:  ret void
+
+target triple = "x86_64-unknown-linux"
+
+%struct.f = type { void ()*, void ()* }
+@badfileops = internal global %struct.f { void ()* @bad_f, void ()* @bad_f }, align 8
+
+declare i1 @llvm.type.test(i8*, metadata)
+
+define internal void @bad_f() !type !1 {
+  ret void
+}
+
+define internal fastcc void @do_f() unnamed_addr !type !2 {
+  %1 = tail call i1 @llvm.type.test(i8* undef, metadata !"_ZTSFiP4fileP3uioP5ucrediP6threadE"), !nosanitize !3
+  ret void
+}
+
+!1 = !{i64 0, !"_ZTSFiP4fileP3uioP5ucrediP6threadE"}
+!2 = !{i64 0, !"_ZTSFiP6threadiP4fileP3uioliE"}
+!3 = !{}