[PATCH] D77601: Make SmallVector assert if it cannot grow.

[Andrew via Phabricator via llvm-commits]

browneee updated this revision to Diff 259123.
browneee added a comment.

Rebase to head.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D77601/new/

https://reviews.llvm.org/D77601

Files:
  llvm/include/llvm/ADT/SmallVector.h
  llvm/lib/Support/SmallVector.cpp


Index: llvm/lib/Support/SmallVector.cpp
===================================================================
--- llvm/lib/Support/SmallVector.cpp
+++ llvm/lib/Support/SmallVector.cpp
@@ -39,12 +39,19 @@
 
 /// grow_pod - This is an implementation of the grow() method which only works
 /// on POD-like datatypes and is out of line to reduce code duplication.
+/// This function will report a fatal error if it cannot increase capacity.
 void SmallVectorBase::grow_pod(void *FirstEl, size_t MinCapacity,
                                size_t TSize) {
   // Ensure we can fit the new capacity in 32 bits.
   if (MinCapacity > UINT32_MAX)
     report_bad_alloc_error("SmallVector capacity overflow during allocation");
 
+  // Ensure we can meet the guarantee of space for at least one more element.
+  // The above check alone will not catch the case where grow is called with a
+  // default MinCapacity of 0, but the current capacity cannot be increased.
+  if (capacity() == size_t(UINT32_MAX))
+    report_bad_alloc_error("SmallVector capacity unable to grow");
+
   size_t NewCapacity = 2 * capacity() + 1; // Always grow.
   NewCapacity =
       std::min(std::max(NewCapacity, MinCapacity), size_t(UINT32_MAX));
Index: llvm/include/llvm/ADT/SmallVector.h
===================================================================
--- llvm/include/llvm/ADT/SmallVector.h
+++ llvm/include/llvm/ADT/SmallVector.h
@@ -46,6 +46,7 @@
 
   /// This is an implementation of the grow() method which only works
   /// on POD-like data types and is out of line to reduce code duplication.
+  /// This function will report a fatal error if it cannot increase capacity.
   void grow_pod(void *FirstEl, size_t MinCapacity, size_t TSize);
 
 public:
@@ -234,6 +235,12 @@
   if (MinSize > UINT32_MAX)
     report_bad_alloc_error("SmallVector capacity overflow during allocation");
 
+  // Ensure we can meet the guarantee of space for at least one more element.
+  // The above check alone will not catch the case where grow is called with a
+  // default MinCapacity of 0, but the current capacity cannot be increased.
+  if (this->capacity() == size_t(UINT32_MAX))
+    report_bad_alloc_error("SmallVector capacity unable to grow");
+
   // Always grow, even from zero.
   size_t NewCapacity = size_t(NextPowerOf2(this->capacity() + 2));
   NewCapacity = std::min(std::max(NewCapacity, MinSize), size_t(UINT32_MAX));


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