JIT: remove inlining restriction for some methods that throw (#2232)

We were blocking inlines for methods that throw with more than one thing on the
evaluation stack. There was already logic for the non-inlining case to flush
the stack and preserve pending side effects. So we can simply remove the
inlining restriction.

Fixes #2156.

src/coreclr/src/jit/importer.cpp

@@ -15595,23 +15595,6 @@ void Compiler::impImportBlockCode(BasicBlock* block)
 
             case CEE_THROW:
 
-                if (compIsForInlining())
-                {
-                    // !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
-                    // TODO: Will this be too strict, given that we will inline many basic blocks?
-                    // !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
-
-                    /* Do we have just the exception on the stack ?*/
-
-                    if (verCurrentState.esStackDepth != 1)
-                    {
-                        /* if not, just don't inline the method */
-
-                        compInlineResult->NoteFatal(InlineObservation::CALLEE_THROW_WITH_INVALID_STACK);
-                        return;
-                    }
-                }
-
                 if (tiVerificationNeeded)
                 {
                     tiRetVal = impStackTop().seTypeInfo;
@@ -15622,11 +15605,14 @@ void Compiler::impImportBlockCode(BasicBlock* block)
                     }
                 }
 
-                block->bbSetRunRarely(); // any block with a throw is rare
-                /* Pop the exception object and create the 'throw' helper call */
+                // Any block with a throw is rarely executed.
+                block->bbSetRunRarely();
 
+                // Pop the exception object and create the 'throw' helper call
                 op1 = gtNewHelperCallNode(CORINFO_HELP_THROW, TYP_VOID, gtNewCallArgs(impPopStack().val));
 
+            // Fall through to clear out the eval stack.
+
             EVAL_APPEND:
                 if (verCurrentState.esStackDepth > 0)
                 {

src/coreclr/src/jit/inline.def

@@ -58,7 +58,6 @@ INLINE_OBSERVATION(NOT_PROFITABLE_INLINE,     bool,   "unprofitable inline",
 INLINE_OBSERVATION(RANDOM_REJECT,             bool,   "random reject",                 FATAL,       CALLEE)
 INLINE_OBSERVATION(STACK_CRAWL_MARK,          bool,   "uses stack crawl mark",         FATAL,       CALLEE)
 INLINE_OBSERVATION(STFLD_NEEDS_HELPER,        bool,   "stfld needs helper",            FATAL,       CALLEE)
-INLINE_OBSERVATION(THROW_WITH_INVALID_STACK,  bool,   "throw with invalid stack",      FATAL,       CALLEE)
 INLINE_OBSERVATION(TOO_MANY_ARGUMENTS,        bool,   "too many arguments",            FATAL,       CALLEE)
 INLINE_OBSERVATION(TOO_MANY_LOCALS,           bool,   "too many locals",               FATAL,       CALLEE)
 INLINE_OBSERVATION(EXPLICIT_TAIL_PREFIX,      bool,   "explicit tail prefix in callee",FATAL,       CALLEE)