commit c335d183cffdbe2f6041789bfcb7aad5148663c2
author Tatiana Shpeisman <shpeisman@google.com> Fri Aug 03 11:12:34 2018 -0700
committer jpienaar <jpienaar@google.com> Fri Mar 29 12:55:06 2019 -0700
tree c0349260fcf73fa1f0ae6b9cad497e521d829985
parent baf1bcafbfe7e29a06f04b129785e77c6c552840

Fix segfaults when printing unlinked statements, instructions and blocks. Fancy printing requires a pointer to the function since SSA values get function-specific names. This CL adds checks to ensure that we don't dereference null pointers in unliked objects. Unlinked statements, instructions and blocks are printed as <<UNLINKED STATEMENT>> etc.

PiperOrigin-RevId: 207293992

lib/IR/AsmPrinter.cpp

diff --git a/lib/IR/AsmPrinter.cpp b/lib/IR/AsmPrinter.cpp
index c53c333..d71fb92 100644
--- a/lib/IR/AsmPrinter.cpp
+++ b/lib/IR/AsmPrinter.cpp
@@ -582,6 +582,7 @@
   }
 
   void printOperand(const SSAValue *value) { printValueID(value); }
+
   void printOptionalAttrDict(ArrayRef<NamedAttribute> attrs,
                              ArrayRef<const char *> elidedAttrs = {}) override;
 
@@ -1182,6 +1183,10 @@
 void SSAValue::dump() const { print(llvm::errs()); }
 
 void Instruction::print(raw_ostream &os) const {
+  if (!getFunction()) {
+    os << "<<UNLINKED INSTRUCTION>>\n";
+    return;
+  }
   ModuleState state(getFunction()->getContext());
   ModulePrinter modulePrinter(os, state);
   CFGFunctionPrinter(getFunction(), modulePrinter).print(this);
@@ -1193,6 +1198,10 @@
 }
 
 void BasicBlock::print(raw_ostream &os) const {
+  if (!getFunction()) {
+    os << "<<UNLINKED BLOCK>>\n";
+    return;
+  }
   ModuleState state(getFunction()->getContext());
   ModulePrinter modulePrinter(os, state);
   CFGFunctionPrinter(getFunction(), modulePrinter).print(this);
@@ -1202,6 +1211,11 @@
 
 void Statement::print(raw_ostream &os) const {
   MLFunction *function = findFunction();
+  if (!function) {
+    os << "<<UNLINKED STATEMENT>>\n";
+    return;
+  }
+
   ModuleState state(function->getContext());
   ModulePrinter modulePrinter(os, state);
   MLFunctionPrinter(function, modulePrinter).print(this);