Merged PR 96029: Reduce the scope of a fix to address a perf bug

Penguinwizzard · Penguinwizzard · commit 156a58e6f4b4 · 2017-12-01T00:06:01.000Z
The change to do this got undone by a fullsync issue when it was done in dev3 (https://microsoft.visualstudio.com/_git/os/commit/6933d4be4f827062c7b62b5f694001efc4891162), and in the meanwhile the macros were removed with the 1711 public release branch merge. In order to get everything into the right state, I'm targeting this at the same branch as the 1711 release.
diff --git a/lib/Parser/Scan.h b/lib/Parser/Scan.h
@@ -481,14 +481,9 @@ class Scanner : public IScanner, public EncodingPolicy
     charcount_t IchMinTok(void) const
     {
 
-        AssertOrFailFast(m_pchMinTok - m_pchBase >= 0);
-        AssertOrFailFast(m_pchMinTok - m_pchBase <= LONG_MAX);
-        if (static_cast<charcount_t>(m_pchMinTok - m_pchBase) < m_cMinTokMultiUnits)
-        {
-            AssertMsg(false, "IchMinTok subtraction overflow");
-            return 0;
-        }
-
+        Assert(m_pchMinTok - m_pchBase >= 0);
+        Assert(m_pchMinTok - m_pchBase <= LONG_MAX);
+        Assert(static_cast<charcount_t>(m_pchMinTok - m_pchBase) >= m_cMinTokMultiUnits);
         return static_cast<charcount_t>(m_pchMinTok - m_pchBase - m_cMinTokMultiUnits);
     }
 
@@ -497,15 +492,10 @@ class Scanner : public IScanner, public EncodingPolicy
     charcount_t IchLimTok(void) const
     {
 
-        AssertOrFailFast(m_currentCharacter - m_pchBase >= 0);
-        AssertOrFailFast(m_currentCharacter - m_pchBase <= LONG_MAX);
-        if (static_cast<charcount_t>(m_currentCharacter - m_pchBase) < this->m_cMultiUnits)
-        {
-            AssertMsg(false, "IchLimTok subtraction overflow");
-            return 0;
-        }
-
-        return static_cast< charcount_t >(m_currentCharacter - m_pchBase - this->m_cMultiUnits);
+        Assert(m_currentCharacter - m_pchBase >= 0);
+        Assert(m_currentCharacter - m_pchBase <= LONG_MAX);
+        Assert(static_cast<charcount_t>(m_currentCharacter - m_pchBase) >= this->m_cMultiUnits);
+        return static_cast<charcount_t>(m_currentCharacter - m_pchBase - this->m_cMultiUnits);
     }
 
     void SetErrorPosition(charcount_t ichMinError, charcount_t ichLimError)
@@ -557,14 +547,9 @@ class Scanner : public IScanner, public EncodingPolicy
     charcount_t IchMinLine(void) const
     {
 
-        AssertOrFailFast(m_pchMinLine - m_pchBase >= 0);
-        AssertOrFailFast(m_pchMinLine - m_pchBase <= LONG_MAX);
-        if (static_cast<charcount_t>(m_pchMinLine - m_pchBase) < m_cMinLineMultiUnits)
-        {
-            AssertMsg(false, "IchMinLine subtraction overflow");
-            return 0;
-        }
-
+        Assert(m_pchMinLine - m_pchBase >= 0);
+        Assert(m_pchMinLine - m_pchBase <= LONG_MAX);
+        Assert(static_cast<charcount_t>(m_pchMinLine - m_pchBase) >= m_cMinLineMultiUnits);
         return static_cast<charcount_t>(m_pchMinLine - m_pchBase - m_cMinLineMultiUnits);
     }
 
